AD7825,pdf,datasheet

The AD7822/AD7825/AD7829 are high speed, 1-, 4-, and 8-channel, microprocessor-compatible, 8-bit analog-to-digital converters with a maximum throughput of 2 MSPS. The AD7822/ AD7825/AD7829 contain an on-chip reference of 2.5 V (2% tolerance); a track-and-hold amplifier; a 420 ns, 8-bit half-flash ADC; and a high speed parallel interface. The converters can operate from a single 3 V ± 10% and 5 V ± 10% supply.

The AD7822/AD7825/AD7829 combine the convert start and power-down functions at one pin, that is, the CONVST pin. This allows a unique automatic power-down at the end of a conversion to be implemented. The logic level on the CONVST pin is sampled after the end of a conversion when an EOC (end of conversion) signal goes high. If it is logic low at that point, the ADC is powered down. The AD7822 and AD7825 also have a separate power-down pin (see the Operating Modes section).

The parallel interface is designed to allow easy interfacing to microprocessors and DSPs. Using only address decoding logic, the parts are easily mapped into the microprocessor address space. The EOC pulse allows the ADCs to be used in a stand-alone manner (see the Parallel Interface section.)

The AD7822 and AD7825 are available in 20-lead and 24-lead, 0.3" wide, plastic dual in-line packages (PDIP); 20-lead and 24-lead standard small outline packages (SOIC); and 20-lead and 24-lead thin shrink small outline packages (TSSOP). The AD7829 is available in a 28-lead, 0.6" wide PDIP; a 28-lead SOIC; and a 28-lead TSSOP.