Low-Noise, 4 1/2 Digit, Single-Chip ADC with Multiplexed LCD Drivers

 

Part Number	Replacement	Explanation

Description

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The Maxim ICL7129A/MAX7129 is a high precision monolithic 4-1/2 digit A/D converter that directly drives a multiplexed liquid crystal display. Using a novel "successive integration" technique, the ICL7129A/MAX7129 has a ±20,000 count resolution on both 2.00000V and 200.00mV ranges. It features high impedance differential inputs, excellent differential linearity, true ratiometric operation and auto polarity. The only external active component required to make precision DVM/DPMs is a reference. The overrange and underrange outputs and the 10:1 range changing input facilitate the design of autoranging systems. The ICL7129A/MAX7129 detects and flags a LOW BATTERY condition and also checks for continuity, giving a visual indication and a logic level output which can be used to generate an audible signal.

The MAX7129 has a fullscale accuracy of 0.0005%, resolution of 10µV, zero reading drift of 0.5µV/°C, an input bias of 10pA max, and a rollover error of less than 1 count. Maxim has reduced the noise of the ICL7129A to 3µV—significantly lower than the MAX7129.

ICL7129A, MAX7129: Typical Operating Circuit Enlarge+

Key Features

• ±19,999 Count Resolution
• 10pA Max Input Bias Current (MAX7129)
• 3µV Peak-to-Peak Noise (ICL7129A)
• Onboard Multiplexed LCD Display Driver 4-1/2 Digits, 4 Decimal Points, 3 Annunciators
• Instant Continuity Detector
• Low Battery Detector and Indicator
• Overrange/Underrange Outputs
• Precise 10:1 Range Select
• 10µV Resolution
• Significantly Improved ESD Protection
• Monolithic, Low Power CMOS Design
• Eliminates Need for Compensation Capacitor