4-Channel, 1 MSPS, 8-Bit A/D Converter with Sequencer in 16-Lead TSSOP

The AD7904 / AD7914 / AD7924 are, respectively, 8-bit, 10-bit, and 12-bit, high speed, low power, 4-channel successive approximation 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 AD7904 / AD7914 / AD7924 consume 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 REFIN or 0 V to 2 × REFIN, with either straight binary or twos complement output coding. The AD7904 / AD7914 / AD7924 each 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 AD7904 / AD7914 / AD7924 is determined by the SCLK frequency, which is also used as the master clock to control the conversion.

PRODUCT HIGHLIGHTS

* High Throughput with Low Power Consumption.

The AD7904/AD7914/AD7924 offer throughput rates

up to 1 MSPS. At the maximum throughput rate with 3 V

supplies, the AD7904/AD7914/AD7924 dissipate only

6 mW of power maximum.

* Four Single-Ended Inputs with Channel Sequencer.

A consecutive sequence of channels can be selected,

through which the ADC will cycle and convert on.

* Single-Supply Operation with VDRIVE Function.

The AD7904/AD7914/AD7924 operate from a single 2.7 V

to 5.25 V supply. The VDRIVE function allows the serial interface to connect directly to 3 V or 5 V processor systems,

independent of VDD.

* Flexible Power/Serial Clock Speed Management.

The conversion rate is determined by the serial clock,

allowing the conversion time to be reduced by increasing

the serial clock speed. The parts also feature two shutdown

modes to maximize power efficiency at lower throughput

rates. Current consumption is 0.5 µA maximum when in

full shutdown.

* No Pipeline Delay.

The parts feature a standard successive approximation

ADC with accurate control of the sampling instant via

the CS input and once-off conversion control.

* Fast throughput rate: 1 MSPS

* Specified for AVDD of 2.7 V to 5.25 V

* Low power:

6 mW maximum at 1 MSPS with 3 V supplies

13.5 mW maximum at 1 MSPS with 5 V supplies

* 4 single-ended inputs with sequencer

* Wide input bandwidth:

AD7924, 70 dB SNR at 50 kHz input frequency