AD7817 Analog Devices Data Sheet Manual

Single- and 4-Channel, 9
s, 10-Bit ADCs with On-Chip Temperature Sensor

AD7816/AD7817/AD7818 FUNCTIONAL BLOCK DIAGRAMFEATURES

10-Bit ADC with 9
s Conversion Time

REFIN VDD

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

AD7817

Input Channels

BOVERTEMP A > B OTI

The AD7816 Is a Temperature Measurement Only Device TEMP REG

SENSOR

On-Chip Temperature Sensor

CHARGE

REF DATA

Resolution of 0.25C REDISTRIBUTION DOUT

2.5V OUT

VIN1 DAC

2C Error from –40C to +85C

–55C to +125C Operating Range MUX

CONTROL CONTROL

VIN3 SAMPLING DIN

Wide Operating Supply Range LOGIC REG

CAPACITOR

VIN4 SCLK

2.7 V to 5.5 V

RD/WR

Inherent Track-and-Hold Functionality VBALANCE CLOCK

On-Chip Reference (2.5 V  1%)

Overtemperature Indicator DGND BUSY CONVSTAGND

Automatic Power-Down at the End of a Conversion Low Power Operation 4
W at a Throughput Rate of 10 SPS 40
W at a Throughput Rate of 1 k SPS

The AD7816, AD7817, and AD7818 have a flexible serial

400
W at a Throughput Rate of 10 k SPS

interface that allows easy interfacing to most microcontrollers.

Flexible Serial Interface

The interface is compatible with the Intel 8051, Motorola APPLICATIONS SPI® and QSPI™ protocols and National Semiconductors Ambient Temperature Monitoring (AD7816) MICROWIRE™ protocol. For more information refer to the Thermostat and Fan Control Serial Interface section of this data sheet.

High Speed Microprocessor

The AD7817 is available in a narrow body 0.15" 16-lead small

Temperature Measurement and Control www.BDTIC.com/ADI

outline IC (SOIC), in a 16-lead, thin shrink small outline pack-

Data Acquisition Systems with Ambient Temperature

age (TSSOP), while the AD7816/AD7818 come in an 8-lead

Monitoring (AD7817 and AD7818)

small outline IC (SOIC) and an 8-lead microsmall outline IC

Industrial Process Control

(MSOP).

Automotive Battery Charging Applications

PRODUCT HIGHLIGHTS 1. The devices have an on-chip temperature sensor that allows an accurate measurement of the ambient temperature to be

GENERAL DESCRIPTION

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

The AD7818 and AD7817 are 10-bit, single- and 4-channel A/D converters with on-chip temperature sensor that can oper- 2. An overtemperature indicator is implemented by carrying out a ate from a single 2.7 V to 5.5 V power supply. Each part con- digital comparison of the ADC code for Channel 0 (tempera- tains a 9 µs successive-approximation converter based around ture sensor) with the contents of the on-chip overtemperature a capacitor DAC, an on-chip temperature sensor with an accu- register. The overtemperature indicator pin goes logic low when racy of
2°C, an on-chip clock oscillator, inherent track-and- a predetermined temperature is exceeded. hold functionality and an on-chip reference (2.5 V). The

3. The automatic power-down feature enables the AD7816,

AD7816 is a temperature monitoring only device in a SOIC/

AD7817, and AD7818 to achieve superior power perfor-

MSOP package.

mance at slower throughput rates, e.g., 40 µW at 1 k SPS

The on-chip temperature sensor of the AD7817 and AD7818 throughput rate. 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.

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