GENERAL DESCRIPTION

The TC7116A/TC7117A are 3-1/2 digit CMOS analog to-digital converters (ADCs) containing all the active components necessary to construct a 0.05 resolution measurement system. Seven-segment decoders, polarity and digit drivers, voltage reference, and clock circuit are integrated on-chip. The TC7116A drives liquid crystal displays (LCDs) and includes a backplane driver. The TC7117A drives common anode light emitting diode (LED) displays directly with an 8-mA drive current per segment.

These devices incorporate a display hold (HLDR) function. The displayed reading remains indefinitely, as long as HLDR is held high. Conversions continue, but output data display latches are not updated. The reference low input (VREF – ) is not available as it is with the TC7106/7107. VREF – is tied internally to analog common in the TC7116A/7117A devices.

The TC7116A/7117A reduces linearity error to less than 1 count. Roll-over error (the difference in readings for equal magnitude but opposite polarity input signals) is below ±1 count. High-impedance differential inputs offer 1 pA leakage current and a 1012Ω input impedance. The 15 µVP-P noise performance guarantees a “rock solid” reading. The auto-zero cycle guarantees a zero display reading with a 0V input.

The TC7116A and TC7117A feature a precision, low drift internal reference, and are functionally identical to the TC7116/TC7117. A low-drift external reference is not normally required with the TC7116A/TC7117A.

FEATURES

■ Low Temperature Drift Internal Reference

TC7116/TC7117 ............................. 80 ppm/°C Typ

TC7116A/TC7117A ........................ 20 ppm/°C Typ

■ Display Hold Function

■ Directly Drives LCD or LED Display

■ Guaranteed Zero Reading With Zero Input

■ Low Noise for Stable

Display ......... 2V or 200 mV Full-Scale Range (FSR)

■ Auto-Zero Cycle Eliminates Need for Zero Adjustment Potentiometer

■ True Polarity Indication for Precision Null Applications

■ Convenient 9V Battery Operation (TC7116/TC7116A)

■ High Impedance CMOS Differential Inputs.... 1012Ω

■ Low Power Operation .................................... 10 mW