LTC3351 Super Capacitor Backup Controller with HotSwap

Register Map Tables

Resigter Map Formats:
Register Map
Condensed Table
Expanded Table



Address(es) 0x09



Register Map

SUB ADDR Name Bit[15] Bit[14] Bit[13] Bit[12] Bit[11] Bit[10] Bit[9] Bit[8] Bit[7] Bit[6] Bit[5] Bit[4] Bit[3] Bit[2] Bit[1] Bit[0]
0x00ctl_reg (R/W) ctl_disable_balancer ctl_force_itst_on ctl_force_charger_off ctl_force_boost_off ctl_hotswap_disable ctl_disable_shunt ctl_cap_scale ctl_stop_cap_esr_meas ctl_gpi_buffer_en ctl_start_cap_esr_meas
0x01alarm_mask_reg (R/W) mask_alarm_esr_hi mask_alarm_cap_lo mask_alarm_cap_ov mask_alarm_cap_uv mask_alarm_iin_oc mask_alarm_ichg_uc mask_alarm_dtemp_hot mask_alarm_dtemp_cold mask_alarm_vout_ov mask_alarm_vout_uv mask_alarm_vcap_ov mask_alarm_vcap_uv mask_alarm_vin_ov mask_alarm_vin_uv mask_alarm_gpi_ov mask_alarm_gpi_uv
0x02monitor_status_mask_reg (R/W) mask_mon_cap_precharge mask_mon_shunting mask_mon_balancing mask_mon_power_returned mask_mon_power_failed mask_mon_esr_meas_active mask_mon_cap_meas_active mask_mon_disable_charger mask_mon_meas_failed mask_mon_esr_done mask_mon_cap_done mask_mon_capesr_pending mask_mon_meas_active
0x03vcapfb_dac_reg (R/W) vcapfb_dac
0x05vshunt_reg (R/W) vshunt
0x06adc_vin_ch_en_reg (R/W) adc_vin_vcap4_en adc_vin_vcap3_en adc_vin_vcap2_en adc_vin_vcap1_en adc_vin_vin_en adc_vin_vcap_en adc_vin_vout_en adc_vin_iin_en adc_vin_gpi_en adc_vin_dtemp_en adc_vin_ichg_en
0x07adc_backup_ch_en_reg (R/W) adc_backup_vcap4_en adc_backup_vcap3_en adc_backup_vcap2_en adc_backup_vcap1_en adc_backup_vin_en adc_backup_vcap_en adc_backup_vout_en adc_backup_iin_en adc_backup_gpi_en adc_backup_dtemp_en adc_backup_ichg_en
0x08adc_wait_vin_reg (R/W) adc_wait_vin
0x09adc_wait_backup_reg (R/W) adc_wait_backup
0x0Agpi_uv_lvl_reg (R/W) gpi_uv_lvl
0x0Bgpi_ov_lvl_reg (R/W) gpi_ov_lvl
0x0Cvin_uv_lvl_reg (R/W) vin_uv_lvl
0x0Dvin_ov_lvl_reg (R/W) vin_ov_lvl
0x0Evcap_uv_lvl_reg (R/W) vcap_uv_lvl
0x0Fvcap_ov_lvl_reg (R/W) vcap_ov_lvl
0x10vout_uv_lvl_reg (R/W) vout_uv_lvl
0x11vout_ov_lvl_reg (R/W) vout_ov_lvl
0x12dtemp_cold_lvl_reg (R/W) dtemp_cold_lvl
0x13dtemp_hot_lvl_reg (R/W) dtemp_hot_lvl
0x14ichg_uc_lvl_reg (R/W) ichg_uc_lvl
0x15iin_oc_lvl_reg (R/W) iin_oc_lvl
0x16cap_uv_lvl_reg (R/W) cap_uv_lvl
0x17cap_ov_lvl_reg (R/W) cap_ov_lvl
0x18cap_lo_lvl_reg (R/W) cap_lo_lvl
0x19esr_hi_lvl_reg (R/W) esr_hi_lvl
0x1Aesr_i_on_settling_reg (R/W) esr_i_on_settling
0x1Besr_i_off_settling_reg (R/W) esr_i_off_settling
0x1Cesr_i_override_reg (R/W) esr_i_override
0x1Dcap_i_on_settling_reg (R/W) cap_i_on_settling
0x1Ecap_delta_v_setting_reg (R/W) cap_delta_v_setting
0x1Fmin_boost_cap_voltage_reg (R/W) min_boost_cap_voltage
0x20min_vout_hs_disable_reg (R/W) min_vout_hs_disable
0x23alarm_reg (R/W) alarm_esr_hi alarm_cap_lo alarm_cap_ov alarm_cap_uv alarm_iin_oc alarm_ichg_uc alarm_dtemp_hot alarm_dtemp_cold alarm_vout_ov alarm_vout_uv alarm_vcap_ov alarm_vcap_uv alarm_vin_ov alarm_vin_uv alarm_gpi_ov alarm_gpi_uv
0x24monitor_status_reg (R) mon_reset mon_cap_precharge mon_shunting mon_balancing mon_power_returned mon_power_failed mon_esr_meas_active mon_cap_meas_active mon_disable_charger mon_boost_shutdown mon_meas_failed mon_esr_done mon_cap_done mon_capesr_pending mon_capesr_scheduled mon_meas_active
0x25meas_gpi_reg (R) meas_gpi
0x26meas_vin_reg (R) meas_vin
0x27meas_vcap_reg (R) meas_vcap
0x28meas_vout_reg (R) meas_vout
0x29meas_dtemp_reg (R) meas_dtemp
0x2Ameas_ichg_reg (R) meas_ichg
0x2Bmeas_iin_reg (R) meas_iin
0x2Clo_vcap_reg (R) lo_vcap
0x2Dhi_vcap_reg (R) hi_vcap
0x2Emeas_cap_reg (R) meas_cap
0x2Fmeas_esr_reg (R) meas_esr
0x30meas_vcap1_reg (R) meas_vcap1
0x31meas_vcap2_reg (R) meas_vcap2
0x32meas_vcap3_reg (R) meas_vcap3
0x33meas_vcap4_reg (R) meas_vcap4
0x34cap_m0_vc1_reg (R) cap_m0_vc1
0x35cap_m0_vc2_reg (R) cap_m0_vc2
0x36cap_m0_vc3_reg (R) cap_m0_vc3
0x37cap_m0_vc4_reg (R) cap_m0_vc4
0x38esr_m0_vc1_reg (R) esr_m0_vc1
0x39esr_m0_vc2_reg (R) esr_m0_vc2
0x3Aesr_m0_vc3_reg (R) esr_m0_vc3
0x3Besr_m0_vc4_reg (R) esr_m0_vc4
0x3Cesr_m1_vc1_reg (R) esr_m1_vc1
0x3Desr_m1_vc2_reg (R) esr_m1_vc2
0x3Eesr_m1_vc3_reg (R) esr_m1_vc3
0x3Fesr_m1_vc4_reg (R) esr_m1_vc4
0x40esr_m1_i_reg (R) esr_m1_i
0x41esr_m2_vc1_reg (R) esr_m2_vc1
0x42esr_m2_vc2_reg (R) esr_m2_vc2
0x43esr_m2_vc3_reg (R) esr_m2_vc3
0x44esr_m2_vc4_reg (R) esr_m2_vc4
0x45esr_m2_i_reg (R) esr_m2_i
0x46esr_m3_vc1_reg (R) esr_m3_vc1
0x47esr_m3_vc2_reg (R) esr_m3_vc2
0x48esr_m3_vc3_reg (R) esr_m3_vc3
0x49esr_m3_vc4_reg (R) esr_m3_vc4
0x4Aesr_m3_i_reg (R) esr_m3_i
0x50rev_reg (R) rev_code
0x54next_ichrg_control_test_current (R) next_esr_i
0xEDnum_caps_reg (R) num_caps
0xEEsys_status (R) vingd chrg_ci buck_en boost_en cappg chrg_input_ilim chrg_uvlo chrg_cv stepup_mode stepdown_mode

