Linduino  1.3.0
Linear Technology Arduino-Compatible Demonstration Board

LTC2662: 5-Channel 16-/12-Bit 300mA SoftSpan Current Source DACs. More...

Detailed Description

LTC2662: 5-Channel 16-/12-Bit 300mA SoftSpan Current Source DACs.

The LTC2662 is a family of 5-channel, 16-/12-bit current source digital-to-analog converters with precision
integrated reference and accurate full-scale current. The LTC2662 is guaranteed monotonic and offers independent
SoftSpan programmability of the current output range from 3.125mA to 300mA.

The LTC2662 provides a separate VDD0-4 supply for each OUT0-4 channel. The flexible VDD0-4 supply allows
operation from 2.85V to 33V. Internal 12 ohm switches allow any OUT0-4 pin to be connected to an optional
negative V- supply voltage and sink up to 80mA.

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
 LTC2662-16 : C3 C2 C1 C0 A3 A2 A1 A0   D15 D14 D13 D12 D11 D10 D9 D8   D7 D6 D5 D4 D3 D2 D1 D0
 LTC2662-12 : 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
 LTC2662-16 : 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
 LTC2662-12 : 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/LTC2662

http://www.linear.com/product/LTC2662#demoboards

Copyright 2018(c) Analog Devices, Inc.

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

  • Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
  • Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
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  • The use of this software may or may not infringe the patent rights of one or more patent holders. This license does not release you from the requirement that you obtain separate licenses from these patent holders to use this software.
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Header for LTC2662: 5-Channel 16-/12-Bit 300mA SoftSpan Current Source DACs

Definition in file LTC2662.h.

Go to the source code of this file.

Functions

int8_t LTC2662_write (uint8_t cs, uint8_t dac_command, uint8_t dac_address, uint16_t dac_code)
 Write the 16-bit dac_code to the LTC2662. More...
 
uint16_t LTC2662_current_to_code (float dac_current, float max_output)
 Calculate a LTC2662 DAC code given the desired output current. More...
 
float LTC2662_code_to_current (uint16_t dac_code, float max_output)
 Calculate the LTC2662 DAC output current given the DAC code and max output. More...
 

Macros

#define LTC2662_CS   QUIKEVAL_CS
 Define the SPI CS pin. More...
 
LTC2662 Command Codes

OR'd together with the DAC address to form the command byte

#define LTC2662_CMD_WRITE_N   0x00
 Write to input register n. More...
 
#define LTC2662_CMD_UPDATE_N   0x10
 Update (power up) DAC register n. More...
 
#define LTC2662_CMD_WRITE_N_UPDATE_ALL   0x20
 Write to input register n, update (power-up) all. More...
 
#define LTC2662_CMD_WRITE_N_UPDATE_N   0x30
 Write to input register n, update (power-up) More...
 
#define LTC2662_CMD_POWER_DOWN_N   0x40
 Power down n. More...
 
#define LTC2662_CMD_POWER_DOWN_ALL   0x50
 Power down chip (all DAC's, MUX and reference) More...
 
#define LTC2662_CMD_SPAN   0x60
 Write span to dac n. More...
 
#define LTC2662_CMD_CONFIG   0x70
 Configure reference / toggle. More...
 
#define LTC2662_CMD_WRITE_ALL   0x80
 Write to all input registers. More...
 
#define LTC2662_CMD_UPDATE_ALL   0x90
 Update all DACs. More...
 
#define LTC2662_CMD_WRITE_ALL_UPDATE_ALL   0xA0
 Write to all input reg, update all DACs. More...
 
#define LTC2662_CMD_MUX   0xB0
 Select MUX channel (controlled by 5 LSbs in data word) More...
 
#define LTC2662_CMD_TOGGLE_SEL   0xC0
 Select which DACs can be toggled (via toggle pin or global toggle bit) More...
 
#define LTC2662_CMD_GLOBAL_TOGGLE   0xD0
 Software toggle control via global toggle bit. More...
 
#define LTC2662_CMD_SPAN_ALL   0xE0
 Set span for all DACs. More...
 
#define LTC2662_CMD_NO_OPERATION   0xF0
 No operation. More...
 
LTC2662 Span Codes

Descriptions are valid for a 1.25V reference and 20k R_FSADJ.

