2-15

TELCOM SEMICONDUCTOR, INC.

7

6

5

4

3

1

2

8

TC620

TC621

TC620/1-9 11/4/96

FUNCTIONAL BLOCK DIAGRAM

3

HIGH SET

2

LOW SET

5

CONTROL*

6

HIGH LIMIT

7

LOW LIMIT

8

4

*Suffix code "C" denotes cooling option (high true CONTROL output);

suffix code "H" denotes heating option (low true CONTROL output).

Q

S

R

Q

+

+

–

–

TC620

HIGH SET

LOW SET

1

THERMISTOR

CONTROL*

HIGH LIMIT

LOW LIMIT

Temp

to

Voltage

Converter

GEN

GEN

3

2

5

6

7

8

4

Q

S

R

Q

+

+

–

–

TC621

Thermistor

Interface

Circuit

GEN

GEN

Ambient

Part No.

Package

Temperature

TC621x*EOA

8-Pin SOIC

– 40

°C to +85°C

TC621x*EPA

8-Pin Plastic DIP

– 40

°C to +85°C

5V, DUAL TRIP POINT TEMPERATURE SENSORS

FEATURES

s

User-Programmable Hysteresis and Temperature

Set Point

s

Easily Programs with 2 External Resistors

s

Wide Temperature Detection

Range ................ – 40

s

External Thermistor for Remote Sensing

Applications (TC621x)

APPLICATIONS

s

Power Supply Overtemperature Detection

s

Consumer Equipment

s

Temperature Regulators

s

CPU Thermal Protection

ORDERING INFORMATION

Ambient

Part No.

Package

Temperature

TC620x*COA

8-Pin SOIC

0

°C to +70°C

TC620x*CPA

8-Pin Plastic DIP

0

°C to +70°C

TC620x*EOA

8-Pin SOIC

– 40

°C to +85°C

TC620x*EPA

8-Pin Plastic DIP

– 40

°C to +85°C

TC620CVOA

8-Pin SOIC

– 40

°C to +125°C

TC621x*COA

8-Pin SOIC

0

°C to +70°C

TC621x*CPA

8-Pin Plastic DIP

0

°C to +70°C

*The part code will be C or H (see Functional Block Diagram, below,

and page 2).

GENERAL DESCRIPTION

The TC620 and TC621 are programmable logic output

temperature detectors designed for use in thermal manage-

ment applications. The TC620 features an on-board tem-

perature sensor, while the TC621 connects to an external

NTC thermistor for remote sensing applications.

Both devices feature dual thermal interrupt outputs

(HIGH LIMIT and LOW LIMIT), each of which program with

a single external resistor. On the TC620, these outputs are

driven active (high) when measured temperature equals the

user-programmed limits. The CONTROL (hysteresis) out-

put is driven high when temperature equals the high limit

setting, and returns low when temperature falls below the

low limit setting. This output can be used to provide simple

ON/OFF control to a cooling fan or heater. The TC621

provides the same output functions except that the logical

states are inverted.

The TC620/621 are usable over a maximum tempera-

ture range of – 40

°C to +125°C.