8.1 Overview

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. Functional Block Diagram shows a block diagram for the ADS1291, ADS1292, and ADS1292R.