GENERAL DESCRIPTION

The AD7817/AD7818 are 10-bit, single- and 4-channel analog-to-digital converters (ADCs) with an on-chip temperature sensor that can operate from a single 2.7 V to 5.5 V power supply. Each part contains a 9 µs successive approximation converter based around a capacitor digital-to-analog converter (DAC), an on-chip temperature sensor with an accuracy of ±2°C, an on-chip clock oscillator, inherent track-and-hold functionality, and an on-chip reference (2.5 V).

The on-chip temperature sensor of the AD7817/AD7818 can be accessed via Channel 0. When Channel 0 is selected and a conversion is initiated, the resulting ADC code at the end of the conversion gives a measurement of the ambient temperature with a resolution of ±0.25°C. See the Temperature Measurement section.

The AD7817/AD7818 have a flexible serial interface that allows easy interfacing to most microcontrollers. The interface is compatible with the Intel 8051, Motorola SPI and QSPI, and National Semiconductors MICROWIRE protocols. For more information, refer to the AD7817 Serial Interface section and the AD7818 Serial Interface Mode section.

The AD7817 is available in a narrow body, 0.15 inch, 16-lead SOIC and a 16-lead TSSOP, and the AD7818 comes in an 8-lead SOIC and an 8-lead MSOP.

FEATURES

10-bit ADC with 9 µs conversion time

1 AD7818 and 4 AD7817 single-ended analog input channels

On-chip temperature sensor

Resolution of 0.25°C

±2°C error from −40°C to +85°C

−55°C to +125°C operating range

Wide operating supply range: 2.7 V to 5.5 V

Inherent track-and-hold functionality

On-chip reference (2.5 V ± 1)

Overtemperature indicator

Automatic power-down at the end of a conversion

Low power operation

4 µW at a throughput rate of 10 SPS

40 µW at a throughput rate of 1 kSPS

400 µW at a throughput rate of 10 kSPS

Flexible serial interface

APPLICATIONS

Data acquisition systems with ambient temperature

monitoring

Industrial process control

Automotive

Battery charging applications