32-Bit Over-Sampling ADC with Configurable Digital Filter

The LTC2508-32 is a low noise, low power, high-performance 32-bit ADC with an integrated configurable digital filter. Operating from a single 2.5V supply, the LTC2508-32 features a fully differential input range up to ±VREF , with VREF ranging from 2.5V to 5.1V. The LTC2508-32 supports a wide common mode range from 0V to VREF simplifying analog signal conditioning requirements.

The LTC2508-32 simultaneously provides two output codes: (1) a 32-bit digitally filtered high precision low noise code, and (2) a 22-bit no latency composite code. The configurable digital filter reduces measurement noise by lowpass filtering and down-sampling the stream of data from the SAR ADC core, giving the 32-bit filtered output code. The 22-bit composite code consists of a 14-bit code representing the differential voltage and an 8-bit code representing the common mode voltage. The 22-bit composite code is available each conversion cycle, with no cycle of latency.

The digital filter can be easily configured for 4 different down-sampling factors by pin strapping. The configurations provide a dynamic range of 131dB at 3.9ksps and 145dB at 61sps. The digital lowpass filter relaxes the requirements for analog anti-aliasing. Multiple LTC2508-32 devices can be easily synchronized using the SYNC pin.

Applications

* Seismology

* Energy Exploration

* Automated Test Equipment (ATE)

* High-Accuracy Instrumentation

* ±0.5ppm INL (Typ)* 145dB Dynamic Range (Typ) at 61sps* 131dB Dynamic Range (Typ) at 4ksps* Guaranteed 32-Bits No Missing Codes* Configurable Digital Filter with Synchronization

* Relaxed Anti-Aliasing Filter Requirements

* Dual Output 32-Bit SAR ADC

* 32-Bit Digitally Filtered Low Noise Output* 14-Bit Differential + 8-Bit Common Mode 1Msps No Latency Output

* Wide Input Common-Mode Range* Guaranteed Operation to 85°C* 1.8V to 5V SPI-Compatible Serial I/O* Low Power: 24mW at 1Msps* 24-Lead 7mm × 4mm DFN Package