#define LTC2662_SPAN_HI_Z   0x0000
 
#define LTC2662_SPAN_3_125MA   0x0001
 
#define LTC2662_SPAN_6_25MA   0x0002
 
#define LTC2662_SPAN_12_5MA   0x0003
 
#define LTC2662_SPAN_25MA   0x0004
 
#define LTC2662_SPAN_50MA   0x0005
 
#define LTC2662_SPAN_100MA   0x0006
 
#define LTC2662_SPAN_200MA   0x0007
 
#define LTC2662_SPAN_SW_TO_NEG_V   0x0008
 
#define LTC2662_SPAN_300MA   0x0009
 
LTC2662 Configuration options

Used in conjunction with LTC2662_CMD_CONFIG command

#define LTC2662_REF_DISABLE   0x0001
 
#define LTC2662_THERMAL_SHUTDOWN   0x0002
 
#define LTC2662_POWERLIMIT_PROTECTION   0x0003
 
#define LTC2662_OPEN_CIRCUIT_DETECT_DISABLE   0x0004
 
LTC2662 Global Toggle

Used in conjunction with LTC2662_CMD_GLOBAL_TOGGLE command, affects DACs whose Toggle Select bits have been set to 1

#define LTC2662_TOGGLE_REG_A   0x0000
 
#define LTC2662_TOGGLE_REG_B   0x0010
 

Variables

LTC2662 Minimums and Maximums for each Span

Lookup tables for minimum and maximum outputs for a given span

const float LTC2662_MIN_OUTPUT [10] = {0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0}
 
const float LTC2662_MAX_OUTPUT [10] = {0.0, 3.125, 6.25, 12.5, 25.0, 50.0, 100.0, 200.0, 0, 300.0}
 

Function Documentation

◆ LTC2662_code_to_current()

float LTC2662_code_to_current ( uint16_t  dac_code,
float  max_output 
)

Calculate the LTC2662 DAC output current given the DAC code and max output.

Returns
the output voltage
Parameters
dac_codeDAC code value
max_outputFull scale current

Definition at line 102 of file LTC2662.cpp.

◆ LTC2662_current_to_code()

uint16_t LTC2662_current_to_code ( float  dac_current,
float  max_output 
)

Calculate a LTC2662 DAC code given the desired output current.

Returns
The 16 bit code to send to the DAC
Parameters
dac_currentDesired current
max_outputFull scale current

Definition at line 88 of file LTC2662.cpp.

◆ LTC2662_write()

int8_t LTC2662_write ( uint8_t  cs,
uint8_t  dac_command,
uint8_t  dac_address,
uint16_t  dac_code 
)

Write the 16-bit dac_code to the LTC2662.

Returns
Zero if readback (SDO) data matches the value previously sent, One if mismatched (indicating data error somewhere)
Parameters
csChip select
dac_commandDAC command word
dac_addressDAC channel address
dac_code2 byte dac code

Definition at line 70 of file LTC2662.cpp.

Macro Definition Documentation

◆ LTC2662_CMD_CONFIG

#define LTC2662_CMD_CONFIG   0x70

Configure reference / toggle.

Definition at line 102 of file LTC2662.h.

◆ LTC2662_CMD_GLOBAL_TOGGLE

#define LTC2662_CMD_GLOBAL_TOGGLE   0xD0

Software toggle control via global toggle bit.

Definition at line 108 of file LTC2662.h.

◆ LTC2662_CMD_MUX

#define LTC2662_CMD_MUX   0xB0

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

Definition at line 106 of file LTC2662.h.

◆ LTC2662_CMD_NO_OPERATION

#define LTC2662_CMD_NO_OPERATION   0xF0

No operation.

Definition at line 110 of file LTC2662.h.

◆ LTC2662_CMD_POWER_DOWN_ALL

#define LTC2662_CMD_POWER_DOWN_ALL   0x50

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

Definition at line 99 of file LTC2662.h.

◆ LTC2662_CMD_POWER_DOWN_N

#define LTC2662_CMD_POWER_DOWN_N   0x40

Power down n.

Definition at line 98 of file LTC2662.h.

◆ LTC2662_CMD_SPAN

#define LTC2662_CMD_SPAN   0x60

Write span to dac n.

Definition at line 101 of file LTC2662.h.

◆ LTC2662_CMD_SPAN_ALL

#define LTC2662_CMD_SPAN_ALL   0xE0

Set span for all DACs.

Definition at line 109 of file LTC2662.h.

◆ LTC2662_CMD_TOGGLE_SEL

#define LTC2662_CMD_TOGGLE_SEL   0xC0

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

Definition at line 107 of file LTC2662.h.

◆ LTC2662_CMD_UPDATE_ALL

#define LTC2662_CMD_UPDATE_ALL   0x90

Update all DACs.

