The TC7129 is a 4-1/2-digit analog-to-digital converter (ADC) from Microchip that directly drives a multiplexed liquid crystal display (LCD). It is fabricated in high-performance, low-power CMOS and is specifically designed 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 10µV 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. Over range and under range 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 capture a reading in the event of an overvoltage or undervoltage.
The TC7129 is a 4‑1/2‑digit ADC that directly drives multiplexed LCD displays for multimeter and digital measurement applications. It integrates a true differential input, low‑power operation (500 µA at 9 V), over‑range/under‑range outputs, a low‑battery indicator and continuity detection, making it suitable for battery‑powered instruments.
Key electrical characteristics include a count resolution of +19,999, a supply voltage range of 6‑12 V, a clock frequency of 120 kHz, high common‑mode rejection (110 dB), and dedicated pin functions for LCD segment control, range selection and status signals. The device is offered in 40‑pin PDIP, 44‑pin QFP and 44‑pin PLCC packages.
| Count Resolution | +19,999 |
|---|---|
| Low Power Consumption | 500 µA at 9 V |
| High Common Mode Rejection Ratio | 110 dB |
| Supply Voltage Range | 6 V to 12 V |
| Clock Frequency | 120 kHz |
| Common Voltage | 2.8 V to 3.5 V |
| Digital Ground Voltage | 4.5 V to 5.8 V |
| Low Battery Flag Activation | 6.3 V to 7.2 V |
The TC7129 provides a count resolution of +19,999.
It consumes 500 µA at a 9 V supply.
The device operates with a clock frequency of 120 kHz.
The TC7129 works with supply voltages from 6 V to 12 V.