Linduino  1.3.0
Linear Technology Arduino-Compatible Demonstration Board

LTC2758: Dual Serial 18-Bit SoftSpan IOUT DAC. More...

Detailed Description

LTC2758: Dual Serial 18-Bit SoftSpan IOUT DAC.

The LTC2758 is a dual, current-output, serial-input precision multiplying DAC
with selectable output ranges. Ranges can either be programmed in software for
maximum flexibility (each of the DACs can be programmed to any one of six output
ranges) or hardwired through pin-strapping. Two unipolar ranges are available
(0V to 5V and 0V to 10V), and four bipolar ranges (±2.5V, ±5V, ±10V and –2.5V
to 7.5V). These ranges are obtained when an external precision 5V reference is
used. The output ranges for other reference voltages are easy to calculate by
observing that each range is a multiple of the external reference voltage. The
ranges can then be expressed: 0 to 1×, 0 to 2×, ±0.5×, ±1×, ±2×, and –0.5× to 1.5×.

The LTC2758 has 5 internal registers for each DAC, a total of 10 registers (see
Block Diagram). Each DAC channel has two sets of double-buffered registers, one
set for the code data, and one for the output range of the DAC, plus one readback
register.

SPI DATA FORMAT (MSB First):

                       Byte #1                         Byte #2                         Byte #3                         Byte #4
Data In (Write code):  C3  C2  C1  C0  A3  A2  A1  A0  D17 D16 D15 D14 D13 D12 D11 D10 D9  D8  D7  D6  D5  D4  D3  D2  D1  D0  X   X   X   X   X   X
Data In (Wrire Span):  C3  C2  C1  C0  A3  A2  A1  A0  X   X   X   X   X   X   X   X   X   X   X   X   S3  S2  S1  S0  X   X   X   X   X   X   X   X

Cx   : Command Code Bits
Ax   : Address Code Bits
Sx   : Span Select Bits
Dx   : Data Bits
X    : Don't care

Example Code:

  LTC2758_write(LTC2758_CS, LTC2758_WRITE_SPAN_DAC, DAC_SELECTED, span);
  data = LTC2758_voltage_to_code(voltage, DAC_RANGE_LOW, DAC_RANGE_HIGH);
  LTC2758_write(LTC2758_CS, LTC2758_WRITE_CODE_UPDATE_DAC, DAC_SELECTED, data);

http://www.linear.com/product/LTC2758

http://www.linear.com/product/LTC2758#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 LTC2758: Dual Serial 18-Bit SoftSpan IOUT DAC

Definition in file LTC2758.h.

Go to the source code of this file.

Functions

void LTC2758_write (uint8_t cs, uint8_t dac_command, uint8_t dac_address, uint32_t data)
 Transmits 32 bit input stream: 4-bit command + 4-bit don't-care + 18-bit data + 6 don't care. More...
 
float LTC2758_code_to_voltage (uint32_t dac_code, float min_output, float max_output)
 Calculate the LTC2758 DAC output voltage given the DAC code and and the minimum / maximum outputs for a given softspan range. More...
 
uint32_t LTC2758_voltage_to_code (float dac_voltage, float min_output, float max_output)
 Calculate a LTC2758 DAC code given the desired output voltage and the minimum / maximum outputs for a given softspan range. More...
 

Macros

#define LTC2758_CS   QUIKEVAL_CS
 Define the SPI CS pin. More...
 
LTC2758 DAC Addresses
#define ADDRESS_DACA   0x00
 
#define ADDRESS_DACB   0x02
 
#define ADDRESS_DAC_ALL   0x0E
 
LTC2758 Command Codes

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

#define LTC2758_WRITE_SPAN_DAC   0x20
 Write Span DAC n. More...
 
#define LTC2758_WRITE_CODE_DAC   0x30
 Write Code DAC n. More...
 
#define LTC2758_UPDATE_DAC   0x40
 Update DAC n. More...
 
#define LTC2758_UPDATE_ALL   0x50
 Update All DACs. More...
 
#define LTC2758_WRITE_SPAN_UPDATE_DAC   0x60
 Write Span DAC n and Update DAC n. More...
 
#define LTC2758_WRITE_CODE_UPDATE_DAC   0x70
 Write Code DAC n and Update DAC n. More...
 
#define LTC2758_WRITE_SPAN_UPDATE_ALL   0x80
 Write Span DAC n and Update All DACs. More...
 
#define LTC2758_WRITE_CODE_UPDATE_ALL   0x90
 Write Code DAC n and Update All DACs. More...
 
#define LTC2758_READ_INPUT_SPAN_REG   0xA0
 Read Input Span Register DAC n. More...
 
#define LTC2758_READ_INPUT_CODE_REG   0xB0
 Read Input Code Register DAC n. More...
 
