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Linduino
1.3.0
Linear Technology Arduino-Compatible Demonstration Board
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LTC2440: 24-Bit, Differential Delta Sigma ADCs with Selectable Speed/Resolution. More...
LTC2440: 24-Bit, Differential Delta Sigma ADCs with Selectable Speed/Resolution.
The LTC2440 is a high speed 24-bit No Latency Delta Sigma TM ADC with 5ppm INL and 5uV offset. It uses proprietary delta-sigma architecture enabling variable speed and resolution with no latency. Ten speed/resolution combinations (6.9Hz/200nVRMS to 3.5kHz/25uVRMS) are programmed through a simple serial interface. Alternatively, by tying a single pin HIGH or LOW, a fast (880Hz/2uVRMS) or ultralow noise (6.9Hz, 200nVRMS, 50/60Hz rejection) speed/resolution combination can be easily selected. The accuracy (offset, full-scale, linearity, drift) and power dissipation are independent of the speed selected. Since there is no latency, a speed/resolution change may be made between conversions with no degradation in performance. SPI DATA FORMAT (MSB First): Byte #1 Byte #2 Data Out : !EOC DMY SIG D28 D27 D26 D25 D24 D23 D22 D21 D20 D19 D18 D17 D16 Data In : OSR4 OSR3 OSR2 OSR1 OSR1 X X X X X X X X X X X Byte #3 Byte #4 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 *D3 *D2 *D1 *D0 X X X X X X X X X X X X X X X X !EOC : End of Conversion Bit (Active Low) DMY : Dummy Bit (Always 0) SIG : Sign Bit (1-data positive, 0-data negative) Dx : Data Bits EN : Enable Bit (0-keep previous mode, 1-change mode) SGL : Enable Single-Ended Bit (0-differential, 1-single-ended) Sx : Address Select Bit 0SRX : Over Sampling Rate Bits | CONVERSION RATE | | INTERNAL | EXTERNAL | OSR4 OSR3 OSR2 OSR1 OSR1 | 9MHz CLOCK | 10.24MHz CLOCK | RMS NOISE | ENOB | OSR x 0 0 0 1 3.52kHz 4kHz 23uV 17 64 x 0 0 1 0 1.76kHz 2kHz 3.5uV 20 128 0 0 0 0 0 880Hz 1kHz 2uV 21.3 256* x 0 0 1 1 880Hz 1kHz 2uV 21.3 256 x 0 1 0 0 440Hz 500Hz 1.4uV 21.8 512 x 0 1 0 1 220Hz 250Hz 1uV 22.4 1024 x 0 1 1 0 110Hz 125Hz 750nV 22.9 2048 x 0 1 1 1 55Hz 62.5Hz 510nV 23.4 4096 x 1 0 0 0 27.5Hz 31.25Hz 375nV 24 8192 X 1 0 0 1 13.75Hz 15.625Hz 250nV 24.4 16384 X 1 1 1 1 6.87kHz 7.8125Hz 200nV 24.6 32768** ** Address allows tying SDI HIGH *Additional address to allow tying SDI LOW Example Code: Read ADC with OSR of 65536 uint16_t miso_timeout = 1000; if(!LTC2440_EOC_timeout(LTC2440_CS, miso_timeout)) // Check for EOC LTC2440_read(LTC2440_CS, adc_command, &adc_code); // Throws out reading else { return; } if(!LTC2440_EOC_timeout(LTC2440_CS, miso_timeout)) // Check for EOC LTC2440_read(LTC2440_CS, adc_command, &adc_code); // Take valid reading else { return; } // Convert adc_code to voltage adc_voltage = LTC2440_code_to_voltage(adc_code, LTC2440_vref);
http://www.linear.com/product/LTC2440
http://www.linear.com/product/LTC2440#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:
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 LTC2440: 24-Bit, Differential Delta Sigma ADCs with Selectable Speed/Resolution.
Definition in file LTC2440.h.
Go to the source code of this file.
Functions | |
int8_t | LTC2440_EOC_timeout (uint8_t cs, uint16_t miso_timeout) |
Checks for EOC with a specified timeout. More... | |
void | LTC2440_read (uint8_t cs, uint8_t adc_command, int32_t *adc_code) |
Reads from LTC2440. More... | |
float | LTC2440_code_to_voltage (int32_t adc_code, float vref) |
Calculates the voltage corresponding to an adc code, given the reference (in volts) More... | |
Macros | |
#define | LTC2440_CS QUIKEVAL_CS |
Define the SPI CS pin. More... | |
Oversample Ratio (OSR) Commands | |
#define | LTC2440_OSR_64 0x08 |
#define | LTC2440_OSR_128 0x10 |
#define | LTC2440_OSR_256_ 0x00 |
#define | LTC2440_OSR_256 0x18 |
#define | LTC2440_OSR_512 0x20 |
#define | LTC2440_OSR_1024 0x28 |
#define | LTC2440_OSR_2048 0x30 |
#define | LTC2440_OSR_4096 0x38 |
#define | LTC2440_OSR_8192 0x40 |
#define | LTC2440_OSR_16384 0x48 |
#define | LTC2440_OSR_32768 0x78 |
float LTC2440_code_to_voltage | ( | int32_t | adc_code, |
float | vref | ||
) |
Calculates the voltage corresponding to an adc code, given the reference (in volts)
adc_code | Code read from adc |
vref | VRef (in volts) |
Definition at line 92 of file LTC2440.cpp.
int8_t LTC2440_EOC_timeout | ( | uint8_t | cs, |
uint16_t | miso_timeout | ||
) |
Checks for EOC with a specified timeout.
cs | Chip Select pin |
miso_timeout | Timeout (in milliseconds) |
Definition at line 80 of file LTC2440.cpp.
void LTC2440_read | ( | uint8_t | cs, |
uint8_t | adc_command, | ||
int32_t * | adc_code | ||
) |
Reads from LTC2440.
cs | Chip select |
adc_command | 1 byte command written to LTC2440 |
adc_code | 4 byte conversion code read from LTC2440 |
Definition at line 86 of file LTC2440.cpp.
#define LTC2440_CS QUIKEVAL_CS |