GENERAL DESCRIPTION

The AD7818 and AD7817 are 10-bit, single- and 4-channel A/D converters with 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 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 AD7816 is a temperature monitoring only device in a SOIC/MSOP package.

The on-chip temperature sensor of the AD7817 and 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 Temperature Measurement section of this data sheet.

The AD7816, AD7817, and 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™ protocols and National Semiconductors MICROWIRE™ protocol. For more information refer to the Serial Interface section of this data sheet.

The AD7817 is available in a narrow body 0.15 16-lead small outline IC (SOIC), in a 16-lead, thin shrink small outline package (TSSOP), while the AD7816/AD7818 come in an 8-lead small outline IC (SOIC) and an 8-lead microsmall outline IC (MSOP).

FEATURES

10-Bit ADC with 9 μs Conversion Time

One (AD7818) and Four (AD7817) Single-Ended Analog Input Channels

The AD7816 Is a Temperature Measurement Only Device

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

Ambient Temperature Monitoring (AD7816)

Thermostat and Fan Control

High Speed Microprocessor

Temperature Measurement and Control

Data Acquisition Systems with Ambient Temperature

Monitoring (AD7817 and AD7818)

Industrial Process Control

Automotive

Battery Charging Applications