RoHS Compliance Information	Size in Kbytes	Date
LM57 Resistor-Programmable Temperature Switch and Analog Temperature Sensor	555 Kbytes	5-Oct-09	Download

Part Number

Package

Factory Lead Time

Models

Samples & Electronic Orders

Budgetary Pricing

Std Pack Size

Package Marking Format

Type

Pins

Spec.

MSL Rating

Peak Reflow

RoHS Report

CAD Symbols

Weeks

Qty

Qty

$US each

LM57B10EB

LM57 Evaluation Board

Full production

N/A

1+

$65.00

1

-

N/A

N/A

LM57BISD-10

LLP

8

NOPB

3

260

RoHS

N/A

Full production

N/A

1K+

$1.25

reel of 1000

XYTT 57B9

12 weeks

1000

LM57BISD-5

LLP

8

NOPB

3

260

RoHS

N/A

Full production

N/A

1K+

$1.25

reel of 1000

XYTT 57B5

12 weeks

2000

LM57CISD-10

LLP

8

NOPB

3

260

RoHS

N/A

Full production

N/A

1K+

$0.89

reel of 1000

XYTT 57C9

6 weeks

2000

LM57CISD-5

LLP

8

NOPB

3

260

RoHS

N/A

Full production

N/A

1K+

$0.89

reel of 1000

XYTT 57C5

6 weeks

1000

LM57BISDX-10

LLP

8

NOPB

3

260

RoHS

N/A

Full production

N/A

1K+

$1.25

reel of 4500

XYTT 57B9

12 weeks

N/A

LM57BISDX-5

LLP

8

NOPB

3

260

RoHS

N/A

Full production

N/A

1K+

$1.25

reel of 4500

XYTT 57B5

12 weeks

N/A

LM57CISDX-10

LLP

8

NOPB

3

260

RoHS

N/A

Full production

N/A

1K+

$0.89

reel of 4500

XYTT 57C9

12 weeks

N/A

LM57CISDX-5

LLP

8

NOPB

3

260

RoHS

N/A

Full production

N/A

1K+

$0.89

reel of 4500

XYTT 57C5

12 weeks

N/A

General Description

The LM57 is a precision, dual-output, temperature switch with integrated analog temperature sensor. The trip temperature (T_TRIP) is programmable by using two external 1% resistors. Using extremely small packaged resistors (0.5 mm x 1 mm), the LM57 can be programmed to any of 256 trip temperatures while consuming very little board space. The V_TEMP output delivers an analog output voltage which is proportional with a negative temperature coefficient (NTC) to the measured temperature.

Built-in temperature hysteresis (T_HYST) keeps the output stable in an environment of thermal oscillation. The digital temperature switch outputs will go active when the die temperature exceeds T_TRIP and will release when the temperature falls below a temperature equal to T_TRIP minus T_HYST. One of the digital outputs, T_OVER, is active-high with a push-pull structure. The other digital output, ^TOVER, is active-low with an open-drain structure.

Driving the TRIP-TEST input high will make the digital outputs active. A processor can read the logic level of the temperature switch outputs, confirming that they changed to their active state. This allows for in-situ verification that the comparator and output circuitry are functional after system assembly. When the TRIP-TEST pin is high, the trip-level reference voltage appears at the Vtemp pin. The system could then use this voltage to calibrate the sensor for even tighter accuracy. Tying T_OVER to TRIP-TEST will latch the output after it trips. It can be cleared by forcing TRIP-TEST low or powering off the LM57.

As it draws only 28µA max from its supply, it has very low self-heating, about 0.02°C in still air.

Application Notes

Title	Size in Kbytes	Date
AN-1984: Application Note 1984 LM57 Temperature Switch vs Thermistors	210 Kbytes	28-Jul-09	Download