Definition at line 104 of file LTC2662.h.

◆ LTC2662_CMD_UPDATE_N

#define LTC2662_CMD_UPDATE_N   0x10

Update (power up) DAC register n.

Definition at line 95 of file LTC2662.h.

◆ LTC2662_CMD_WRITE_ALL

#define LTC2662_CMD_WRITE_ALL   0x80

Write to all input registers.

Definition at line 103 of file LTC2662.h.

◆ LTC2662_CMD_WRITE_ALL_UPDATE_ALL

#define LTC2662_CMD_WRITE_ALL_UPDATE_ALL   0xA0

Write to all input reg, update all DACs.

Definition at line 105 of file LTC2662.h.

◆ LTC2662_CMD_WRITE_N

#define LTC2662_CMD_WRITE_N   0x00

Write to input register n.

Definition at line 94 of file LTC2662.h.

◆ LTC2662_CMD_WRITE_N_UPDATE_ALL

#define LTC2662_CMD_WRITE_N_UPDATE_ALL   0x20

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

Definition at line 96 of file LTC2662.h.

◆ LTC2662_CMD_WRITE_N_UPDATE_N

#define LTC2662_CMD_WRITE_N_UPDATE_N   0x30

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

Definition at line 97 of file LTC2662.h.

◆ LTC2662_CS

#define LTC2662_CS   QUIKEVAL_CS

Define the SPI CS pin.

Definition at line 89 of file LTC2662.h.

◆ LTC2662_OPEN_CIRCUIT_DETECT_DISABLE

#define LTC2662_OPEN_CIRCUIT_DETECT_DISABLE   0x0004

Definition at line 141 of file LTC2662.h.

◆ LTC2662_POWERLIMIT_PROTECTION

#define LTC2662_POWERLIMIT_PROTECTION   0x0003

Definition at line 140 of file LTC2662.h.

◆ LTC2662_REF_DISABLE

#define LTC2662_REF_DISABLE   0x0001

Definition at line 138 of file LTC2662.h.

◆ LTC2662_SPAN_100MA

#define LTC2662_SPAN_100MA   0x0006

Definition at line 122 of file LTC2662.h.

◆ LTC2662_SPAN_12_5MA

#define LTC2662_SPAN_12_5MA   0x0003

Definition at line 119 of file LTC2662.h.

◆ LTC2662_SPAN_200MA

#define LTC2662_SPAN_200MA   0x0007

Definition at line 123 of file LTC2662.h.

◆ LTC2662_SPAN_25MA

#define LTC2662_SPAN_25MA   0x0004

Definition at line 120 of file LTC2662.h.

◆ LTC2662_SPAN_300MA

#define LTC2662_SPAN_300MA   0x0009

Definition at line 125 of file LTC2662.h.

◆ LTC2662_SPAN_3_125MA

#define LTC2662_SPAN_3_125MA   0x0001

Definition at line 117 of file LTC2662.h.

◆ LTC2662_SPAN_50MA

#define LTC2662_SPAN_50MA   0x0005

Definition at line 121 of file LTC2662.h.

◆ LTC2662_SPAN_6_25MA

#define LTC2662_SPAN_6_25MA   0x0002

Definition at line 118 of file LTC2662.h.

◆ LTC2662_SPAN_HI_Z

#define LTC2662_SPAN_HI_Z   0x0000

Definition at line 116 of file LTC2662.h.

◆ LTC2662_SPAN_SW_TO_NEG_V

#define LTC2662_SPAN_SW_TO_NEG_V   0x0008

Definition at line 124 of file LTC2662.h.

◆ LTC2662_THERMAL_SHUTDOWN

#define LTC2662_THERMAL_SHUTDOWN   0x0002

Definition at line 139 of file LTC2662.h.

◆ LTC2662_TOGGLE_REG_A

#define LTC2662_TOGGLE_REG_A   0x0000

Definition at line 148 of file LTC2662.h.

◆ LTC2662_TOGGLE_REG_B

#define LTC2662_TOGGLE_REG_B   0x0010

Definition at line 149 of file LTC2662.h.

Variable Documentation

◆ LTC2662_MAX_OUTPUT

const float LTC2662_MAX_OUTPUT[10] = {0.0, 3.125, 6.25, 12.5, 25.0, 50.0, 100.0, 200.0, 0, 300.0}

Definition at line 132 of file LTC2662.h.

◆ LTC2662_MIN_OUTPUT

const float LTC2662_MIN_OUTPUT[10] = {0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0}

Definition at line 131 of file LTC2662.h.