REV. 0

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a

ADT14

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 617/329-4700

World Wide Web Site: http://www.analog.com

Fax: 617/326-8703

© Analog Devices, Inc., 1997

Quad Setpoint, Programmable

Temperature Monitor and Controller

FUNCTIONAL BLOCK DIAGRAM

VOLTAGE

REFERENCE

AND

SENSOR

CURRENT

MIRROR

WINDOW

COMPARATORS

HYSTERESIS

VOLTAGE

TEMPERATURE

OUTPUT

HYSTERESIS

SETPOINT

OUTPUT 1

SETPOINT

OUTPUT 2

SETPOINT

OUTPUT 3

SETPOINT

OUTPUT 4

VPTAT

2.5V

SET 1

SET 2

SET 3

SET 4

GND

V+

ADT14

PIN CONFIGURATIONS

DIP & SO

14

13

12

11

16

15

10

9

8

1

2

3

4

7

6

5

TOP VIEW

(Not to Scale)

ADT14

NC = NO CONNECT

OUTPUT 1

V+

2.5V REFERENCE

SETPOINT 4

OUTPUT 4

SETPOINT 1

NC

NC

SETPOINT 3

HYSTERESIS

NC

GROUND

VPTAT

SETPOINT 2

OUTPUT 2

OUTPUT 3

FEATURES

Four Programmable Temperature Setpoints

Programmable Thermal Hysteresis

Accuracy

3 C Typ from –40 C to +125 C

Temperature Output Scale Factor = 5 mV/K

Resistor Programmable Temperature Setpoints

5 mA Open-Collector Setpoint Outputs

Internal 2.5 V Reference

600

A Max Quiescent Current at +5 V

APPLICATIONS

Power Supply Monitor and Control System

Multiple Fan Controller System

Workstation Thermal Management System

GENERAL DESCRIPTION

The ADT14 is a temperature sensor and controller that generates

an output voltage proportional to temperature and provides four

temperature trip points. The four trip points, or temperature

setpoints, and their hysteresis are determined by voltage levels set

by the user. An on-chip voltage reference provides an easy method

for setting the temperature trip points.

The ADT14 consists of a bandgap voltage reference combined

with four matched comparators. The reference provides both a

temperature-stable 2.5 V output, and a voltage proportional to

absolute temperature (VPTAT) which has a precise temperature

coefficient of 5 mV/K = 5 mV/(

°C +273.15). The VPTAT out-

put is nominally 1.49 V at +25

°C. The comparators determine

whether the VPTAT output is above the voltages set up by

external resistive dividers (temperature trip points) and generate

an open-collector output signal when one of their respective

thresholds has been exceeded.

Hysteresis is programmed by a user-selected voltage at the hys-

teresis pin. This voltage adjusts the hysteresis current which is

used to generate a hysteresis offset voltage. The comparator’s

noninverting inputs are connected in parallel, which guarantees

that there is no hysteresis overlap and eliminates erratic transi-

tions between adjacent trip zones.

Using a proprietary thin-film resistor process in conjunction

with production laser trimming, a temperature accuracy of

±3°C

at 25

°C is guaranteed. The open-collector outputs are capable

of sinking 5 mA, and provide TTL/CMOS logic compatibility

with an external pull-up resistor. Operating from a single 5 V

supply, the quiescent current is 600

µA max.

The ADT14 is available in the 16-lead epoxy DIP and SO

(small outline) packages.