LTC2492: 24-Bit, 4-Channel Delta Sigma ADCs with Easy Drive Input Current Cancellation.
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LTC2492: 24-Bit, 4-Channel Delta Sigma ADCs with Easy Drive Input Current Cancellation.
The LTC2492 is a 4-channel (2-differential) 24-bit No Latency Delta Sigma
TM ADC with Easy Drive technology. The patented sampling scheme eliminates
dynamic input current errors and the shortcomings of on-chip buffering
through automatic cancellation of differential input current. This allows
large external source impedances, and rail-to-rail input signals to be
directly digitized while maintaining exceptional DC accuracy.
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 : 1 0 EN SGL OS A2 A1 A0 EN2 IM FA FB SPD 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
*Dx : Data Bits Below lsb
EN : Enable Bit (0-keep previous mode, 1-change mode)
SGL : Enable Single-Ended Bit (0-differential, 1-single-ended)
OS : ODD/Sign Bit
Ax : Address Select Bit
IM : Internal Temperature Sensor Bit(0-ADC , 1-Temperature Sensor)
Fx : Frequency Rejection Bits
SPD : Speed Mode Bit (0-1x, 1-2x)
FIMSPD : Double Output Rate Select Bit (0-Normal rate, auto-calibration on, 2x rate, auto_calibration off)
Command Byte #1
1 0 EN SGL OS S2 S1 S0 Comments
1 0 0 X X X X X Keep Previous Mode
1 0 1 0 X X X X Differential Mode
1 0 1 1 X X X X Single-Ended Mode
Example Code:
Read Channel 0 in Single-Ended
uint16_t miso_timeout = 1000;
adc_command = LTC2492_CH0 | LTC2492_OSR_32768 | LTC2492_SPEED_2X; // Build ADC command for channel 0
// OSR = 32768*2 = 65536
if(LTC2492_EOC_timeout(LTC2492_CS, miso_timeout)) // Check for EOC
return; // Exit if timeout is reached
LTC2492_read(LTC2492_CS, adc_command, &adc_code); // Throws out last reading
if(LTC2492_EOC_timeout(LTC2492_CS, miso_timeout)) // Check for EOC
return; // Exit if timeout is reached
LTC2492_read(LTC2492_CS, adc_command, &adc_code); // Obtains the current reading and stores to adc_code variable
// Convert adc_code to voltage
adc_voltage = LTC2492_code_to_voltage(adc_code, LTC2492_lsb, LTC2492_offset_code);
http://www.linear.com/product/LTC2492
http://www.linear.com/product/LTC2492#demoboards
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Header for LTC2492: 24-Bit, 4-Channel Delta Sigma ADCs with Selectable Speed/Resolution
Definition in file LTC2492.h.