CMOS, Complete 12-bit, 100 H, Sampling ADC with ±10V Input Signal Range

The AD7870 / AD7875 / AD7876 is a fast, complete, 12-bit A/D converter. It consists of a track/hold amplifier, 8 µs successive approximation ADC, 3 V buried Zener reference and versatile interface logic. The ADC features a self-contained internal clock which is laser trimmed to guarantee accurate control of conversion time. No external clock timing components are required; the on-chip clock may he overridden by an external clock if required.

The parts offer a choice of three data output formats: a single, parallel, 12-bit word; two 8-bit bytes or serial data. Fast bus access times and standard control inputs ensure easy interfacing to modern microprocessors and digital signal processors.

All parts operate from ±5 V power supplies. The AD7870 and AD7876 accept input signal ranges of ±3 V and ±10 V, respectively, while the AD7875 accepts a unipolar 0 V to +5 V input range. The parts can convert full power signals up to 50 kHz.

The AD7870 / AD7875 / AD7876 feature dc accuracy specifications such as linearity, full-scale and offset error. In addition, the AD7870 and AD7875 are fully specified for dynamic performance parameters including distortion and signal-to-noise ratio.

The parts are available in a 24-pin, 0.3 inch-wide, plastic or hermetic dual-in-line package (DIP). The AD7870 and AD7875 are available in a 28-pin plastic leaded chip carrier (PLCC), while the AD7876 is available and in a 24-pin small outline (SOIC) package.

PRODUCT HIGHLIGHTS

* Complete 12-bit ADC on a chip.

The AD7870 / AD7875/ AD7876 provide all the functions necessary for analog-to-digital conversion and combine a 12-bit ADC with internal clock, track-and-hold amplifier and reference on a single chip.

* Dynamic specifications for DSP users.

The AD7870 and AD7875 are fully specified and tested for ac parameters, including signal-to-noise ratio, harmonic distortion and intermodulation distortion.

* Fast microprocessor interface.

Data access times of 57 ns make the parts compatible with modern 8-bit and 16-bit microprocessors and digital signal processors. Key digital timing parameters are tested and guaranteed over the full operating temperature range.

* Complete Monolithic 12-Bit ADC with:

2 µs Track/Hold Amplifier

8 µs A/D Converter

On-Chip Reference

Laser-Trimmed Clock

Parallel, Byte and Serial Digital Interface

* 57 ns Data Access Time