Industrial and Sensor ICs
Volume 9, Issue 4 YOUR SEMICONDUCTOR SOLUTIONS RESOURCE

Simple Sequencer® Provides a Flexible, Cost-Effective Solution for Power Supply Sequencing

Today's complex systems often require two to four voltage rails to be sequenced. These voltages need to be monitored accurately and then powered up in the correct sequence while ensuring the correct timing delay between each of the voltage rails. If the power supply voltage drops below the threshold, the system can shut down, potentially causing a loss of data. The ADM6820 and ADM1086 power supply sequencing ICs can accurately and reliably sequence power rails. The outputs are asserted after programmable turn-on delays, enabling the ADP121 and ADP130 linear regulators in the desired sequence. The thresholds are established by resistor ratios; the delay is established by a capacitor.

To learn more about ADI's family of linear regulators, go to www.analog.com/LDO.

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Typical Power Sequencing Schematic

Part
Number
Number of
Supplies
Monitored
Number
Output
Drivers
Output
Type
Sequencing Package Price
($U.S.)*
ADM1085 1: Cascadable 1 Active low,
open-drain
Sequence up, cap programmable 6-lead SC70 0.34
ADM1086 1: Cascadable 1 Active low,
push-pull
Sequence up, cap programmable 6-lead SC70 0.34
ADM1087 1: Cascadable 1 Active low,
open-drain
Sequence up, cap programmable 6-lead SC70 0.34
ADM6819 2: Cascadable 1 FET Drive Sequence up, 300 ms fixed delay 6-lead SOT-23 1.21
ADM6820 2: Cascadable 1 FET Drive Sequence up, cap programmable 6-lead SOT-23 1.21

*Denotes quantities between 1000-4999.

Single and Multichannel Voltage Supervisors and Watchdog Timers Deliver Increased Accuracy and System Reliability

The number of voltage rails in complex systems has increased dramatically in recent years. A single board may comprise microprocessors, FPGAs, and ASICs, along with analog and digital circuit elements. Monitoring of the ever increasing number of voltage rails is fundamental for the safe, robust, and reliable operation of the system over its lifetime. As the number of voltage rails increases, the probability of a fault occurring increases proportionately. ADI's family of high accuracy multivoltage monitors offer a simple, precise, cost-efficient method of ensuring reliable operation in complex multivoltage systems, while dramatically reducing required board space.

Part
Number
Num-
ber of
Moni-
tored
Volt-
ages
Reset
Thres-
hold
Summ-
ary (V)
Thres-
hold
Ac-
cu-
racy
(%)
Min
Reset
Time-
out (ms)
Reset
Output
-Stage
Manual
Reset
Capa-
bility
Typ
Watch-
dog
Timeout (ms)
Package Price
($U.S.)*
ADM809 1 2.32 to 4.63 4 140 Active low,
push-pull
No 3-lead SC70,
3-lead SOT-23
0.63
ADM6320 1 2.5 to 5.0 2.5 1, 20, 140, 1120 Active low,
open-drain
Yes 6.3/ 102/ 1600/ 25,600 5-lead SOT-23 0.51
ADM13305 2 0.6 (adj),
1.68 to 4.55
0.8 140 Active high,
push-pull,
Active low,
push-pull
Yes 1600 8-lead SOIC 0.96
ADM13307 3 0.6 (adj),
1.25 (adj),
1.68 to 4.55
0.8 140 Active high,
push-pull,
Active low,
push-pull
Yes 8-lead SOIC 0.99

*Denotes quantities between 1000-4999.

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