Dual 24-Bit, Low-Power, High-SNR, 4ksps Delta-Sigma ADCs with Integrated PGAs

The MAX11284 is a dual 24-bit delta sigma ADC that achieves excellent SNR while dissipating a low 3.6mW per ADC. Precision DC and AC measurements can be made at sample rates up to 4ksps. Integral nonlinearity is guaranteed to 4ppm maximum and the THD is -120dB. The MAX11284 communicates through an SPI-compatible serial interface and is available in a small, 40-pin TQFN package.

The PGAs can operate in either low-noise (9.1nV/√Hz) or low-power (13.6nV/√Hz) mode, and have selectable gain values ranging from 1x to 128x. Optional buffers are also included to provide isolation of the signal inputs from the switched capacitor sampling network. This allows the ADCs to be used with high-impedance sources without compromising available dynamic range.

The MAX11284 operates from a single 2.7V to 3.6V analog supply, or split ±1.8V analog supplies, allowing the analog input to be sampled below ground. The digital supply range is 2.0V to 3.6V, allowing communication with 2.5V, 3V, or 3.3V logic.

Applications

* ATE * High-Precision Portable Sensors * Medical Equipment * Scientific Instrumentation * Seismic Data Acquisition

* High Resolution for Instrumentation Applications That Require a Wide Dynamic Range * 131dB SNR at 31.25sps in Buffer Mode

* 114dB SNR at 2000sps in Buffer Mode

* Low Power * Digital Current with FIR Filter, 1ksps: 500μA

* Analog Current PGA Low-Power Mode: 2.1mA

* Sleep Current: 1.2μA

* High Accuracy for DC Measurements

* 1ppm INL (typ), 4ppm (max)

* Single/Split Analog Supplies Provide Input Voltage Range Flexibility

* 2.7V to 3.6V (Single-Supply) or ±1.8V (Split Supplies)

* Digital Filters

* Programmable SINC + FIR + IIR

* Linear/Minimum Phase Response

* Programmable High-Pass Filter

* Selectable FIR Data Rates: 31.25sps to 4ksps

* Enables System Integration

* Low-Noise and Low-Power mode PGA with Gains of 1, 2, 4, 8, 16, 32, 64, 128

* Signal Buffer Optional

* 2 General-Purpose I/Os

* Integrated Offset and Gain Self-Calibration and System Gain and Offset Calibration Registers

* Small 40-Pin TQFN Package