1FEATURES

2• Internal Comparator with Pin Selectable 2°C or

10°C Hysteresis

• No External Components Required

• Open-drain or Push-pull Digital Output;

Supports CMOS Logic Levels

• Internal Temperature Sensor with V TEMP Output Pin

• VTEMP Output Allows After-assembly System

Testing

• Internal Voltage Reference and DAC for Trip-

point Setting

• Currently Available in 5-pin SOT-23 Plastic

Package

• Excellent Power Supply Noise Rejection

APPLICATIONS

• Microprocessor Thermal Management

• Appliances

• Portable Battery Powered Systems

• Fan Control

• Industrial Process Control

• HVAC Systems

• Electronic System Protection

KEY SPECIFICATIONS

• Power Supply Voltage 2.7V to 5.5V

• Power Supply Current 40μA (Max), 15μA (Typ)

• Hysteresis Temperature 2°C or 10°C (Typ)

• Temperature Trip Point Accuracy ±3°C (Max)

DESCRIPTION

The LM27 is a precision, single digital-output, low-

power thermostat comprised of an internal reference,

DAC, temperature sensor and comparator. Utilizing

factory programming, it can be manufactured with

different trip points as well as different digital output

functionality. The trip point (TOS) can be preset at the

factory to any temperature in the range of +120°C to

+150°C in 1°C increments. The LM27 has one digital output (OS/OS/US/US), one digital input (HYST) and

one analog output (VTEMP). The digital output stage

can be preset as either open-drain or push-pull. In

addition, it can be factory programmed to be active

HIGH or LOW. The digital output can be factory

programmed to indicate an over temperature shutdown event (OS or OS) or an under temperature

shutdown event (US or US). When preset as an

overtemperature shutdown (OS) it will go LOW to

indicate that the die temperature is over the internally

preset TOS and go HIGH when the temperature goes

below (TOS–THYST). Similarly, when preprogrammed

as an undertemperature shutdown (US) it will go

HIGH to indicate that the temperature is below TUS

and go LOW when the temperature is above

(TUS+THYST). The typical hysteresis, THYST, can be set to 2°C or 10°C and is controlled by the state of the

HYST pin. A VTEMP analog output provides a voltage

that is proportional to temperature and has a

−10.7mV/°C output slope.

Currently, there are several standard parts available,

see Table 1. For other part options, contact a Texas

Instruments Distributor or Sales Representative for information on minimum order qualification. The

LM27 is currently available in a 5-lead SOT-23

package.