11-Bit Resolution Simultaneous Sampling ADC

The AD7861 is a multichannel simultaneous sampling A/D Converter (ADC) configured for the acquisition of voltage inputs in a motor control solution or three-phase power system.

The AD7861 combined with Analog Devices’ 16-bit fixed-point digital signal processor (DSP) provides a low cost 16-bit fixed-point microcontroller solution. The input stage has been designed to accommodate the types of signals frequently found in motor drives. The VIN1, VIN2, and VIN3 channels are simultaneously sampled inputs suitable for stator current acquisition. The AUX0–AUX3 channels are multiplexed and are suitable for slower moving inputs such as temperature and bus voltage of the diode rectifier output in a motor control application.

APPLICATIONS

* Motor Control

* 3-Phase Power Measurement

* Cellular Phones

* Data Acquisition

PRODUCT HIGHLIGHTS

* Simultaneous Sampling of Four Inputs

Four channel sample and hold amplifier (SHA) allows out of phase input signals to be sampled simultaneously, preserving the relative phase information. Sample-and-hold acquisition time is 1.6 µs and conversion time per channel is 3.2 µs (using a 12.5 MHz system clock).

* Flexible Analog Channel Sequencing

AD7861 supports acquisition of 2, 3 or 4 channels per group. Converted channel results are stored in registers and the data can be read in any order. The sampling and conversion time for two channels is 8 µs, three channels is 11.2 µs, and four channels is 14.4 µs (using a 12.5 MHz system clock).

* Single 5 V dc Operation

Low power, digital process.

* 11-Bit Resolution Analog-to-Digital Converter

* Seven Single-Ended Analog Inputs

Four Input Channels Simultaneously Sampled

Expansion with 4 Multiplexed Inputs

* Internal 2.5 V Reference