Condensed Table

SYMBOL
SUB
ADDR
R/W
BITS
DEFAULT
DESCRIPTION
ctl_reg
0x00
R/W
10:0
0
Control Register: Several independent control bits are grouped into this register.
   ctl_start_cap_esr_meas
0
0
Begin a capacitance and ESR measurement when possible; this bit clears itself once a measurement cycle begins or becomes pending.
   ctl_gpi_buffer_en
1
0
A one in this bit location enables the input buffer on the GPI pin. With a zero in this location the GPI pin is measured without the buffer.
   ctl_stop_cap_esr_meas
2
0
Stops an active capacitance/ESR measurement; this bit clears itself once a measurement cycle has been stopped.
   ctl_cap_scale
3
0
Increases capacitor measurement resolution 100 times, this is used when measuring smaller capacitors.
   ctl_disable_shunt
4
0
Disables the shunt feature.
   ctl_hotswap_disable
5
0
Disables the HotSwap controller. The gate of the hotswap FET is forced low, disconnecting VIN and VOUT and forcing the switcher into backup mode. This can be used to simulate a power failure for testing.
   ctl_force_boost_off
6
0
This bit disables the boost.
   ctl_force_charger_off
7
0
This bit disables the charger.
   ctl_force_itst_on
8
0
This bit forces the ITST current on. This can be used to discharge the capacitor stack or manually measure capacitance. Note that this only enables the test current, it does not disable the charger. Set ctl_force_charger_off to disable the charger.
   ctl_disable_balancer
10
0
Disables the balancer.
alarm_mask_reg
0x01
R/W
15:0
0
Mask Alarms Register: Writing a one to any bit in this register enables a rising edge of its respective bit in alarm_reg to trigger an SMBALERT.
   mask_alarm_gpi_uv
0
0
GPI Under Voltage alarm mask
   mask_alarm_gpi_ov
1
0
GPI Over Voltage alarm mask
   mask_alarm_vin_uv
2
0
VIN Under Voltage alarm mask
   mask_alarm_vin_ov
3
0
VIN Over Voltage alarm mask
   mask_alarm_vcap_uv
4
0
VCAP Under Voltage alarm mask
   mask_alarm_vcap_ov
5
0
VCAP Over Voltage alarm mask
   mask_alarm_vout_uv
6
0
VOUT Under Voltage alarm mask
   mask_alarm_vout_ov
7
0
VOUT Over Voltage alarm mask
   mask_alarm_dtemp_cold
8
0
Die temperature cold alarm mask
   mask_alarm_dtemp_hot
9
0
Die temperature hot alarm mask
   mask_alarm_ichg_uc
10
0
Charge undercurrent alarm mask
   mask_alarm_iin_oc
11
0
Input overcurrent alarm mask
   mask_alarm_cap_uv
12
0
Capacitor Under Voltage alarm mask
   mask_alarm_cap_ov
13
0
Capacitor Over Voltage alarm mask
   mask_alarm_cap_lo
14
0
Capacitance low alarm mask
   mask_alarm_esr_hi
15
0
ESR high alarm mask
monitor_status_mask_reg
0x02
R/W
14:0
0
Mask Monitor Status Register: Writing a one to any bit in this register enables a rising edge of its respective bit in monitor_status_reg to trigger an SMBALERT.
   mask_mon_meas_active
0
0
Set the SMBALERT when there is a rising edge on mon_meas_active
   mask_mon_capesr_pending
2
0
Set the SMBALERT when there is a rising edge on mon_capesr_pending
   mask_mon_cap_done
3
0
Set the SMBALERT when there is a rising edge on mon_cap_done
   mask_mon_esr_done
4
0
Set the SMBALERT when there is a rising edge on mon_esr_done
   mask_mon_meas_failed
5
0
Set the SMBALERT when there is a rising edge on mon_meas_failed
   mask_mon_disable_charger
7
0
Set the SMBALERT when there is a rising edge on mon_disable_charger
   mask_mon_cap_meas_active
8
0
Set the SMBALERT when there is a rising edge on mon_cap_meas_active
   mask_mon_esr_meas_active
9
0
Set the SMBALERT when there is a rising edge on mon_esr_meas_active
   mask_mon_power_failed
10
0
Set the SMBALERT when there is a rising edge on mon_power_failed
   mask_mon_power_returned
11
0
Set the SMBALERT when there is a rising edge on mon_power_returned
   mask_mon_balancing
12
0
Set the SMBALERT when there is a rising edge on mon_balancing
   mask_mon_shunting
13
0
Set the SMBALERT when there is a rising edge on mon_shunting
   mask_mon_cap_precharge
14
0
Set the SMBALERT when there is a rising edge on mon_cap_precharge
vcapfb_dac
0x03
R/W
3:0
10
VCAP Regulation Reference: This register is used to program the capacitor voltage feedback loop's reference voltage. Only bits 3:0 are active. VCAPFB_DAC = 37.5mV * vcapfb_dac + 637.5mV
vshunt
0x05
R/W
15:0
14744
Shunt Voltage Register: This register programs the shunt voltage for each capacitor in the stack. When set below 3.6V, the charger will limit current and the active shunts will shunt current to prevent this voltage from being exceeded. As a capacitor voltage nears this level, the charge current will be reduced. Current will be shunted when the capacitor voltage is within 25mV of vshunt. Vshunt should be programmed at least 50mV higher than the intended final balanced individual capacitor voltage. When programmed above 3.6V no current will be shunted, however the charge current will be reduced as described. 182.8µV per LSB.
adc_vin_ch_en_reg
0x06
R/W
11:1
3842
   adc_vin_ichg_en
1
1
Enables ADC measurement of charge current while in charging mode.
   adc_vin_dtemp_en
2
0
Enables ADC measurement of die temperature while in charging mode.
   adc_vin_gpi_en
3
0
Enables ADC measurement of GPI (general purpose input) while in charging mode.
   adc_vin_iin_en
4
0
Enables ADC measurement of input current while in charging mode.
   adc_vin_vout_en
5
0
Enables ADC measurement of vout while in charging mode.
   adc_vin_vcap_en
6
0
Enables ADC measurement of vcap while in charging mode.
   adc_vin_vin_en
7
0
Enables ADC measurement of vin while in charging mode.
   adc_vin_vcap1_en
8
1
Enables ADC measurement of vcap1 while in charging mode. This bit must be set for capacitance and ESR measurement.
   adc_vin_vcap2_en
9
1
Enables ADC measurement of vcap2 while in charging mode. This bit must be set for capacitance and ESR measurement if there are two or more capacitors in the stack.
   adc_vin_vcap3_en
10
1
Enables ADC measurement of vcap3 while in charging mode. This bit must be set for capacitance and ESR measurement if there are three or more capacitors in the stack
   adc_vin_vcap4_en
11
1
Enables ADC measurement of vcap4 while in charging mode. This bit must be set for capacitance and ESR measurement if there are four capacitors in the stack
adc_backup_ch_en_reg
0x07
R/W
11:1
0
   adc_backup_ichg_en
1
0
Enables ADC measurement of charge current while in backup mode.
   adc_backup_dtemp_en
2
0
Enables ADC measurement of die temperature while in backup mode.
   adc_backup_gpi_en
3
0
Enables ADC measurement of GPI (general purpose input) while in backup mode.
   adc_backup_iin_en
4
0
Enables ADC measurement of input current while in backup mode.
   adc_backup_vout_en
5
0
Enables ADC measurement of vout while in backup mode.
   adc_backup_vcap_en
6
0
Enables ADC measurement of vcap while in backup mode.
   adc_backup_vin_en
7
0
Enables ADC measurement of vin while in backup mode.
   adc_backup_vcap1_en
8
0
Enables ADC measurement of vcap1 while in backup mode.
   adc_backup_vcap2_en
9
0
Enables ADC measurement of vcap2 while in backup mode.
   adc_backup_vcap3_en
10
0
Enables ADC measurement of vcap3 while in backup mode.
   adc_backup_vcap4_en
11
0
Enables ADC measurement of vcap4 while in backup mode.
adc_wait_vin
0x08
R/W
15:0
100
Sets the wait time between ADC measurement groups while in charging mode. The LSB of this register has a weight of 400uS. The ADC measures all enabled channels then waits this time before measuring all channels again. The ADC data is used for balancing and shunting, increasing this time reduces the shunt and balancer update rate and is not typically recommended if shunting or balancing is enabled. If shunting or measuring capacitance/ESR this time may be ignored by the ADC. 400uS per LSB
adc_wait_backup
0x09
R/W
15:0
100
Sets the wait time between ADC measurement groups while in backup mode. The LSB of this register has a weight of 400uS. The ADC measures all enabled channels then waits this time before measuring all channels again. 400uS per LSB
