ADS1291_14 Datasheet, PDF (16/75 Pages) Texas Instruments – Power, 2-Channel, 24-Bit Analog Front-End for Biopotential Measurements

ADS1291
ADS1292
ADS1292R
SBAS502B – DECEMBER 2011 – REVISED SEPTEMBER 2012
OVERVIEW
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The ADS1291, ADS1292, and ADS1292R are low-power, multichannel, simultaneously-sampling, 24-bit delta-
sigma (ΔΣ) analog-to-digital converters (ADCs) with integrated programmable gain amplifiers (PGAs). These
devices integrate various electrocardiogram (ECG)-specific functions that make them well-suited for scalable
ECG, sports, and fitness applications. The devices can also be used in high-performance, multichannel data
acquisition systems by powering down the ECG-specific circuitry.
The ADS1291, ADS1292, and ADS1292R have a highly programmable multiplexer that allows for temperature,
supply, input short, and RLD measurements. Additionally, the multiplexer allows any of the input electrodes to be
programmed as the patient reference drive. The PGA gain can be chosen from one of seven settings (1, 2, 3, 4,
6, 8, and 12). The ADCs in the device offer data rates from 125 SPS to 8 kSPS. Communication to the device is
accomplished using an SPI-compatible interface. The device provides two general-purpose I/O (GPIO) pins for
general use. Multiple devices can be synchronized using the START pin.
The internal reference can be programmed to either 2.42 V or 4.033 V. The internal oscillator generates a 512-
kHz clock. The versatile right leg drive (RLD) block allows the user to choose the average of any combination of
electrodes to generate the patient drive signal. Lead-off detection can be accomplished either by using an
external pull-up or pull-down resistor or the device internal current source or sink. An internal ac lead-off
detection feature is also available. Apart from the above features, the ADS1292R provides options for internal
respiration circuitry. Figure 18 shows a block diagram for the ADS1291, ADS1292, and ADS1292R.
AVDD
VCAP1
PGA1P PGA1N VREFP VCAP2 VREFN
DVDD
Power-Supply Signal
Temperature Sensor Input
Test Signal
Lead-Off Excitation Source
IN1P
IN1N
IN2P
IN2N
RESP_MODP/
IN3P
RESP_MODN/
IN3N
EMI
Filter
EMI
Filter
PGA1
MUX
PGA2
(AVDD + AVSS)/2
RESP_EN
RESP
DEMOD1
(ADS1292R)
Reference
DS
ADC1
SPI
Control
Oscillator
DS
ADC2
RESP
DRDY
CS
SCLK
DIN
DOUT
CLKSEL
CLK
GPIO1/
RCLK
GPIO2/
RCLK
PWDN/
RESET
START
Resp Mod
(ADS1292R)
RLD
Amplifier
AVSS
RLDIN/
RLDREF
RLD
RLD
OUT
INV
PGA2N PGA2P
Figure 18. Functional Block Diagram
DGND
16
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