#define LTC2758_READ_DAC_SPAN_REG   0xC0
 Read DAC Span Register DAC n. More...
 
#define LTC2758_READ_DAC_CODE_REG   0xD0
 Read DAC Code Register DAC n. More...
 
#define LTC2758_PREVIOUS_CMD   0xF0
 Set by previous command. More...
 

Function Documentation

◆ LTC2758_code_to_voltage()

float LTC2758_code_to_voltage ( uint32_t  dac_code,
float  min_output,
float  max_output 
)

Calculate the LTC2758 DAC output voltage given the DAC code and and the minimum / maximum outputs for a given softspan range.

Returns
Floating point voltage

Definition at line 89 of file LTC2758.cpp.

◆ LTC2758_voltage_to_code()

uint32_t LTC2758_voltage_to_code ( float  dac_voltage,
float  min_output,
float  max_output 
)

Calculate a LTC2758 DAC code given the desired output voltage and the minimum / maximum outputs for a given softspan range.

Returns
32 bit data

Definition at line 97 of file LTC2758.cpp.

◆ LTC2758_write()

void LTC2758_write ( uint8_t  cs,
uint8_t  dac_command,
uint8_t  dac_address,
uint32_t  data 
)

Transmits 32 bit input stream: 4-bit command + 4-bit don't-care + 18-bit data + 6 don't care.

Returns
void

Definition at line 77 of file LTC2758.cpp.

Macro Definition Documentation

◆ ADDRESS_DAC_ALL

#define ADDRESS_DAC_ALL   0x0E

Definition at line 96 of file LTC2758.h.

◆ ADDRESS_DACA

#define ADDRESS_DACA   0x00

Definition at line 94 of file LTC2758.h.

◆ ADDRESS_DACB

#define ADDRESS_DACB   0x02

Definition at line 95 of file LTC2758.h.

◆ LTC2758_CS

#define LTC2758_CS   QUIKEVAL_CS

Define the SPI CS pin.

Definition at line 90 of file LTC2758.h.

◆ LTC2758_PREVIOUS_CMD

#define LTC2758_PREVIOUS_CMD   0xF0

Set by previous command.

Definition at line 114 of file LTC2758.h.

◆ LTC2758_READ_DAC_CODE_REG

#define LTC2758_READ_DAC_CODE_REG   0xD0

Read DAC Code Register DAC n.

Definition at line 113 of file LTC2758.h.

◆ LTC2758_READ_DAC_SPAN_REG

#define LTC2758_READ_DAC_SPAN_REG   0xC0

Read DAC Span Register DAC n.

Definition at line 112 of file LTC2758.h.

◆ LTC2758_READ_INPUT_CODE_REG

#define LTC2758_READ_INPUT_CODE_REG   0xB0

Read Input Code Register DAC n.

Definition at line 111 of file LTC2758.h.

◆ LTC2758_READ_INPUT_SPAN_REG

#define LTC2758_READ_INPUT_SPAN_REG   0xA0

Read Input Span Register DAC n.

Definition at line 110 of file LTC2758.h.

◆ LTC2758_UPDATE_ALL

#define LTC2758_UPDATE_ALL   0x50

Update All DACs.

Definition at line 104 of file LTC2758.h.

◆ LTC2758_UPDATE_DAC

#define LTC2758_UPDATE_DAC   0x40

Update DAC n.

Definition at line 103 of file LTC2758.h.

◆ LTC2758_WRITE_CODE_DAC

#define LTC2758_WRITE_CODE_DAC   0x30

Write Code DAC n.

Definition at line 102 of file LTC2758.h.

◆ LTC2758_WRITE_CODE_UPDATE_ALL

#define LTC2758_WRITE_CODE_UPDATE_ALL   0x90

Write Code DAC n and Update All DACs.

Definition at line 109 of file LTC2758.h.

◆ LTC2758_WRITE_CODE_UPDATE_DAC

#define LTC2758_WRITE_CODE_UPDATE_DAC   0x70

Write Code DAC n and Update DAC n.

Definition at line 106 of file LTC2758.h.

◆ LTC2758_WRITE_SPAN_DAC

#define LTC2758_WRITE_SPAN_DAC   0x20

Write Span DAC n.

Definition at line 101 of file LTC2758.h.

◆ LTC2758_WRITE_SPAN_UPDATE_ALL

#define LTC2758_WRITE_SPAN_UPDATE_ALL   0x80

Write Span DAC n and Update All DACs.

Definition at line 108 of file LTC2758.h.

◆ LTC2758_WRITE_SPAN_UPDATE_DAC

#define LTC2758_WRITE_SPAN_UPDATE_DAC   0x60

Write Span DAC n and Update DAC n.

Definition at line 105 of file LTC2758.h.