Texas Instruments ADS7028 and ADS7138 analog-to-digital converters

Texas Instruments’ ADS7028 and ADS7138 analog-to-digital converters (ADCs) feature eight channels that can be configured in any combination of analog inputs, digital inputs or digital outputs. The multiplexed, successive approximation register (SAR) ADCs provide good performance for applications such as rack servers, AC drive power stage modules, automotive centre information displays and mobile robot CPU boards.

The 12-bit ADCs feature open-drain, push-pull digital outputs for I/O expansion, while the devices’ analog watchdog function includes an event counter for transient rejection and programmable thresholds for each channel. They have wide operating ranges of 2.35 to 5.5 V AVDD and 1.65 to 5.5 V DVDD. They also have an internal oscillator for ADC processes, as well as a built-in cyclical redundancy check for power-up configuration and data read/write operations.

The ADS7028 communicates through an SPI-compatible interface with a sampling frequency of 1 MSPS, while the ADS7138 communicates using an I²C-compatible interface capable of operating at a frequency of up to 3.4 MHz. Both ADCs operate in either autonomous or single-shot conversion mode. The ADS7028 ADC also offers a root-mean-square module that computes a 16-bit true RMS output for any analog input, as well as a zero-crossing-detect module that features built-in transient rejection and hysteresis near configurable threshold crossings.