8-Channel, 12-Bit ADC with IC Compatible Interface in 20-Lead TSSOP

The AD7997 / AD7998 are 8-channel, 10- and 12-bit, low power, successive approximation ADCs with an I2C-compatible interface. The parts operate from a single 2.7 V to 5.5 V power supply and feature a 2 µs conversion time. The parts contain an 8-channel multiplexer and track-and-hold amplifier that can handle input frequencies up to 11 MHz.

The AD7997 / AD7998 provide a 2-wire serial interface that is compatible with I2C interfaces. Each part comes in two versions, AD7997-0 / AD7998-0 and AD7997-1 / AD7998-1, and each version allows at least two different I2C addresses. The I2C interface on the AD7997-0/AD7998-0 supports standard and fast I2C interface modes. The I2C interface on the AD7997-1 / AD7998-1 supports standard, fast, and high speed I2C interface modes.

The AD7997 / AD7998 normally remain in a shutdown state while not converting, and power up only for conversions. The conversion process can be controlled using the CONVST pin, by a command mode where conversions occur across I2C write operations or an automatic conversion interval mode selected through software control.

The AD7997 / AD7998 require an external reference that should be applied to the REFIN pin and can be in the range of 1.2 V to VDD. This allows the widest dynamic input range to the ADC.

On-chip limit registers can be programmed with high and low limits for the conversion result, and an open-drain, out-of-range indicator output (ALERT) becomes active when the programmed high or low limits are violated by the conversion result. This output can be used as an interrupt.

PRODUCT HIGHLIGHTS

* 2 µs conversion time with low power consumption.

* I2C-compatible serial interface with pin-selectable

addresses. Two AD7997/AD7998 versions allow five

AD7997/AD7998 devices to be connected to the same

serial bus.

* The parts feature automatic shutdown while not converting

to maximize power efficiency. Current consumption is 1 µA

max when in shutdown mode at 3V.

* Reference can be driven up to the power supply.

* Out-of-range indicator that can be software disabled or

enabled.

* One-shot and automatic conversion rates.

* Registers store minimum and maximum conversion

results.

* 12-Bit ADC with Fast Conversion Time: 2 µs

* Eight Single-Ended Analog Input Channels

* Specified for VDD of 2.7 V to 5.5 V

* Low Power Consumption

* Fast Throughput Rate: - 188 kSPS

* Sequencer Operation

* Automatic Cycle Mode