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LTC2666.h File Reference
Digital-to-Analog Converters (DAC) » LTC2666 8-Channel SPI 16-/12-Bit +/-10V Vout SoftSpan DACs with 10ppm/C Max Reference

LTC2666: 8-Channel SPI 16-/12-Bit +/-10V Vout SoftSpan DACs with 10ppm/C Max Reference. More...

## Detailed Description

LTC2666: 8-Channel SPI 16-/12-Bit +/-10V Vout SoftSpan DACs with 10ppm/C Max Reference.

    The LTC2666 is a family of 8-channel, 12/16-bit +/-10V digital-to-analog converters with integrated
    precision references. They are guaranteed monotonic and have built-in rail-to-rail output buffers.
    These SoftSpan DACs offer five output ranges up to +/-10V. The range of each channel is independently
    programmable, or the part can be hardware-configured for operation in a fixed range.

    The integrated 2.5V reference is buffered separately to each channel; an external reference can be used
    for additional range options. The LTC2668 also includes toggle capability - alternating codes via the
    software toggle command, or by providing a free-running clock to the TGP pin.

    The SPI/Microwire-compatible 3-wire serial interface operates on logic levels as low as 1.71V, at clock
    rates up to 50MHz.

     SPI DATA FORMAT (MSB First):

     24-Bit Load Sequence:

                  Byte #1                       Byte #2                       Byte #3
                  Command                   MSB                             LSB
     LTC2666-16 : C3 C2 C1 C0 A3 A2 A1 A0   D15 D14 D13 D12 D11 D10 D9 D8   D7 D6 D5 D4 D3 D2 D1 D0
     LTC2666-12 : C3 C2 C1 C0 A3 A2 A1 A0   D11 D10 D9  D8  D7  D6  D5 D4   D3 D2 D1 D0 X  X  X  X

     32-Bit Load Sequence:
                  Byte #1                       Byte #2                       Byte #3                 Byte #4
                  Command                   MSB                             LSB
     LTC2666-16 : X  X  X  X  X  X  X  X    C3 C2 C1 C0 A3 A2 A1 A0   D15 D14 D13 D12 D11 D10 D9 D8   D7 D6 D5 D4 D3 D2 D1 D0
     LTC2666-12 : X  X  X  X  X  X  X  X    C3 C2 C1 C0 A3 A2 A1 A0   D11 D10 D9  D8  D7  D6  D5 D4   D3 D2 D1 D0 X  X  X  X

     Cx   : DAC Command Code
     Ax   : DAC Address (0 to F, corresponding to DAC 0 to DAC 15)
     Dx   : DAC Data Bits
     X    : Don't care

http://www.linear.com/product/LTC2666

http://www.linear.com/product/LTC2666#demoboards

Copyright 2018(c) Analog Devices, Inc.

All rights reserved.

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Header for LTC2666: 8-Channel SPI 16-/12-Bit +/-10V Vout SoftSpan DACs with 10ppm/C Max Reference

Definition in file LTC2666.h.

Go to the source code of this file.

## Functions
int8_t | LTC2666_write (uint8_t cs, uint8_t dac_command, uint8_t dac_address, uint16_t dac_code)
| Write the 16-bit dac_code to the LTC2666. More...
uint16_t | LTC2666_voltage_to_code (float dac_voltage, float min_output, float max_output)
| Calculate a LTC2666 DAC code given the desired output voltage and DAC address (0-3) More...
float | LTC2666_code_to_voltage (uint16_t dac_code, float min_output, float max_output)
| Calculate the LTC2666 DAC output voltage given the DAC code, offset, and LSB. More...

