The CDP68HC68A2 is a CMOS 8-bit or 10-bit successive approximation analog to digital converter (A/D) with a standard Serial Peripheral Interface (SPI) bus and eight multiplexed analog inputs. Voltage referencing is user selectable to be relative to either VDD or analog channel 0 (AI0). The analog inputs can range between VSS and VDD.
The CDP68HC68A2 employs a switched capacitor, successive approximation A/D conversion technique which provides an inherent sample-and-hold function. An onchip Schmitt oscillator provides the internal timing for the A/D converter. The Schmitt input can be externally clocked or connected to a single, external capacitor to form an RC oscillator with a period of approximately 10-30ns per picofarad.
Conversion times are proportional to the oscillator period. At the maximum specified frequency of 1MHz, 10-bit conversions take 14μs per channel. At the same frequency, 8-bit conversions consume 12μs per channel.

Features
• 10-Bit Resolution
• 8-Bit Mode for Single Data Byte Transfers
• SPI (Serial Peripheral Interface) Compatible
• Operates Ratiometrically Referencing VDD or an External Source
• 14μs 0-Bit Conversion Time
• 8 Multiplexed Analog Input Channels
• Independent Channel Select
• Three Modes of Operation
• On Chip Oscillator
• Low Power CMOS Circuitry
• Intrinsic Sample and Hold