Description

The AD7820 is a high speed, microprocessor-compatible 8-bit ADC which uses a half-flash conversion technique to achieve a conversion time of 1.36 µs. The converter has a 0 V to +5 V analog input voltage range with a single +5 V supply.The half-flash technique consists of 31 comparators, a most significant 4-bit ADC and a least significant 4-bit ADC. The input to the AD7820 is tracked and held by the input sampling circuitry, eliminating the need for an external sample-and-hold for signals with slew rates less than 100 mV/µs.The part is designed for ease of microprocessor interface with the AD7820 appearing as a memory location or I/O port without the need for external interfacing logic. All digital outputs use latched, three-state output buffer circuitry to allow direct connection to a microprocessor data bus or system input port. A non-three state overflow output is also provided to allow cascading of devices to give higher resolution.