## Macros
#define | LTC2666_CS QUIKEVAL_CS
| Define the SPI CS pin. More...
LTC2666 Command Codes
OR'd together with the DAC address to form the command byte
#define | LTC2666_CMD_WRITE_N 0x00
| Write to input register n. More...
#define | LTC2666_CMD_UPDATE_N 0x10
| Update (power up) DAC register n. More...
#define | LTC2666_CMD_WRITE_N_UPDATE_ALL 0x20
| Write to input register n, update (power-up) all. More...
#define | LTC2666_CMD_WRITE_N_UPDATE_N 0x30
| Write to input register n, update (power-up) More...
#define | LTC2666_CMD_POWER_DOWN_N 0x40
| Power down n. More...
#define | LTC2666_CMD_POWER_DOWN_ALL 0x50
| Power down chip (all DAC's, MUX and reference) More...
#define | LTC2666_CMD_SPAN 0x60
| Write span to dac n. More...
#define | LTC2666_CMD_CONFIG 0x70
| Configure reference / toggle. More...
#define | LTC2666_CMD_WRITE_ALL 0x80
| Write to all input registers. More...
#define | LTC2666_CMD_UPDATE_ALL 0x90
| Update all DACs. More...
#define | LTC2666_CMD_WRITE_ALL_UPDATE_ALL 0xA0
| Write to all input reg, update all DACs. More...
#define | LTC2666_CMD_MUX 0xB0
| Select MUX channel (controlled by 5 LSbs in data word) More...
#define | LTC2666_CMD_TOGGLE_SEL 0xC0
| Select which DACs can be toggled (via toggle pin or global toggle bit) More...
#define | LTC2666_CMD_GLOBAL_TOGGLE 0xD0
| Software toggle control via global toggle bit. More...
#define | LTC2666_CMD_SPAN_ALL 0xE0
| Set span for all DACs. More...
#define | LTC2666_CMD_NO_OPERATION 0xF0
| No operation. More...
LTC2666 Span Codes
Descriptions are valid for a 2.5V reference. These can also be interpreted as 0 to 2*Vref, 0 to 4*Vref, etc. when an external reference other than 2.5V is used.
#define | LTC2666_SPAN_0_TO_5V 0x0000
#define | LTC2666_SPAN_0_TO_10V 0x0001
#define | LTC2666_SPAN_PLUS_MINUS_5V 0x0002
#define | LTC2666_SPAN_PLUS_MINUS_10V 0x0003
#define | LTC2666_SPAN_PLUS_MINUS_2V5 0x0004
LTC2666 Configuration options
Used in conjunction with LTC2666_CMD_CONFIG command
#define | LTC2666_REF_DISABLE 0x0001
#define | LTC2666_THERMAL_SHUTDOWN 0x0002
LTC2666 MUX enable
Used in conjunction with LTC2666_CMD_MUX command
#define | LTC2666_MUX_DISABLE 0x0000
#define | LTC2666_MUX_ENABLE 0x0010
LTC2666 Global Toggle
Used in conjunction with LTC2666_CMD_GLOBAL_TOGGLE command, affects DACs whose Toggle Select bits have been set to 1
#define | LTC2666_TOGGLE_REG_A 0x0000
#define | LTC2666_TOGGLE_REG_B 0x0010

## Variables
LTC2666 Minimums and Maximums for each Span
Lookup tables for minimum and maximum outputs for a given span
const float | LTC2666_MIN_OUTPUT [5] = {0.0, 0.0, -5.0, -10.0, -2.5}
const float | LTC2666_MAX_OUTPUT [5] = {5.0, 10.0, 5.0, 10.0, 2.5}

## Function Documentation

## ◆ LTC2666_code_to_voltage()

float LTC2666_code_to_voltage | ( | uint16_t | dac_code,
|  | float | min_output,
|  | float | max_output
| ) |  |

Calculate the LTC2666 DAC output voltage given the DAC code, offset, and LSB.

Returns
  the output voltage

Definition at line 117 of file LTC2666.cpp.

## ◆ LTC2666_voltage_to_code()

uint16_t LTC2666_voltage_to_code | ( | float | dac_voltage,
|  | float | min_output,
|  | float | max_output
| ) |  |

Calculate a LTC2666 DAC code given the desired output voltage and DAC address (0-3)

Returns
  The 16 bit code to send to the DAC

Definition at line 103 of file LTC2666.cpp.

## ◆ LTC2666_write()

int8_t LTC2666_write | ( | uint8_t | cs,
|  | uint8_t | dac_command,
|  | uint8_t | dac_address,
|  | uint16_t | dac_code
| ) |  |

Write the 16-bit dac_code to the LTC2666.

Returns
  Zero if readback (SDO) data matches the value previously sent, One if mismatched (indicating data error somewhere)

Definition at line 70 of file LTC2666.cpp.

## Macro Definition Documentation

## ◆ LTC2666_CMD_CONFIG

#define LTC2666_CMD_CONFIG 0x70

Configure reference / toggle.

Definition at line 103 of file LTC2666.h.

## ◆ LTC2666_CMD_GLOBAL_TOGGLE

#define LTC2666_CMD_GLOBAL_TOGGLE 0xD0

Software toggle control via global toggle bit.

Definition at line 109 of file LTC2666.h.

## ◆ LTC2666_CMD_MUX

#define LTC2666_CMD_MUX 0xB0

Select MUX channel (controlled by 5 LSbs in data word)

Definition at line 107 of file LTC2666.h.

## ◆ LTC2666_CMD_NO_OPERATION

#define LTC2666_CMD_NO_OPERATION 0xF0

No operation.

Definition at line 111 of file LTC2666.h.

## ◆ LTC2666_CMD_POWER_DOWN_ALL

#define LTC2666_CMD_POWER_DOWN_ALL 0x50

Power down chip (all DAC's, MUX and reference)

Definition at line 100 of file LTC2666.h.

## ◆ LTC2666_CMD_POWER_DOWN_N

#define LTC2666_CMD_POWER_DOWN_N 0x40

Power down n.