gpi_uv_lvl
0x0A
R/W
15:0
0
General Purpose Input Under Voltage Level: This is an alarm threshold for the GPI pin. If enabled, the GPI pin voltage falling below this level will trigger an alarm and an SMBALERT. 182.8µV per LSB
gpi_ov_lvl
0x0B
R/W
15:0
0
General Purpose Input Over Voltage Level: This is an alarm threshold for the GPI pin. If enabled, the GPI pin voltage rising above this level will trigger an alarm and an SMBALERT. 182.8µV per LSB
vin_uv_lvl
0x0C
R/W
15:0
0
VIN Under Voltage Level: This is an alarm threshold for the input voltage. If enabled, the input pin voltage falling below this level will trigger an alarm and an SMBALERT. 2.19mV per LSB
vin_ov_lvl
0x0D
R/W
15:0
0
VIN Over Voltage Level: This is an alarm threshold for the input voltage. If enabled, the input pin voltage rising above this level will trigger an alarm and an SMBALERT. 2.19mV per LSB
vcap_uv_lvl
0x0E
R/W
15:0
0
VCAP Under Voltage Level: This is an alarm threshold for the capacitor stack voltage. If enabled, the VCAP pin voltage falling below this level will trigger an alarm and an SMBALERT. 1.46mV per LSB
vcap_ov_lvl
0x0F
R/W
15:0
0
VCAP Over Voltage Level: This is an alarm threshold for the capacitor stack voltage. If enabled, the VCAP pin voltage rising above this level will trigger an alarm and an SMBALERT. 1.46mV per LSB
vout_uv_lvl
0x10
R/W
15:0
0
VOUT Under Voltage Level: This is an alarm threshold for the output voltage. If enabled, the VOUT pin voltage falling below this level will trigger an alarm and an SMBALERT. 2.19mV per LSB
vout_ov_lvl
0x11
R/W
15:0
0
VOUT Over Voltage Level: This is an alarm threshold for the output voltage. If enabled, the VOUT pin voltage rising above this level will trigger an alarm and an SMBALERT. 2.19mV per LSB
dtemp_cold_lvl
0x12
R/W
15:0
0
Die Temperature Cold Level: This is an alarm threshold for the die temperature. If enabled, the die temperature falling below this level will trigger an alarm and an SMBALERT. Temperature = 0.0295C per LSB - 274C
dtemp_hot_lvl
0x13
R/W
15:0
0
Die Temperature Hot Level: This is an alarm threshold for the die temperature. If enabled, the die temperature rising above this level will trigger an alarm and an SMBALERT. Temperature = 0.0295C per LSB - 274C
ichg_uc_lvl
0x14
R/W
15:0
0
Charge Undercurrent Level: This is an alarm threshold for the charge current. If enabled, the charge current falling below this level will trigger an alarm and an SMBALERT. 1.955µV/Rsnsc per LSB
iin_oc_lvl
0x15
R/W
15:0
0
Input Overcurrent Level: This is an alarm threshold for the input current. If enabled, the input current rising above this level will trigger an alarm and an SMBALERT. 1.955µV/Rsnsi per LSB
cap_uv_lvl
0x16
R/W
15:0
0
Capacitor Under Voltage Level: This is an alarm threshold for each individual capacitor voltage in the stack. If enabled, any capacitor voltage falling below this level will trigger an alarm and an SMBALERT. 182.8µV per LSB.
cap_ov_lvl
0x17
R/W
15:0
0
Capacitor Over Voltage Level: This is an alarm threshold for each individual capacitor in the stack. If enabled, any capacitor voltage rising above this level will trigger an alarm and an SMBALERT. 182.8µV per LSB
cap_lo_lvl
0x18
R/W
15:0
0
Capacitance Low Level: This is an alarm threshold for the measured stack capacitance. If the measured stack capacitance is less than this level it will trigger an alarm and an SMBALERT, if enabled. When ctl_cap_scale is set to 1, capacitance is 3.36µF * RT/RTST per LSB. When ctl_cap_scale is set to 0 it is 336µF * RT/RTST per LSB.
esr_hi_lvl
0x19
R/W
15:0
0
ESR High Level: This is an alarm threshold for the measured stack ESR. If enabled, a measurement of stack ESR exceeding this level will trigger an alarm and an SMBALERT. Rsnsc/64 per LSB.
esr_i_on_settling
0x1A
R/W
15:0
2
Time to allow the charging current to settle before measuring the charge voltage and current for ESR. Each LSB is 1024 switcher periods.
esr_i_off_settling
0x1B
R/W
15:0
8
Time to wait after turning the charge current off before measuring the charge voltage and current for ESR. Each LSB is 1024 switcher periods.
esr_i_override
0x1C
R/W
15:0
0
This value overrides the LTC3351's adaptive test current selection for the ESR test. If this register is non-zero, the lower 8 bits will be used as an 8 bit DAC value to set the charge current during the ESR test. Typically this register will not need to be set. ITEST = 32mV * (esr_i_override[7:0] + 1) / 256 / Rsnsc
cap_i_on_settling
0x1D
R/W
15:0
8
Time to wait after turning the test current on before measuring the first voltage of the capacitance measurement. Each LSB is 1024 switcher periods.
cap_delta_v_setting
0x1E
R/W
15:0
550
The target delta V for the capacitance test. The scale is 182.8µV per LSB. The default is approximately 100mV.
min_boost_cap_voltage
0x1F
R/W
15:0
0
If this register is non-zero, it sets the minimum capacitor voltage the boost will operate at. If any capacitor voltage falls below this value in boost mode the boost will be forced off, the boost will not turn back on even if the capacitor voltage rises above this voltage. Only after input power returns will the boost be re-enabled. This prevents the boost from cycling on and off many times once the capacitors' voltage has discharged to the point it can no longer support the system load through the boost. To use this feature vcap[1:num_caps+1] measurements must be enabled in backup mode, see adc_backup_ch_en_reg. Also the capacitor voltages are only measured as often as set by adc_wait_backup.
min_vout_hs_disable
0x20
R/W
15:0
0
If this register is non-zero, it sets the minimum voltage VOUT is allowed to reach while the HotSwap is disabled. If the voltage falls below this level the ctl_hotswap_disable bit will be cleared, re-enabling the HotSwap controller. To use this feature the VOUT measurement must be enabled in boost mode, see adc_backup_ch_en_reg. Also the VOUT voltage is only measured as often as set by adc_wait_backup.
alarm_reg
0x23
R/W
15:0
0
Alarms Register: A one in any bit in the register indicates its respective alarm has triggered. All bits are active high. Alarms are cleared by clearing (writing 0) the appropriate bit in this register. Setting (writing 1) bits has no effect. For example to clear the alarm_gpi_uv alarm, write 0xFFFD.
   alarm_gpi_uv
0
0
GPI Under Voltage alarm
   alarm_gpi_ov
1
0
GPI Over Voltage alarm
   alarm_vin_uv
2
0
VIN Under Voltage alarm
   alarm_vin_ov
3
0
VIN Over Voltage alarm
   alarm_vcap_uv
4
0
VCAP Under Voltage alarm
   alarm_vcap_ov
5
0
VCAP Over Voltage alarm
   alarm_vout_uv
6
0
VOUT Under Voltage alarm
   alarm_vout_ov
7
0
VOUT Over Voltage alarm
   alarm_dtemp_cold
8
0
Die temperature cold alarm
   alarm_dtemp_hot
9
0
Die temperature hot alarm
   alarm_ichg_uc
10
0
Charge undercurrent alarm
   alarm_iin_oc
11
0
Input overcurrent alarm
   alarm_cap_uv
12
0
Capacitor Under Voltage alarm
   alarm_cap_ov
13
0
Capacitor Over Voltage alarm
   alarm_cap_lo
14
0
Capacitance low alarm
   alarm_esr_hi
15
0
ESR high alarm
monitor_status_reg
0x24
R
15:0
N/A
Monitor Status: This register provides real time status information about the state of the monitoring system. Each bit is active high.
   mon_meas_active
0
N/A
Capacitance/ESR measurement is active. This bit becomes one at the begining of a capacitance/ESR measurement and remains 1 after the measurement has completed until the capacitors have been discharged back to their regulation voltage.
   mon_capesr_scheduled
1
N/A
Indicates that the LTC3351 is waiting programmed time to begin a capacitance/ESR measurement
   mon_capesr_pending
2
N/A
Indicates that the LTC3351 is waiting for satisfactory conditions to begin a capacitance/ESR measurement
   mon_cap_done
3
N/A
Indicates that the capacitance measurement has completed
   mon_esr_done
4
N/A
Indicates that the ESR Measurement has completed
   mon_meas_failed
5
N/A
Indicates the last attempted capacitance and ESR measurement was unable to complete
