AD7922:  2-Channel, 2.35 V to 5.25 V, 1 MSPS, 12-Bit A/D Converter

The AD7912/AD7922 are 10-bit and 12-bit, high speed, low power, 2-channel, successive-approximation ADCs respectively. The parts operate from a single 2.35 V to 5.25 V power supply and feature throughput rates up to 1 MSPS. The parts contain a low-noise, wide bandwidth track/hold amplifier, which can handle input frequencies in excess of 6 MHz.

The conversion process and data acquisition are controlled using CS and the serial clock, allowing the devices to interface with microprocessors or DSPs. The input signal is sampled on the falling edge of CS and the conversion is also initiated at this point. There are no pipeline delays associated with the part.

The channel to be converted is selected through the DIN pin and the mode of operation is controlled by CS. The serial data stream from the DOUT pin has a channel identifier bit and a mode identifier bit, which provide information about the channel converted and the current mode of operation.

As a result of the Daisy Chain mode of operation, several AD7912/AD7922 can be connected together in Daisy Chain configuration. The Daisy Chain mode allows the user to read the conversion result from the ADCs contained in the chain.

The AD7912/AD7922 use advanced design techniques to achieve very low power dissipation at high throughput rates.

The reference for the part is taken internally from V_DD. This allows the widest dynamic input range to the ADC. Thus the analog input range for the part is 0 to V_DD. The conversion rate is determined by the SCLK signal.