GENERAL DESCRIPTION
The AD7811 and AD7812 are high speed, low power, 10-bit A/D converters that operate from a single +2.7 V to +5.5 V supply. The devices contain a 2.3 µs successive approximation A/D converter, an on-chip track/hold amplifier, a 2.5 V on-chip reference and a high speed serial interface that is compatible with the serial interfaces of most DSPs (Digital Signal Processors) and microcontrollers. The user also has the option of using an external reference by connecting it to the VREF pin and setting the EXTREF bit in the control register. The VREF pin may be tied to VDD. At slower throughput rates the power-down mode may be used to automatically power down between conversions.

FEATURES
   10-Bit ADC with 2.3 ms Conversion Time
   The AD7811 has Four Single-Ended Inputs that
      Can Be Configured as Three Pseudo Differential
      Inputs with Respect to a Common, or as Two
      Independent Pseudo Differential Channels
   The AD7812 has Eight Single-Ended Inputs that Can
      Be Configured as Seven Pseudo Differential Inputs
      with Respect to a Common, or as Four Independent
      Pseudo Differential Channels
   Onboard Track and Hold
   Onboard Reference 2.5 V 6 2.5%
   Operating Supply Range: +2.7 V to +5.5 V
   Specifications at 2.7 V–3.6 V and 5 V 6 10%
   DSP-/Microcontroller-Compatible Serial Interface
   High Speed Sampling and Automatic Power-Down Modes
   Package Address Pin on the AD7811 and AD7812 Allows
      Sharing of the Serial Bus in Multipackage Applications
   Input Signal Range: 0 V to VREF
   Reference Input Range: 1.2 V to VDD