8-Bit, 1 MSPS, Low-Power A/D Converter in SC70 and MSOP Packages

The AD7476A / AD7477A / AD7478A are 12-bit, 10-bit, and 8-bit high speed, low power, successive-approximation analog-todigital converters (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-and-hold amplifier that can handle input frequencies in excess of 13 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 parts. The AD7476A / AD7477A / AD7478A use advanced design techniques to achieve low power dissipation at high throughput rates. The reference for the part is taken internally from VDD to allow the widest dynamic input range to the ADC. Thus, the analog input range for the part is 0 V to VDD. The conversion rate is determined by the SCLK.

PRODUCT HIGHLIGHTS

* First 12-/10-/8-bit ADCs in a SC70 package.

* 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 when a power-down mode is used while not

converting. The parts also feature a power-down mode to

maximize power efficiency at lower throughput rates.

Current consumption is 1 µA maximum and 50 nA

typically when in power-down 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 at 1 MSPS with 3 V supplies

12.5 mW at 1 MSPS with 5 V supplies

* Wide input bandwidth

71 dB SNR at 100 kHz input frequency

* Flexible power/serial clock speed management