Linduino  1.3.0
Linear Technology Arduino-Compatible Demonstration Board

LTC2636: Octal 12-/10-/8-Bit SPI VOUT DACs with 10ppm/°C Reference. More...

Detailed Description

LTC2636: Octal 12-/10-/8-Bit SPI VOUT DACs with 10ppm/°C Reference.

LTC2634: Quad 12-/10-/8-Bit Rail-to-Rail DACs with 10ppm/°C Reference.

The LTC2636 is a family of quad 16-/12-bit rail-to-rail DACs with integrated
10ppm/C maximum reference. The DACs have built-in high performance, rail-to-
rail, output buffers and are guaranteed monotonic. The LTC2636-L has a full-
scale output of 2.5V with the integrated reference and operates from a single
2.7V to 5.5V supply. The LTC2636-H has a full-scale output of 4.096V with the
integrated reference and operates from a 4.5V to 5.5V supply. Each DAC can also
operate with an external reference, which sets the full-scale output to 2 times
the external reference voltage. These DACs communicate via a SPI/MICROWIRE
compatible 4-wire serial interface which operates at clock rates up to 50MHz.
The LTC2636 incorporates a power-on reset circuit that is controlled by the
PORSEL pin. If PORSEL is tied to GND, the DACs reset to zero-scale. If PORSEL is
tied to VCC, the DACs reset to mid-scale.

SPI DATA FORMAT (MSB First):

24-Bit Load Sequence:

             Byte #1                   Byte #2                         Byte #3
             Command                   MSB                             LSB
LTC2636-12 : C3 C2 C1 C0 A3 A2 A1 A0   D11 D10 D9  D8  D7  D6  D5 D4   D3 D2 D1 D0 X  X  X  X
LTC2636-10 : C3 C2 C1 C0 A3 A2 A1 A0   D9  D8  D7  D6  D5  D4  D3 D2   D1 D0 X  X  X  X  X  X
LTC2636-8  : C3 C2 C1 C0 A3 A2 A1 A0   D7  D6  D5  D4  D3  D2  D1 D0   X  X  X  X  X  X  X  X


32-Bit Load Sequence:

             Byte #1                   Byte #2                   Byte #3                         Byte #4
             Command                   MSB                                                       LSB
LTC2636-12 : 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
LTC2636-10 : X  X  X  X  X  X  X  X    C3 C2 C1 C0 A3 A2 A1 A0   D9  D8  D7  D6  D5  D4  D3 D2   D1 D0 X  X  X  X  X  X
LTC2636-8  : X  X  X  X  X  X  X  X    C3 C2 C1 C0 A3 A2 A1 A0   D7  D6  D5  D4  D3  D2  D1 D0   X  X  X  X  X  X  X  X

Cx   : DAC Command Code
Ax   : DAC Address (0=DACA, 1=DACB, 2=DACC, 3=DACD, 4=DACE, 5=DACF, 6=DACG, 7=DACH, 0xFF=All DACs)
Dx   : DAC Data Bits
X    : Don't care


Example Code:

Set DAC A to 2V for 16-bit DAC.

    shift_count = 0;    // 16-bit DAC does not have to be shifted
    dac_voltage = 2.0;  // Sets dac voltage variable to 2v

    dac_code = LTC2636_voltage_to_code(dac_voltage, LTC2636_lsb, LTC2636_offset);       // Calculate DAC code from voltage, lsb, and offset
    LTC2636_write(LTC2636_CS, LTC2636_CMD_WRITE_UPDATE, LTC2636_DAC_A, dac_code << shift_count);    // Set DAC A with DAC code

http://www.linear.com/product/LTC2636

http://www.linear.com/product/LTC2634

http://www.linear.com/product/LTC2636#demoboards

http://www.linear.com/product/LTC2634#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.
  • Neither the name of Analog Devices, Inc. nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
  • 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.
  • Use of the software either in source or binary form, must be run on or directly connected to an Analog Devices Inc. component.

THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, INTELLECTUAL PROPERTY RIGHTS, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Header for LTC2636 Octal 12-/10-/8-Bit SPI VOUT DACs with 10ppm/°C Reference.