   mon_boost_shutdown
6
N/A
This bit is set in boost mode when any capacitor falls below min_boost_cap_voltage_reg. It is cleared when power returns.
   mon_disable_charger
7
N/A
Indicates the capacitance and ESR measurement system has temporarily disabled the charger.
   mon_cap_meas_active
8
N/A
Indicates the capacitance and ESR measurement system is measuring capacitance.
   mon_esr_meas_active
9
N/A
Indicates the capacitance and ESR measurement system is measuring ESR.
   mon_power_failed
10
N/A
This bit is set when VIN is outside the UV/OV range or the HotSwap controller is disabled by setting the ctl_hotswap_disable. It is cleared only when mon_power_returned is set.
   mon_power_returned
11
N/A
This bit is set when the output is powered by the input and the charger is able to charge. It is cleared only when mon_power_failed is set.
   mon_balancing
12
N/A
Indicates the LTC3351 is balancing the capacitor voltage.
   mon_shunting
13
N/A
Indicates a capacitor voltage is approaching vshunt and a shunt is turned on.
   mon_cap_precharge
14
N/A
Indicates the capacitor stack is being precharged for a capacitance measurement.
   mon_reset
15
N/A
This bit is set during a power on reset. It is cleared on any I2C/SMBus write. It can be used to determine if the chip has reset during a power loss followed by a power return.
meas_gpi
0x25
R
15:0
N/A
Measurement of GPI pin voltage. 182.8µV per LSB
meas_vin
0x26
R
15:0
N/A
Measured Input Voltage. 2.19mV per LSB
meas_vcap
0x27
R
15:0
N/A
Measured Capacitor Stack Voltage. 1.46mV per LSB.
meas_vout
0x28
R
15:0
N/A
Measured Output Voltage. 2.19mV per LSB.
meas_dtemp
0x29
R
15:0
N/A
Measured die temperature. Temperature = 0.0295°C per LSB - 274°C.
meas_ichg
0x2A
R
15:0
N/A
Measured Charge Current. 1.955µV/Rsnsc per LSB
meas_iin
0x2B
R
15:0
N/A
Measured Input Current. 1.955µV/Rsnsi per LSB
lo_vcap
0x2C
R
15:0
N/A
The lowest measured capacitor voltage from the last measurement set.
hi_vcap
0x2D
R
15:0
N/A
The highest measured capacitor voltage from the last measurement set.
meas_cap
0x2E
R
15:0
N/A
Measured capacitor stack capacitance value. When ctl_cap_scale is set to 1, capacitance is 3.36µF * RT/RTST per LSB. When ctl_cap_scale is set to 0 it is 336µF * RT/RTST per LSB.
meas_esr
0x2F
R
15:0
N/A
Measured capacitor stack equivalent series resistance (ESR) value. Rsnsc/64 per LSB
meas_vcap1
0x30
R
15:0
N/A
Measured voltage between the CAP1 and CAPRTN pins. 182.8µV per LSB
meas_vcap2
0x31
R
15:0
N/A
Measured voltage between the CAP2 and CAP1 pins. 182.8µV per LSB
meas_vcap3
0x32
R
15:0
N/A
Measured voltage between the CAP3 and CAP2 pins. 182.8µV per LSB
meas_vcap4
0x33
R
15:0
N/A
Measured voltage between the CAP4 and CAP3 pins. 182.8µV per LSB. When the ITST current is on, either due to ctl_force_itst_on or during a capacitance measurement, this voltage measurement will temporarily be low due to the ITST current flowing in the shunt resistor.
cap_m0_vc1
0x34
R
15:0
N/A
The voltage change on cap1 due to the capacitance measurement. The relative voltage change on each capacitor during the capacitance measurement and the total capacitance can be used to calculate the capacitance of each individual capacitor.
cap_m0_vc2
0x35
R
15:0
N/A
The voltage change on cap2 due to the capacitance measurement. The relative voltage change on each capacitor during the capacitance measurement and the total capacitance can be used to calculate the capacitance of each individual capacitor.
cap_m0_vc3
0x36
R
15:0
N/A
The voltage change on cap3 due to the capacitance measurement. The relative voltage change on each capacitor during the capacitance measurement and the total capacitance can be used to calculate the capacitance of each individual capacitor.
cap_m0_vc4
0x37
R
15:0
N/A
The voltage change on cap4 due to the capacitance measurement. The relative voltage change on each capacitor during the capacitance measurement and the total capacitance can be used to calculate the capacitance of each individual capacitor.
esr_m0_vc1
0x38
R
15:0
N/A
A measurement of VCAP1 just before turning current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m0_vc2
0x39
R
15:0
N/A
A measurement of VCAP2 just before turning current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m0_vc3
0x3A
R
15:0
N/A
A measurement of VCAP3 just before turning current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m0_vc4
0x3B
R
15:0
N/A
A measurement of VCAP4 just before turning current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m1_vc1
0x3C
R
15:0
N/A
The first VCAP1 voltage measurement with charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m1_vc2
0x3D
R
15:0
N/A
The first VCAP2 voltage measurement with charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m1_vc3
0x3E
R
15:0
N/A
The first VCAP3 voltage measurement with charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m1_vc4
0x3F
R
15:0
N/A
The first VCAP4 voltage measurement with charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m1_i
0x40
R
15:0
N/A
The first charge current measurement with charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m2_vc1
0x41
R
15:0
N/A
The second VCAP1 voltage measurement with the charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m2_vc2
0x42
R
15:0
N/A
The second VCAP2 voltage measurement with the charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m2_vc3
0x43
R
15:0
N/A
The second VCAP3 voltage measurement with the charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m2_vc4
0x44
R
15:0
N/A
The second VCAP4 voltage measurement with the charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m2_i
0x45
R
15:0
N/A
The second charge current measurement with charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m3_vc1
0x46
R
15:0
N/A
The VCAP1 voltage measurement with charge current off for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m3_vc2
0x47
R
15:0
N/A
The VCAP2 voltage measurement with charge current off for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m3_vc3
0x48
R
15:0
N/A
The VCAP3 voltage measurement with charge current off for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m3_vc4
0x49
R
15:0
N/A
The VCAP4 voltage measurement with charge current off for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
esr_m3_i
0x4A
R
15:0
N/A
The charge current measurement with charge current off for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
rev_code
0x50
R
15:0
N/A
The LTC3351 revision code.
next_esr_i
0x54
R
7:0
N/A
The 8 bit DAC setting for the charge current that the LTC3351 has calculated for the next ESR measurement based on the previous ESR measurement. The first ESR measurement will use a setting of 32. If esr_i_override is non-zero, this register will be calculated but esr_i_override will be used instead. If non-zero ITEST = 32mV * (next_esr_i[7:0] + 1) / 256 / Rsnsc
num_caps
0xED
R
1:0
N/A
Number of Capacitors. This register shows the state of the CAP_SLCT1, CAP_SLCT0 pins. The value read in this register is the number of capacitors programmed minus one.
sys_status
0xEE
R
11:0
N/A
System Status Register: This register provides real time status information about the instantaneous state of the system. Each bit is active high.
   stepdown_mode
0
N/A
The synchronous controller is in step-down mode (charging)
   stepup_mode
1
N/A
The synchronous controller is in step-up mode (backup)
   chrg_cv
2
N/A
The charger is in constant voltage mode
   chrg_uvlo
3
N/A
The charger is in under-voltage lockout or has been disabled by ctl_force_charger_off.
   chrg_input_ilim
4
N/A
The charger is in input current limit
   cappg
5
N/A
The capacitor voltage is above power good threshold
   boost_en
7
N/A
Indicates the boost is enabled
   buck_en
8
N/A
Indicates the charger is enabled
   chrg_ci
9
N/A
Indicates the charger is in constant current mode
   vingd
11
N/A
Indicates the input voltage is inside the UV/OV range.

