GENERAL DESCRIPTION

The TC7129 is a 4-1/2 digit analog-to-digital converter (ADC) that directly drives a multiplexed liquid crystal display (LCD). Fabricated in high-performance, low-power CMOS, the TC7129 ADC is designed specifically for high resolution, battery-powered digital multimeter applications. The traditional dual-slope method of A/D conversion has been enhanced with a successive integration technique to produce readings accurate to better than 0.005 of full scale, and resolution down to 10 µV per count.

The TC7129 includes features important to multimeter applications. It detects and indicates low-battery condition. A continuity output drives an annunciator on the display, and can be used with an external driver to sound an audible alarm. Overrange and underrange outputs and a range change input provide the ability to create auto-ranging instruments. For snapshot readings, the TC7129 includes a latch-and-hold input to freeze the present reading. This combination of features makes the TC7129 the ideal choice for full-featured multimeter and digital measurement applications.

FEATURES

■ Count Resolution ......................................... ±19,999

■ Resolution on 200 mV Scale .......................... 10 µV

■ True Differential Input and Reference

■ Low Power Consumption ...................500 µA at 9V

■ Direct LCD Driver for 4-1/2 Digits, Decimal Points, Low-Battery Indicator, and Continuity Indicator

■ Overrange and Underrange Outputs

■ Range Select Input ............................................ 10:1

■ High Common-Mode Rejection Ratio ......... 110 dB

■ External Phase Compensation Not Required