Definition in file LTC2636.h.

Go to the source code of this file.

Functions

void LTC2636_write (uint8_t cs, uint8_t dac_command, uint8_t dac_address, uint16_t dac_code)
 Write the 16-bit dac_code to the LTC2636. More...
 
uint16_t LTC2636_voltage_to_code (float dac_voltage, float LTC2636_lsb, int16_t LTC2636_offset)
 Calculate a LTC2636 DAC code given the desired output voltage, offset, and LSB value. More...
 
float LTC2636_code_to_voltage (uint16_t dac_code, float LTC2636_lsb, int16_t LTC2636_offset)
 Calculate the LTC2636 DAC output voltage given the DAC code, offset, and LSB value. More...
 
void LTC2636_calibrate (uint16_t dac_code1, uint16_t dac_code2, float voltage1, float voltage2, float *LTC2636_lsb, int16_t *LTC2636_offset)
 Calculate the LTC2636 offset and LSB voltages given two measured voltages and their corresponding codes. More...
 

Macros

#define LTC2636_CS   QUIKEVAL_CS
 Define the SPI CS pin. More...
 
LTC2636 Command Codes

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

#define LTC2636_CMD_WRITE   0x00
 Write to input register n. More...
 
#define LTC2636_CMD_UPDATE   0x10
 Update (power up) DAC register n. More...
 
#define LTC2636_CMD_WRITE_UPDATE_ALL   0x20
 Write to input register n, update (power up) all. More...
 
#define LTC2636_CMD_WRITE_UPDATE   0x30
 Write to input register n, update (power up) all. More...
 
#define LTC2636_CMD_POWER_DOWN   0x40
 Power down n. More...
 
#define LTC2636_CMD_POWER_DOWN_ALL   0x50
 Power down chip (all DACs and reference) More...
 
#define LTC2636_CMD_INTERNAL_REFERENCE   0x60
 Select internal reference (power up reference) More...
 
#define LTC2636_CMD_EXTERNAL_REFERENCE   0x70
 Select external reference (power down internal reference) More...
 
#define LTC2636_CMD_NO_OPERATION   0xF0
 No operation. More...
 
LTC2636 DAC addresses

Which DAC to operate on

#define LTC2636_DAC_A   0x00
 
#define LTC2636_DAC_B   0x01
 
#define LTC2636_DAC_C   0x02
 
#define LTC2636_DAC_D   0x03
 
#define LTC2636_DAC_E   0x04
 
#define LTC2636_DAC_F   0x05
 
#define LTC2636_DAC_G   0x06
 
#define LTC2636_DAC_H   0x07
 
#define LTC2636_DAC_ALL   0x0F
 

Function Documentation

◆ LTC2636_calibrate()

void LTC2636_calibrate ( uint16_t  dac_code1,
uint16_t  dac_code2,
float  voltage1,
float  voltage2,
float *  LTC2636_lsb,
int16_t *  LTC2636_offset 
)

Calculate the LTC2636 offset and LSB voltages given two measured voltages and their corresponding codes.

Returns
Void
Parameters
dac_code1First DAC code
dac_code2Second DAC code
voltage1First voltage
voltage2Second voltage
LTC2636_lsbReturns resulting LSB (volts)
LTC2636_offsetReturns resulting Offset (volts)

Definition at line 120 of file LTC2636.cpp.

◆ LTC2636_code_to_voltage()

float LTC2636_code_to_voltage ( uint16_t  dac_code,
float  LTC2636_lsb,
int16_t  LTC2636_offset 
)

Calculate the LTC2636 DAC output voltage given the DAC code, offset, and LSB value.

Returns
Calculated voltage
Parameters
dac_codeDAC code
LTC2636_lsbLSB value (volts)
LTC2636_offsetOffset (volts)

Definition at line 112 of file LTC2636.cpp.

◆ LTC2636_voltage_to_code()

uint16_t LTC2636_voltage_to_code ( float  dac_voltage,
float  LTC2636_lsb,
int16_t  LTC2636_offset 
)

Calculate a LTC2636 DAC code given the desired output voltage, offset, and LSB value.

