Temperature Sensor (On Chip) 4-Channel, 9 s, 10-Bit ADC

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).

PRODUCT HIGHLIGHTS

* The devices have an on-chip temperature sensor that allows

an accurate measurement of the ambient temperature to be

made. The measurable temperature range is −55°C to +125°C.

* An overtemperature indicator is implemented by carrying out a

digital comparison of the ADC code for Channel 0 (temperature

sensor) with the contents of the on-chip overtemperature

register. The overtemperature indicator pin goes logic low

when a predetermined temperature is exceeded.

* The automatic power-down feature enables the AD7817 and

AD7818 to achieve superior power performance at slower

throughput rates, that is, 40 μW at 1 kSPS throughput rate.

APPLICATIONS

* Data acquisition systems with ambient temperature monitoring

* Industrial process control

* Automotive

* Battery charging applications

* 10-Bit ADC with 9 µs Conversion Time

* 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