Expanded Table

 
ctl_reg   Address: 0x00 (R/W)
Control Register: Several independent control bits are grouped into this register.
Bit 0: ctl_start_cap_esr_meas (Default = 0)
Begin a capacitance and ESR measurement when possible; this bit clears itself once a measurement cycle begins or becomes pending.
1: start_measurement
Bit 1: ctl_gpi_buffer_en (Default = 0)
A one in this bit location enables the input buffer on the GPI pin. With a zero in this location the GPI pin is measured without the buffer.
Bit 2: ctl_stop_cap_esr_meas (Default = 0)
Stops an active capacitance/ESR measurement; this bit clears itself once a measurement cycle has been stopped.
1: stop_measurement
Bit 3: ctl_cap_scale (Default = 0)
Increases capacitor measurement resolution 100 times, this is used when measuring smaller capacitors.
0: large_cap
1: small_cap
Bit 4: ctl_disable_shunt (Default = 0)
Disables the shunt feature.
Bit 5: ctl_hotswap_disable (Default = 0)
Disables the HotSwap controller. The gate of the hotswap FET is forced low, disconnecting VIN and VOUT and forcing the switcher into backup mode. This can be used to simulate a power failure for testing.
Bit 6: ctl_force_boost_off (Default = 0)
This bit disables the boost.
Bit 7: ctl_force_charger_off (Default = 0)
This bit disables the charger.
Bit 8: ctl_force_itst_on (Default = 0)
This bit forces the ITST current on. This can be used to discharge the capacitor stack or manually measure capacitance. Note that this only enables the test current, it does not disable the charger. Set ctl_force_charger_off to disable the charger.
Bit 10: ctl_disable_balancer (Default = 0)
Disables the balancer.
 
alarm_mask_reg   Address: 0x01 (R/W)
Mask Alarms Register: Writing a one to any bit in this register enables a rising edge of its respective bit in alarm_reg to trigger an SMBALERT.
Bit 0: mask_alarm_gpi_uv (Default = 0)
GPI Under Voltage alarm mask
Bit 1: mask_alarm_gpi_ov (Default = 0)
GPI Over Voltage alarm mask
Bit 2: mask_alarm_vin_uv (Default = 0)
VIN Under Voltage alarm mask
Bit 3: mask_alarm_vin_ov (Default = 0)
VIN Over Voltage alarm mask
Bit 4: mask_alarm_vcap_uv (Default = 0)
VCAP Under Voltage alarm mask
Bit 5: mask_alarm_vcap_ov (Default = 0)
VCAP Over Voltage alarm mask
Bit 6: mask_alarm_vout_uv (Default = 0)
VOUT Under Voltage alarm mask
Bit 7: mask_alarm_vout_ov (Default = 0)
VOUT Over Voltage alarm mask
Bit 8: mask_alarm_dtemp_cold (Default = 0)
Die temperature cold alarm mask
Bit 9: mask_alarm_dtemp_hot (Default = 0)
Die temperature hot alarm mask
Bit 10: mask_alarm_ichg_uc (Default = 0)
Charge undercurrent alarm mask
Bit 11: mask_alarm_iin_oc (Default = 0)
Input overcurrent alarm mask
Bit 12: mask_alarm_cap_uv (Default = 0)
Capacitor Under Voltage alarm mask
Bit 13: mask_alarm_cap_ov (Default = 0)
Capacitor Over Voltage alarm mask
Bit 14: mask_alarm_cap_lo (Default = 0)
Capacitance low alarm mask
Bit 15: mask_alarm_esr_hi (Default = 0)
ESR high alarm mask
 
monitor_status_mask_reg   Address: 0x02 (R/W)
Mask Monitor Status Register: Writing a one to any bit in this register enables a rising edge of its respective bit in monitor_status_reg to trigger an SMBALERT.
Bit 0: mask_mon_meas_active (Default = 0)
Set the SMBALERT when there is a rising edge on mon_meas_active
Bit 2: mask_mon_capesr_pending (Default = 0)
Set the SMBALERT when there is a rising edge on mon_capesr_pending
Bit 3: mask_mon_cap_done (Default = 0)
Set the SMBALERT when there is a rising edge on mon_cap_done
Bit 4: mask_mon_esr_done (Default = 0)
Set the SMBALERT when there is a rising edge on mon_esr_done
Bit 5: mask_mon_meas_failed (Default = 0)
Set the SMBALERT when there is a rising edge on mon_meas_failed
Bit 7: mask_mon_disable_charger (Default = 0)
Set the SMBALERT when there is a rising edge on mon_disable_charger
Bit 8: mask_mon_cap_meas_active (Default = 0)
Set the SMBALERT when there is a rising edge on mon_cap_meas_active
Bit 9: mask_mon_esr_meas_active (Default = 0)
Set the SMBALERT when there is a rising edge on mon_esr_meas_active
Bit 10: mask_mon_power_failed (Default = 0)
Set the SMBALERT when there is a rising edge on mon_power_failed
Bit 11: mask_mon_power_returned (Default = 0)
Set the SMBALERT when there is a rising edge on mon_power_returned
Bit 12: mask_mon_balancing (Default = 0)
Set the SMBALERT when there is a rising edge on mon_balancing
Bit 13: mask_mon_shunting (Default = 0)
Set the SMBALERT when there is a rising edge on mon_shunting
Bit 14: mask_mon_cap_precharge (Default = 0)
Set the SMBALERT when there is a rising edge on mon_cap_precharge
 
vcapfb_dac_reg   Address: 0x03 (R/W)
Bits [3:0]: vcapfb_dac (Default = 10)
VCAP Regulation Reference: This register is used to program the capacitor voltage feedback loop's reference voltage. Only bits 3:0 are active. VCAPFB_DAC = 37.5mV * vcapfb_dac + 637.5mV
 
vshunt_reg   Address: 0x05 (R/W)
Bits [15:0]: vshunt (Default = 14744)
Shunt Voltage Register: This register programs the shunt voltage for each capacitor in the stack. When set below 3.6V, the charger will limit current and the active shunts will shunt current to prevent this voltage from being exceeded. As a capacitor voltage nears this level, the charge current will be reduced. Current will be shunted when the capacitor voltage is within 25mV of vshunt. Vshunt should be programmed at least 50mV higher than the intended final balanced individual capacitor voltage. When programmed above 3.6V no current will be shunted, however the charge current will be reduced as described. 182.8µV per LSB.
 
