GENERAL DESCRIPTION
The ALD500RAU/ALD500RA/ALD500R are integrating dual slope analog processors, designed to operate on ±5V power supplies for building precision analog-to-digital converters. The ALD500RAU/ALD500RA/ALD500R feature specifications suitable for 18 bit/17 bit/16 bit resolution conversion, respectively. Together with three capacitors, two resistors, and a digital controller, a precision Analog to Digital converter with auto zero can be implemented. The digital controller can be implemented by an external microcontroller, under either hardware (fixed logic) or software control. For ultra high resolution applications, up to 23 bit conversion can be implemented with an appropriate digital controller and software.

FEATURES
• Resolution up to 18 bits plus sign bit and over-range bit
• Accuracy independent of input source impedances
• Accurate on-chip voltage reference
• Tempco as low as 10 ppm/°C guaranteed
• Chip select - power down mode
• High input impedance of 1012 Ω
• Inherently filters and integrates any external noise spikes
• Differential analog input
• Wide bipolar analog input voltage range ±3.5V
• Automatic zero offset compensation
• Low linearity error - as low as 0.001% typical
• Fast zero-crossing comparator - 1µs
• Low power dissipation - 6mW typical
• Automatic internal polarity detection
• Low input current - 2pA typical
• Optional digital control from a microcontroller, an ASIC, or a dedicated digital circuit
• Flexible conversion speed vs. resolution trade-off

APPLICATIONS
• 4 1/2 digits to 5 1/2 digits plus sign measurements
• Precision analog signal processor
• Precision sensor interface
• High accuracy DC measurement functions
• Portable battery operated instruments
• Computer peripheral
• PCMCIA

BENEFITS
• Low cost, simple functionality
• Wide dynamic signal range
• Very high noise immunity
• Automatic compensation and cancellation of error sources
• Easy to use to acquire bipolar signals
• Up to 19 bit (18 bit + sign bit) single conversion or 21 bit (20 bit + sign bit) multiple conversion and noise performance
• Inherently linear and stable with temperature and component variations