Returns
The 16-bit code to send to the DAC
Parameters
dac_voltageVoltage to send to DAC
LTC2636_lsbLSB value (volts)
LTC2636_offsetOffset (volts)

Definition at line 99 of file LTC2636.cpp.

◆ LTC2636_write()

void LTC2636_write ( uint8_t  cs,
uint8_t  dac_command,
uint8_t  dac_address,
uint16_t  dac_code 
)

Write the 16-bit dac_code to the LTC2636.

Returns
Void
Parameters
csChip Select Pin
dac_commandCommand Nibble, left-justified, lower nibble set to zero
dac_addressDAC Address Nibble, right justified, upper nibble set to zero
dac_code16-bit DAC code

Definition at line 84 of file LTC2636.cpp.

Macro Definition Documentation

◆ LTC2636_CMD_EXTERNAL_REFERENCE

#define LTC2636_CMD_EXTERNAL_REFERENCE   0x70

Select external reference (power down internal reference)

Definition at line 125 of file LTC2636.h.

◆ LTC2636_CMD_INTERNAL_REFERENCE

#define LTC2636_CMD_INTERNAL_REFERENCE   0x60

Select internal reference (power up reference)

Definition at line 124 of file LTC2636.h.

◆ LTC2636_CMD_NO_OPERATION

#define LTC2636_CMD_NO_OPERATION   0xF0

No operation.

Definition at line 126 of file LTC2636.h.

◆ LTC2636_CMD_POWER_DOWN

#define LTC2636_CMD_POWER_DOWN   0x40

Power down n.

Definition at line 122 of file LTC2636.h.

◆ LTC2636_CMD_POWER_DOWN_ALL

#define LTC2636_CMD_POWER_DOWN_ALL   0x50

Power down chip (all DACs and reference)

Definition at line 123 of file LTC2636.h.

◆ LTC2636_CMD_UPDATE

#define LTC2636_CMD_UPDATE   0x10

Update (power up) DAC register n.

Definition at line 119 of file LTC2636.h.

◆ LTC2636_CMD_WRITE

#define LTC2636_CMD_WRITE   0x00

Write to input register n.

Definition at line 118 of file LTC2636.h.

◆ LTC2636_CMD_WRITE_UPDATE

#define LTC2636_CMD_WRITE_UPDATE   0x30

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

Definition at line 121 of file LTC2636.h.

◆ LTC2636_CMD_WRITE_UPDATE_ALL

#define LTC2636_CMD_WRITE_UPDATE_ALL   0x20

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

Definition at line 120 of file LTC2636.h.

◆ LTC2636_CS

#define LTC2636_CS   QUIKEVAL_CS

Define the SPI CS pin.

Definition at line 112 of file LTC2636.h.

◆ LTC2636_DAC_A

#define LTC2636_DAC_A   0x00

Definition at line 132 of file LTC2636.h.

◆ LTC2636_DAC_ALL

#define LTC2636_DAC_ALL   0x0F

Definition at line 140 of file LTC2636.h.

◆ LTC2636_DAC_B

#define LTC2636_DAC_B   0x01

Definition at line 133 of file LTC2636.h.

◆ LTC2636_DAC_C

#define LTC2636_DAC_C   0x02

Definition at line 134 of file LTC2636.h.

◆ LTC2636_DAC_D

#define LTC2636_DAC_D   0x03

Definition at line 135 of file LTC2636.h.

◆ LTC2636_DAC_E

#define LTC2636_DAC_E   0x04

Definition at line 136 of file LTC2636.h.

◆ LTC2636_DAC_F

#define LTC2636_DAC_F   0x05

Definition at line 137 of file LTC2636.h.

◆ LTC2636_DAC_G

#define LTC2636_DAC_G   0x06

Definition at line 138 of file LTC2636.h.

◆ LTC2636_DAC_H

#define LTC2636_DAC_H   0x07

Definition at line 139 of file LTC2636.h.