adc_vin_ch_en_reg   Address: 0x06 (R/W)
Bit 1: adc_vin_ichg_en (Default = 1)
Enables ADC measurement of charge current while in charging mode.
Bit 2: adc_vin_dtemp_en (Default = 0)
Enables ADC measurement of die temperature while in charging mode.
Bit 3: adc_vin_gpi_en (Default = 0)
Enables ADC measurement of GPI (general purpose input) while in charging mode.
Bit 4: adc_vin_iin_en (Default = 0)
Enables ADC measurement of input current while in charging mode.
Bit 5: adc_vin_vout_en (Default = 0)
Enables ADC measurement of vout while in charging mode.
Bit 6: adc_vin_vcap_en (Default = 0)
Enables ADC measurement of vcap while in charging mode.
Bit 7: adc_vin_vin_en (Default = 0)
Enables ADC measurement of vin while in charging mode.
Bit 8: adc_vin_vcap1_en (Default = 1)
Enables ADC measurement of vcap1 while in charging mode. This bit must be set for capacitance and ESR measurement.
Bit 9: adc_vin_vcap2_en (Default = 1)
Enables ADC measurement of vcap2 while in charging mode. This bit must be set for capacitance and ESR measurement if there are two or more capacitors in the stack.
Bit 10: adc_vin_vcap3_en (Default = 1)
Enables ADC measurement of vcap3 while in charging mode. This bit must be set for capacitance and ESR measurement if there are three or more capacitors in the stack
Bit 11: adc_vin_vcap4_en (Default = 1)
Enables ADC measurement of vcap4 while in charging mode. This bit must be set for capacitance and ESR measurement if there are four capacitors in the stack
 
adc_backup_ch_en_reg   Address: 0x07 (R/W)
Bit 1: adc_backup_ichg_en (Default = 0)
Enables ADC measurement of charge current while in backup mode.
Bit 2: adc_backup_dtemp_en (Default = 0)
Enables ADC measurement of die temperature while in backup mode.
Bit 3: adc_backup_gpi_en (Default = 0)
Enables ADC measurement of GPI (general purpose input) while in backup mode.
Bit 4: adc_backup_iin_en (Default = 0)
Enables ADC measurement of input current while in backup mode.
Bit 5: adc_backup_vout_en (Default = 0)
Enables ADC measurement of vout while in backup mode.
Bit 6: adc_backup_vcap_en (Default = 0)
Enables ADC measurement of vcap while in backup mode.
Bit 7: adc_backup_vin_en (Default = 0)
Enables ADC measurement of vin while in backup mode.
Bit 8: adc_backup_vcap1_en (Default = 0)
Enables ADC measurement of vcap1 while in backup mode.
Bit 9: adc_backup_vcap2_en (Default = 0)
Enables ADC measurement of vcap2 while in backup mode.
Bit 10: adc_backup_vcap3_en (Default = 0)
Enables ADC measurement of vcap3 while in backup mode.
Bit 11: adc_backup_vcap4_en (Default = 0)
Enables ADC measurement of vcap4 while in backup mode.
 
adc_wait_vin_reg   Address: 0x08 (R/W)
Bits [15:0]: adc_wait_vin (Default = 100)
Sets the wait time between ADC measurement groups while in charging mode. The LSB of this register has a weight of 400uS. The ADC measures all enabled channels then waits this time before measuring all channels again. The ADC data is used for balancing and shunting, increasing this time reduces the shunt and balancer update rate and is not typically recommended if shunting or balancing is enabled. If shunting or measuring capacitance/ESR this time may be ignored by the ADC. 400uS per LSB
 
adc_wait_backup_reg   Address: 0x09 (R/W)
Bits [15:0]: adc_wait_backup (Default = 100)
Sets the wait time between ADC measurement groups while in backup mode. The LSB of this register has a weight of 400uS. The ADC measures all enabled channels then waits this time before measuring all channels again. 400uS per LSB
 
gpi_uv_lvl_reg   Address: 0x0A (R/W)
Bits [15:0]: gpi_uv_lvl (Default = 0)
General Purpose Input Under Voltage Level: This is an alarm threshold for the GPI pin. If enabled, the GPI pin voltage falling below this level will trigger an alarm and an SMBALERT. 182.8µV per LSB
 
gpi_ov_lvl_reg   Address: 0x0B (R/W)
Bits [15:0]: gpi_ov_lvl (Default = 0)
General Purpose Input Over Voltage Level: This is an alarm threshold for the GPI pin. If enabled, the GPI pin voltage rising above this level will trigger an alarm and an SMBALERT. 182.8µV per LSB
 
vin_uv_lvl_reg   Address: 0x0C (R/W)
Bits [15:0]: vin_uv_lvl (Default = 0)
VIN Under Voltage Level: This is an alarm threshold for the input voltage. If enabled, the input pin voltage falling below this level will trigger an alarm and an SMBALERT. 2.19mV per LSB
 
vin_ov_lvl_reg   Address: 0x0D (R/W)
Bits [15:0]: vin_ov_lvl (Default = 0)
VIN Over Voltage Level: This is an alarm threshold for the input voltage. If enabled, the input pin voltage rising above this level will trigger an alarm and an SMBALERT. 2.19mV per LSB
 
vcap_uv_lvl_reg   Address: 0x0E (R/W)
Bits [15:0]: vcap_uv_lvl (Default = 0)
VCAP Under Voltage Level: This is an alarm threshold for the capacitor stack voltage. If enabled, the VCAP pin voltage falling below this level will trigger an alarm and an SMBALERT. 1.46mV per LSB
 
vcap_ov_lvl_reg   Address: 0x0F (R/W)
Bits [15:0]: vcap_ov_lvl (Default = 0)
VCAP Over Voltage Level: This is an alarm threshold for the capacitor stack voltage. If enabled, the VCAP pin voltage rising above this level will trigger an alarm and an SMBALERT. 1.46mV per LSB
 
vout_uv_lvl_reg   Address: 0x10 (R/W)
Bits [15:0]: vout_uv_lvl (Default = 0)
VOUT Under Voltage Level: This is an alarm threshold for the output voltage. If enabled, the VOUT pin voltage falling below this level will trigger an alarm and an SMBALERT. 2.19mV per LSB
 
vout_ov_lvl_reg   Address: 0x11 (R/W)
Bits [15:0]: vout_ov_lvl (Default = 0)
VOUT Over Voltage Level: This is an alarm threshold for the output voltage. If enabled, the VOUT pin voltage rising above this level will trigger an alarm and an SMBALERT. 2.19mV per LSB
 
dtemp_cold_lvl_reg   Address: 0x12 (R/W)
Bits [15:0]: dtemp_cold_lvl (Default = 0)
Die Temperature Cold Level: This is an alarm threshold for the die temperature. If enabled, the die temperature falling below this level will trigger an alarm and an SMBALERT. Temperature = 0.0295C per LSB - 274C
 
dtemp_hot_lvl_reg   Address: 0x13 (R/W)
Bits [15:0]: dtemp_hot_lvl (Default = 0)
Die Temperature Hot Level: This is an alarm threshold for the die temperature. If enabled, the die temperature rising above this level will trigger an alarm and an SMBALERT. Temperature = 0.0295C per LSB - 274C
 
ichg_uc_lvl_reg   Address: 0x14 (R/W)
Bits [15:0]: ichg_uc_lvl (Default = 0)
Charge Undercurrent Level: This is an alarm threshold for the charge current. If enabled, the charge current falling below this level will trigger an alarm and an SMBALERT. 1.955µV/Rsnsc per LSB
 
iin_oc_lvl_reg   Address: 0x15 (R/W)
Bits [15:0]: iin_oc_lvl (Default = 0)
Input Overcurrent Level: This is an alarm threshold for the input current. If enabled, the input current rising above this level will trigger an alarm and an SMBALERT. 1.955µV/Rsnsi per LSB
 
cap_uv_lvl_reg   Address: 0x16 (R/W)
Bits [15:0]: cap_uv_lvl (Default = 0)
Capacitor Under Voltage Level: This is an alarm threshold for each individual capacitor voltage in the stack. If enabled, any capacitor voltage falling below this level will trigger an alarm and an SMBALERT. 182.8µV per LSB.
 
