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 through put 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.

Several AD7912 / AD7922 can be connected together in a daisy chain. The AD7912 / AD7922 feature a daisy-chain mode that allows the user to read the conversion results 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 VDD, thereby allowing the widest dynamic input range to the ADC.

PRODUCT HIGHLIGHTS

* 2-channel, 1 MSPS, 10-/12-bit ADCs in TSOT package.

* High throughput with low power consumption.

* Flexible power/serial clock speed management.

The conversion rate is determined by the serial clock. The

parts also feature a power-down mode to maximize power

efficiency at lower throughput rates. Average power

consumption is reduced when the power-down mode is

used while not converting. Current consumption is 1 µA

maximum and 50 nA typically when in power-down mode.

* Daisy-chain mode.

* 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:

4.8 mW typ at 1 MSPS with 3 V Supplies

15.5 mW typ at 1 MSPS with 5 V Supplies

* Wide Input Bandwidth:

71.4 dB min SNR at 100 kHz Input Frequency

* Flexible Power/Serial Clock Speed Management