AD7904,pdf,datasheet (4-Channel, 1 MSPS, 8-Bit A/D Converter)

The AD7904 are, respectively, 8-bit, 10-bit, and 12-bit, high speed, low power, 4-channel successive approxi-mation ADCs. The parts operate from a single 2.7 V to 5.25 V power supply and feature throughput rates up to 1 MSPS. The parts contain a low noise, wide bandwidth track-and-hold amplifier that can handle input frequencies in excess of 8 MHz.

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

The AD7904/AD7914/AD7924 use advanced design techniques to achieve very low power dissipation at maximum throughput rates. At maximum throughput rates, the AD7904consume 2 mA maximum with 3 V supplies; with 5 V supplies, the current consumption is 2.7 mA maximum.

Through the configuration of the control register, the analog input range for the part can be selected as 0 V to REF_IN or 0 V to 2 × REF_IN, with either straight binary or twos complement output coding. The AD7904each feature four single-ended analog inputs with a channel sequencer to allow a pre-programmed selection of channels to be converted sequentially.

The conversion time for the AD7904is determined by the SCLK frequency, which is also used as the master clock to control the conversion.