8-Bit, 1 MSPS, Low Power Successive Approximation ADC Which Operates From A Single 2.35 V to 5.25 V Power Supply

The AD7476 / AD7477 / AD7478 are, respectively, 12-bit, 10-bit, and 8-bit, high speed, low power, successive approximation ADCs. The parts operate from a single 2.35 V to 5.25 V power supply and feature throughput rates up to 1 MSPS. Each part contains a low noise, wide bandwidth track-and-hold amplifier that can handle input frequencies in excess of 6 MHz.

The conversion process and data acquisition are controlled using CS 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 initiated at this point. There are no pipeline delays associated with these parts.

The AD7476 / AD7477 / AD7478 use advanced design techniques to achieve very low power dissipation at high throughput rates. The reference for the parts is taken internally from VDD. This allows the widest dynamic input range to the ADC. Thus, the analog input range for the parts are 0 V to VDD. The conversion rate is determined by the SCLK.

PRODUCT HIGHLIGHTS

* First 12-/10-/8-Bit ADCs in SOT-23 Packages.

* High Throughput with Low Power Consumption.

* Flexible Power/Serial Clock Speed Management. The

conversion rate is determined by the serial clock, allowing

the conversion time to be reduced through the serial clock

speed increase. This allows the average power consumption

to be reduced while not converting. The parts also feature a

shutdown mode to maximize power efficiency at lower

throughput rates. Current consumption is 1 μA maximum

when in shutdown mode.

* Reference Derived from the Power Supply.

* No Pipeline Delay. The parts feature a standard successive-approximation ADC with accurate control of the sampling

instant via a CS input and once-off conversion control.

APPLICATIONS

* Battery-powered systems

Personal digital assistants

Medical instruments

Mobile communications

* Instrumentation and control systems

* Data acquisition systems

* High speed modems

* Optical sensors

* Fast Throughput Rate: 1 MSPS

* Specified for VDD of 2.35 V to 5.25 V

* Low Power:

3.6 mW Typ at 1 MSPS with 3 V Supplies

15 mW Typ at 1 MSPS with 5 V Supplies

* Wide Input Bandwidth: 70 dB SNR at 100 kHz Input Frequency