cap_ov_lvl_reg   Address: 0x17 (R/W)
Bits [15:0]: cap_ov_lvl (Default = 0)
Capacitor Over Voltage Level: This is an alarm threshold for each individual capacitor in the stack. If enabled, any capacitor voltage rising above this level will trigger an alarm and an SMBALERT. 182.8µV per LSB
 
cap_lo_lvl_reg   Address: 0x18 (R/W)
Bits [15:0]: cap_lo_lvl (Default = 0)
Capacitance Low Level: This is an alarm threshold for the measured stack capacitance. If the measured stack capacitance is less than this level it will trigger an alarm and an SMBALERT, if enabled. When ctl_cap_scale is set to 1, capacitance is 3.36µF * RT/RTST per LSB. When ctl_cap_scale is set to 0 it is 336µF * RT/RTST per LSB.
 
esr_hi_lvl_reg   Address: 0x19 (R/W)
Bits [15:0]: esr_hi_lvl (Default = 0)
ESR High Level: This is an alarm threshold for the measured stack ESR. If enabled, a measurement of stack ESR exceeding this level will trigger an alarm and an SMBALERT. Rsnsc/64 per LSB.
 
esr_i_on_settling_reg   Address: 0x1A (R/W)
Bits [15:0]: esr_i_on_settling (Default = 2)
Time to allow the charging current to settle before measuring the charge voltage and current for ESR. Each LSB is 1024 switcher periods.
 
esr_i_off_settling_reg   Address: 0x1B (R/W)
Bits [15:0]: esr_i_off_settling (Default = 8)
Time to wait after turning the charge current off before measuring the charge voltage and current for ESR. Each LSB is 1024 switcher periods.
 
esr_i_override_reg   Address: 0x1C (R/W)
Bits [15:0]: esr_i_override (Default = 0)
This value overrides the LTC3351's adaptive test current selection for the ESR test. If this register is non-zero, the lower 8 bits will be used as an 8 bit DAC value to set the charge current during the ESR test. Typically this register will not need to be set. ITEST = 32mV * (esr_i_override[7:0] + 1) / 256 / Rsnsc
 
cap_i_on_settling_reg   Address: 0x1D (R/W)
Bits [15:0]: cap_i_on_settling (Default = 8)
Time to wait after turning the test current on before measuring the first voltage of the capacitance measurement. Each LSB is 1024 switcher periods.
 
cap_delta_v_setting_reg   Address: 0x1E (R/W)
Bits [15:0]: cap_delta_v_setting (Default = 550)
The target delta V for the capacitance test. The scale is 182.8µV per LSB. The default is approximately 100mV.
 
min_boost_cap_voltage_reg   Address: 0x1F (R/W)
Bits [15:0]: min_boost_cap_voltage (Default = 0)
If this register is non-zero, it sets the minimum capacitor voltage the boost will operate at. If any capacitor voltage falls below this value in boost mode the boost will be forced off, the boost will not turn back on even if the capacitor voltage rises above this voltage. Only after input power returns will the boost be re-enabled. This prevents the boost from cycling on and off many times once the capacitors' voltage has discharged to the point it can no longer support the system load through the boost. To use this feature vcap[1:num_caps+1] measurements must be enabled in backup mode, see adc_backup_ch_en_reg. Also the capacitor voltages are only measured as often as set by adc_wait_backup.
 
min_vout_hs_disable_reg   Address: 0x20 (R/W)
Bits [15:0]: min_vout_hs_disable (Default = 0)
If this register is non-zero, it sets the minimum voltage VOUT is allowed to reach while the HotSwap is disabled. If the voltage falls below this level the ctl_hotswap_disable bit will be cleared, re-enabling the HotSwap controller. To use this feature the VOUT measurement must be enabled in boost mode, see adc_backup_ch_en_reg. Also the VOUT voltage is only measured as often as set by adc_wait_backup.
 
alarm_reg   Address: 0x23 (R/W)
Alarms Register: A one in any bit in the register indicates its respective alarm has triggered. All bits are active high. Alarms are cleared by clearing (writing 0) the appropriate bit in this register. Setting (writing 1) bits has no effect. For example to clear the alarm_gpi_uv alarm, write 0xFFFD.
Bit 0: alarm_gpi_uv (Default = 0)
GPI Under Voltage alarm
Bit 1: alarm_gpi_ov (Default = 0)
GPI Over Voltage alarm
Bit 2: alarm_vin_uv (Default = 0)
VIN Under Voltage alarm
Bit 3: alarm_vin_ov (Default = 0)
VIN Over Voltage alarm
Bit 4: alarm_vcap_uv (Default = 0)
VCAP Under Voltage alarm
Bit 5: alarm_vcap_ov (Default = 0)
VCAP Over Voltage alarm
Bit 6: alarm_vout_uv (Default = 0)
VOUT Under Voltage alarm
Bit 7: alarm_vout_ov (Default = 0)
VOUT Over Voltage alarm
Bit 8: alarm_dtemp_cold (Default = 0)
Die temperature cold alarm
Bit 9: alarm_dtemp_hot (Default = 0)
Die temperature hot alarm
Bit 10: alarm_ichg_uc (Default = 0)
Charge undercurrent alarm
Bit 11: alarm_iin_oc (Default = 0)
Input overcurrent alarm
Bit 12: alarm_cap_uv (Default = 0)
Capacitor Under Voltage alarm
Bit 13: alarm_cap_ov (Default = 0)
Capacitor Over Voltage alarm
Bit 14: alarm_cap_lo (Default = 0)
Capacitance low alarm
Bit 15: alarm_esr_hi (Default = 0)
ESR high alarm
 
monitor_status_reg   Address: 0x24 (R)
Monitor Status: This register provides real time status information about the state of the monitoring system. Each bit is active high.
Bit 0: mon_meas_active
Capacitance/ESR measurement is active. This bit becomes one at the begining of a capacitance/ESR measurement and remains 1 after the measurement has completed until the capacitors have been discharged back to their regulation voltage.
Bit 1: mon_capesr_scheduled
Indicates that the LTC3351 is waiting programmed time to begin a capacitance/ESR measurement
Bit 2: mon_capesr_pending
Indicates that the LTC3351 is waiting for satisfactory conditions to begin a capacitance/ESR measurement
Bit 3: mon_cap_done
Indicates that the capacitance measurement has completed
Bit 4: mon_esr_done
Indicates that the ESR Measurement has completed
Bit 5: mon_meas_failed
Indicates the last attempted capacitance and ESR measurement was unable to complete
Bit 6: mon_boost_shutdown
This bit is set in boost mode when any capacitor falls below min_boost_cap_voltage_reg. It is cleared when power returns.
Bit 7: mon_disable_charger
Indicates the capacitance and ESR measurement system has temporarily disabled the charger.
Bit 8: mon_cap_meas_active
Indicates the capacitance and ESR measurement system is measuring capacitance.
Bit 9: mon_esr_meas_active
Indicates the capacitance and ESR measurement system is measuring ESR.
Bit 10: mon_power_failed
This bit is set when VIN is outside the UV/OV range or the HotSwap controller is disabled by setting the ctl_hotswap_disable. It is cleared only when mon_power_returned is set.
Bit 11: mon_power_returned
This bit is set when the output is powered by the input and the charger is able to charge. It is cleared only when mon_power_failed is set.
Bit 12: mon_balancing
Indicates the LTC3351 is balancing the capacitor voltage.
Bit 13: mon_shunting
Indicates a capacitor voltage is approaching vshunt and a shunt is turned on.
Bit 14: mon_cap_precharge
Indicates the capacitor stack is being precharged for a capacitance measurement.
Bit 15: mon_reset
This bit is set during a power on reset. It is cleared on any I2C/SMBus write. It can be used to determine if the chip has reset during a power loss followed by a power return.
 
meas_gpi_reg   Address: 0x25 (R)
Bits [15:0]: meas_gpi
Measurement of GPI pin voltage. 182.8µV per LSB
 
meas_vin_reg   Address: 0x26 (R)
Bits [15:0]: meas_vin
Measured Input Voltage. 2.19mV per LSB
 
meas_vcap_reg   Address: 0x27 (R)
Bits [15:0]: meas_vcap
Measured Capacitor Stack Voltage. 1.46mV per LSB.
 