Definition at line 99 of file LTC2666.h.

## ◆ LTC2666_CMD_SPAN

#define LTC2666_CMD_SPAN 0x60

Write span to dac n.

Definition at line 102 of file LTC2666.h.

## ◆ LTC2666_CMD_SPAN_ALL

#define LTC2666_CMD_SPAN_ALL 0xE0

Set span for all DACs.

Definition at line 110 of file LTC2666.h.

## ◆ LTC2666_CMD_TOGGLE_SEL

#define LTC2666_CMD_TOGGLE_SEL 0xC0

Select which DACs can be toggled (via toggle pin or global toggle bit)

Definition at line 108 of file LTC2666.h.

## ◆ LTC2666_CMD_UPDATE_ALL

#define LTC2666_CMD_UPDATE_ALL 0x90

Update all DACs.

Definition at line 105 of file LTC2666.h.

## ◆ LTC2666_CMD_UPDATE_N

#define LTC2666_CMD_UPDATE_N 0x10

Update (power up) DAC register n.

Definition at line 96 of file LTC2666.h.

## ◆ LTC2666_CMD_WRITE_ALL

#define LTC2666_CMD_WRITE_ALL 0x80

Write to all input registers.

Definition at line 104 of file LTC2666.h.

## ◆ LTC2666_CMD_WRITE_ALL_UPDATE_ALL

#define LTC2666_CMD_WRITE_ALL_UPDATE_ALL 0xA0

Write to all input reg, update all DACs.

Definition at line 106 of file LTC2666.h.

## ◆ LTC2666_CMD_WRITE_N

#define LTC2666_CMD_WRITE_N 0x00

Write to input register n.

Definition at line 95 of file LTC2666.h.

## ◆ LTC2666_CMD_WRITE_N_UPDATE_ALL

#define LTC2666_CMD_WRITE_N_UPDATE_ALL 0x20

Write to input register n, update (power-up) all.

Definition at line 97 of file LTC2666.h.

## ◆ LTC2666_CMD_WRITE_N_UPDATE_N

#define LTC2666_CMD_WRITE_N_UPDATE_N 0x30

Write to input register n, update (power-up)

Definition at line 98 of file LTC2666.h.

## ◆ LTC2666_CS

#define LTC2666_CS QUIKEVAL_CS

Define the SPI CS pin.

Definition at line 90 of file LTC2666.h.

## ◆ LTC2666_MUX_DISABLE

#define LTC2666_MUX_DISABLE 0x0000

Definition at line 143 of file LTC2666.h.

## ◆ LTC2666_MUX_ENABLE

#define LTC2666_MUX_ENABLE 0x0010

Definition at line 144 of file LTC2666.h.

## ◆ LTC2666_REF_DISABLE

#define LTC2666_REF_DISABLE 0x0001

Definition at line 136 of file LTC2666.h.

## ◆ LTC2666_SPAN_0_TO_10V

#define LTC2666_SPAN_0_TO_10V 0x0001

Definition at line 120 of file LTC2666.h.

## ◆ LTC2666_SPAN_0_TO_5V

#define LTC2666_SPAN_0_TO_5V 0x0000

Definition at line 119 of file LTC2666.h.

## ◆ LTC2666_SPAN_PLUS_MINUS_10V

#define LTC2666_SPAN_PLUS_MINUS_10V 0x0003

Definition at line 122 of file LTC2666.h.

## ◆ LTC2666_SPAN_PLUS_MINUS_2V5

#define LTC2666_SPAN_PLUS_MINUS_2V5 0x0004

Definition at line 123 of file LTC2666.h.

## ◆ LTC2666_SPAN_PLUS_MINUS_5V

#define LTC2666_SPAN_PLUS_MINUS_5V 0x0002

Definition at line 121 of file LTC2666.h.

## ◆ LTC2666_THERMAL_SHUTDOWN

#define LTC2666_THERMAL_SHUTDOWN 0x0002

Definition at line 137 of file LTC2666.h.

## ◆ LTC2666_TOGGLE_REG_A

#define LTC2666_TOGGLE_REG_A 0x0000

Definition at line 151 of file LTC2666.h.

## ◆ LTC2666_TOGGLE_REG_B

#define LTC2666_TOGGLE_REG_B 0x0010

Definition at line 152 of file LTC2666.h.

## Variable Documentation

## ◆ LTC2666_MAX_OUTPUT

const float LTC2666_MAX_OUTPUT[5] = {5.0, 10.0, 5.0, 10.0, 2.5}

Definition at line 130 of file LTC2666.h.

## ◆ LTC2666_MIN_OUTPUT

const float LTC2666_MIN_OUTPUT[5] = {0.0, 0.0, -5.0, -10.0, -2.5}

Definition at line 129 of file LTC2666.h.