LM94021

Multi-Gain Analog Temperature Sensor

General Description

The

LM94021

is

a

precision

analog

output

CMOS

integrated-circuit temperature sensor that operates at a sup-

ply voltage as low as 1.5V. While operating over the wide

temperature range of −50˚C to +150˚C, the LM94021 deliv-

ers an output voltage that is inversely porportional to mea-

sured temperature. The LM94021’s low supply current

makes it ideal for battery-powered systems as well as gen-

eral temperature sensing applications.

Two logic inputs, Gain Select 1 (GS1) and Gain Select 0

(GS0), select the gain of the temperature-to-voltage output

transfer function. Four slopes are selectable: −5.5 mV/˚C,

−8.2 mV/˚C, −10.9 mV/˚C, and −13.6 mV/˚C. In the lowest

gain configuration (GS1 and GS0 both tied low), the

LM94021 can operate with a 1.5V supply while measuring

temperature over the full −50˚C to +150˚C operating range.

Tying both inputs high causes the transfer function to have

the largest gain of −13.6 mV/˚C for maximum temperature

sensitivity. The gain-select inputs can be tied directly to V

DD

or Ground without any pull-up or pull-down resistors, reduc-

ing component count and board area. These inputs can also

be driven by logic signals allowing the system to optimize the

gain during operation or system diagnostics.

Applications

n

Cell phones

n

Wireless Transceivers

n

Battery Management

n

Automotive

n

Disk Drives

n

Games

n

Appliances

Features

n

Low 1.5V operation

n

Four selectable gains

n

Very accurate over wide temperature range of −50˚C to

+150˚C

n

Low quiescent current

n

Output is short-circuit protected

n

Extremely small SC70 package

n

Footprint compatible with the industry-standard LM20

temperature sensor

Key Specifications

1.5V to 5.5V

9 µA (typ)

Accuracy

20˚C to 40˚C

-50˚C to 70˚C

-50˚C to 90˚C

-50˚C to 150˚C

Temperature

−50˚C to 150˚C

Connection Diagram

SC70-5

20108601

Top View

See NS Package Number MAA05A

Typical Transfer Characteristic

Output Voltage vs Temperature

20108624

February 2005

© 2005 National Semiconductor Corporation

DS201086

www.national.com