meas_vout_reg   Address: 0x28 (R)
Bits [15:0]: meas_vout
Measured Output Voltage. 2.19mV per LSB.
 
meas_dtemp_reg   Address: 0x29 (R)
Bits [15:0]: meas_dtemp
Measured die temperature. Temperature = 0.0295°C per LSB - 274°C.
 
meas_ichg_reg   Address: 0x2A (R)
Bits [15:0]: meas_ichg
Measured Charge Current. 1.955µV/Rsnsc per LSB
 
meas_iin_reg   Address: 0x2B (R)
Bits [15:0]: meas_iin
Measured Input Current. 1.955µV/Rsnsi per LSB
 
lo_vcap_reg   Address: 0x2C (R)
Bits [15:0]: lo_vcap
The lowest measured capacitor voltage from the last measurement set.
 
hi_vcap_reg   Address: 0x2D (R)
Bits [15:0]: hi_vcap
The highest measured capacitor voltage from the last measurement set.
 
meas_cap_reg   Address: 0x2E (R)
Bits [15:0]: meas_cap
Measured capacitor stack capacitance value. When ctl_cap_scale is set to 1, capacitance is 3.36µF * RT/RTST per LSB. When ctl_cap_scale is set to 0 it is 336µF * RT/RTST per LSB.
 
meas_esr_reg   Address: 0x2F (R)
Bits [15:0]: meas_esr
Measured capacitor stack equivalent series resistance (ESR) value. Rsnsc/64 per LSB
 
meas_vcap1_reg   Address: 0x30 (R)
Bits [15:0]: meas_vcap1
Measured voltage between the CAP1 and CAPRTN pins. 182.8µV per LSB
 
meas_vcap2_reg   Address: 0x31 (R)
Bits [15:0]: meas_vcap2
Measured voltage between the CAP2 and CAP1 pins. 182.8µV per LSB
 
meas_vcap3_reg   Address: 0x32 (R)
Bits [15:0]: meas_vcap3
Measured voltage between the CAP3 and CAP2 pins. 182.8µV per LSB
 
meas_vcap4_reg   Address: 0x33 (R)
Bits [15:0]: meas_vcap4
Measured voltage between the CAP4 and CAP3 pins. 182.8µV per LSB. When the ITST current is on, either due to ctl_force_itst_on or during a capacitance measurement, this voltage measurement will temporarily be low due to the ITST current flowing in the shunt resistor.
 
cap_m0_vc1_reg   Address: 0x34 (R)
Bits [15:0]: cap_m0_vc1
The voltage change on cap1 due to the capacitance measurement. The relative voltage change on each capacitor during the capacitance measurement and the total capacitance can be used to calculate the capacitance of each individual capacitor.
 
cap_m0_vc2_reg   Address: 0x35 (R)
Bits [15:0]: cap_m0_vc2
The voltage change on cap2 due to the capacitance measurement. The relative voltage change on each capacitor during the capacitance measurement and the total capacitance can be used to calculate the capacitance of each individual capacitor.
 
cap_m0_vc3_reg   Address: 0x36 (R)
Bits [15:0]: cap_m0_vc3
The voltage change on cap3 due to the capacitance measurement. The relative voltage change on each capacitor during the capacitance measurement and the total capacitance can be used to calculate the capacitance of each individual capacitor.
 
cap_m0_vc4_reg   Address: 0x37 (R)
Bits [15:0]: cap_m0_vc4
The voltage change on cap4 due to the capacitance measurement. The relative voltage change on each capacitor during the capacitance measurement and the total capacitance can be used to calculate the capacitance of each individual capacitor.
 
esr_m0_vc1_reg   Address: 0x38 (R)
Bits [15:0]: esr_m0_vc1
A measurement of VCAP1 just before turning current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m0_vc2_reg   Address: 0x39 (R)
Bits [15:0]: esr_m0_vc2
A measurement of VCAP2 just before turning current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m0_vc3_reg   Address: 0x3A (R)
Bits [15:0]: esr_m0_vc3
A measurement of VCAP3 just before turning current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m0_vc4_reg   Address: 0x3B (R)
Bits [15:0]: esr_m0_vc4
A measurement of VCAP4 just before turning current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m1_vc1_reg   Address: 0x3C (R)
Bits [15:0]: esr_m1_vc1
The first VCAP1 voltage measurement with charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m1_vc2_reg   Address: 0x3D (R)
Bits [15:0]: esr_m1_vc2
The first VCAP2 voltage measurement with charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m1_vc3_reg   Address: 0x3E (R)
Bits [15:0]: esr_m1_vc3
The first VCAP3 voltage measurement with charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m1_vc4_reg   Address: 0x3F (R)
Bits [15:0]: esr_m1_vc4
The first VCAP4 voltage measurement with charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m1_i_reg   Address: 0x40 (R)
Bits [15:0]: esr_m1_i
The first charge current measurement with charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m2_vc1_reg   Address: 0x41 (R)
Bits [15:0]: esr_m2_vc1
The second VCAP1 voltage measurement with the charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m2_vc2_reg   Address: 0x42 (R)
Bits [15:0]: esr_m2_vc2
The second VCAP2 voltage measurement with the charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m2_vc3_reg   Address: 0x43 (R)
Bits [15:0]: esr_m2_vc3
The second VCAP3 voltage measurement with the charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m2_vc4_reg   Address: 0x44 (R)
Bits [15:0]: esr_m2_vc4
The second VCAP4 voltage measurement with the charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m2_i_reg   Address: 0x45 (R)
Bits [15:0]: esr_m2_i
The second charge current measurement with charge current on for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m3_vc1_reg   Address: 0x46 (R)
Bits [15:0]: esr_m3_vc1
The VCAP1 voltage measurement with charge current off for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m3_vc2_reg   Address: 0x47 (R)
Bits [15:0]: esr_m3_vc2
The VCAP2 voltage measurement with charge current off for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m3_vc3_reg   Address: 0x48 (R)
Bits [15:0]: esr_m3_vc3
The VCAP3 voltage measurement with charge current off for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m3_vc4_reg   Address: 0x49 (R)
Bits [15:0]: esr_m3_vc4
The VCAP4 voltage measurement with charge current off for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
esr_m3_i_reg   Address: 0x4A (R)
Bits [15:0]: esr_m3_i
The charge current measurement with charge current off for the ESR measurement. This value is used by the LTC3351 in the calculation of meas_esr.
 
rev_reg   Address: 0x50 (R)
Bits [15:0]: rev_code
The LTC3351 revision code.
 
next_ichrg_control_test_current   Address: 0x54 (R)
Bits [7:0]: next_esr_i
The 8 bit DAC setting for the charge current that the LTC3351 has calculated for the next ESR measurement based on the previous ESR measurement. The first ESR measurement will use a setting of 32. If esr_i_override is non-zero, this register will be calculated but esr_i_override will be used instead. If non-zero ITEST = 32mV * (next_esr_i[7:0] + 1) / 256 / Rsnsc
 
num_caps_reg   Address: 0xED (R)
Bits [1:0]: num_caps
Number of Capacitors. This register shows the state of the CAP_SLCT1, CAP_SLCT0 pins. The value read in this register is the number of capacitors programmed minus one.
 
sys_status   Address: 0xEE (R)
System Status Register: This register provides real time status information about the instantaneous state of the system. Each bit is active high.
Bit 0: stepdown_mode
The synchronous controller is in step-down mode (charging)
Bit 1: stepup_mode
The synchronous controller is in step-up mode (backup)
Bit 2: chrg_cv
The charger is in constant voltage mode
Bit 3: chrg_uvlo
The charger is in under-voltage lockout or has been disabled by ctl_force_charger_off.
Bit 4: chrg_input_ilim
The charger is in input current limit
Bit 5: cappg
The capacitor voltage is above power good threshold
Bit 7: boost_en
Indicates the boost is enabled
Bit 8: buck_en
Indicates the charger is enabled
Bit 9: chrg_ci
Indicates the charger is in constant current mode
Bit 11: vingd
Indicates the input voltage is inside the UV/OV range.