Linduino  1.3.0
Linear Technology Arduino-Compatible Demonstration Board

LTC2422: 1-/2-Channel 20-Bit uPower No Latency Delta-Sigma ADC in MSOP-10. More...

Detailed Description

LTC2422: 1-/2-Channel 20-Bit uPower No Latency Delta-Sigma ADC in MSOP-10.

The LTC2421/LTC2422 are 1- and 2-channel 2.7V to 5.5V micropower 20-bit analog-
to-digital converters with an integrated oscillator, 8ppm INL and 1.2ppm RMS
noise. These ultrasmall devices use delta-sigma technology and a new digital
filter architecture that settles in a single cycle. This eliminates the latency
found in conventional delta-sigma converters and simplifies multiplexed
applications. Through a single pin, the LTC2421/LTC2422 can be configured for
better than 110dB rejection at 50Hz or 60Hz +/-2%, or can be driven by an
external oscillator for a user defined rejection frequency in the range 1Hz to
120Hz. The internal oscillator requires no external frequency setting
components.

SPI DATA FORMAT (MSB First):

            Byte #1                            Byte #2

Data Out :  !EOC CH SIG EXR D19 D18 D17 D16   D15  D14  D13  D12  D11  D10 D9  D8
Data In  :  X    X   X   X   X   X   X   X     X    X    X    X    X    X   X   X

Byte #3
D7 D6 D5 D4 D3 D2 D1 D0
X  X  X  X  X  X  X  X

!EOC : End of Conversion Bit (Active Low)
CH   : Channel Indicator Bit (0 - CH0 , 1 - CH1)
SIG  : Sign Bit (1-data positive, 0-data negative)
EXR  : Extebded Input Range Indicator Bit
Dx   : Data Bits

Example Code:

Read Channel 0.

    uint16_t miso_timeout = 1000;
    if(LTC2422_EOC_timeout(LTC2422_CS, miso_timeout))        // Check for EOC
        return; // Handle exception if timeout exceeded without EOC
    LTC2422_adc_read(LTC2422_CS, &adc_channel, &adc_code);  // Read ADC

    if(adc_channel != 0)
    {
        if(LTC2422_EOC_timeout(LTC2422_CS, miso_timeout))    // Check for EOC
            return; // Handle exception if timeout exceeded without EOC
        LTC2422_adc_read(LTC2422_CS, &adc_channel, &adc_code); // Reads the ADC again if the first reading was not CH0
    }
    adc_voltage = LTC2422_code_to_voltage(adc_code, LTC2422_lsb);

http://www.linear.com/product/LTC2422

http://www.linear.com/product/LTC2422#demoboard

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.

Library Header File for LTC2422: 1-/2-Channel 20-Bit uPower No Latency Delta-Sigma ADC in MSOP-10

Definition in file LTC2422.h.

Go to the source code of this file.

Functions

uint8_t LTC2422_EOC_timeout (uint8_t cs, uint16_t miso_timeout)
 Checks for EOC with a specified timeout. More...
 
void LTC2422_adc_read (uint8_t cs, uint8_t *adc_channel, int32_t *code)
 Read ADC code from the LTC2422. More...
 
float LTC2422_code_to_voltage (int32_t adc_code, float LTC2422_lsb)
 Calculates the voltage given the ADC code and lsb weight. More...
 
void LTC2422_calculate_lsb (float LTC2422_reference_voltage, float *LTC2422_lsb)
 Calculates the lsb weight from the given reference voltage. More...
 

Macros

#define LTC2422_CS   QUIKEVAL_CS
 Define the SPI CS pin. More...
 

Variables

const float LTC2422_TYPICAL_lsb = 4.7683761E-6
 The LTC2422 typical least significant bit value with 5V full-scale. More...
 

Function Documentation

◆ LTC2422_adc_read()

void LTC2422_adc_read ( uint8_t  cs,
uint8_t *  adc_channel,
int32_t *  code 
)

Read ADC code from the LTC2422.

Does not wait for end-of-conversion. To automatically wait for conversion to complete, use the LTC2422_EOC_timeout before this function.

Returns
void
Parameters
csChip Select pin
adc_channelReturns channel number read.
codeReturns the ADC code read.

Definition at line 98 of file LTC2422.cpp.

◆ LTC2422_calculate_lsb()

void LTC2422_calculate_lsb ( float  LTC2422_reference_voltage,
float *  LTC2422_lsb 
)

Calculates the lsb weight from the given reference voltage.

Returns
Void
Parameters
LTC2422_reference_voltageMeasured reference voltage.
LTC2422_lsbOverwritten with the lsb weight in volts.

Definition at line 128 of file LTC2422.cpp.

◆ LTC2422_code_to_voltage()

float LTC2422_code_to_voltage ( int32_t  adc_code,
float  LTC2422_lsb 
)

Calculates the voltage given the ADC code and lsb weight.

Returns
calculated voltage (based on ADC code and lsb weight).
Parameters
adc_codeADC code read from LTC2422.
LTC2422_lsbLSB weight (determined by reference voltage).

Definition at line 119 of file LTC2422.cpp.

◆ LTC2422_EOC_timeout()

uint8_t LTC2422_EOC_timeout ( uint8_t  cs,
uint16_t  miso_timeout 
)

Checks for EOC with a specified timeout.

Returns
success or failure on timeout
Parameters
csChip Select pin
miso_timeoutTimeout (ms)

Definition at line 76 of file LTC2422.cpp.

Macro Definition Documentation

◆ LTC2422_CS

#define LTC2422_CS   QUIKEVAL_CS

Define the SPI CS pin.

Definition at line 104 of file LTC2422.h.

Variable Documentation

◆ LTC2422_TYPICAL_lsb

const float LTC2422_TYPICAL_lsb = 4.7683761E-6

The LTC2422 typical least significant bit value with 5V full-scale.

Definition at line 107 of file LTC2422.h.