Philips Semiconductors

Product data sheet

LM75A

Digital temperature sensor and thermal Watchdog

™

2

2004 Oct 05

GENERAL DESCRIPTION

The LM75A is a temperature-to-digital converter using an on-chip

band-gap temperature sensor and Sigma-delta A-to-D conversion

technique. The device is also a thermal detector providing an

over-temp detection output. The LM75A contains a number of data

registers: Configuration register (Conf) to store the device settings

such as device operation mode, OS operation mode, OS polarity

and OS fault queue as described in the functional description

section; temperature register (Temp) to store the digital temp

reading, and set-point registers (Tos & Thyst) to store programmable

overtemp shutdown and hysteresis limits, that can be communicated

also includes an open-drain output (OS) which becomes active

when the temperature exceeds the programmed limits. There are

three selectable logic address pins so that eight devices can be

connected on the same bus without address conflict.

The LM75A can be configured for different operation conditions. It

can be set in normal mode to periodically monitor the ambient

temperature, or in shutdown mode to minimize power consumption.

The OS output operates in either of two selectable modes: OS

comparator mode and OS interrupt mode. Its active state can be

selected as either HIGH or LOW. The fault queue that defines the

number of consecutive faults in order to activate the OS output is

programmable as well as the set-point limits.

The temperature register always stores an 11-bit 2’s complement

data giving a temperature resolution of 0.125

°C. This high

temperature resolution is particularly useful in applications of

measuring precisely the thermal drift or runaway.

The device is powered-up in normal operation mode with the OS in

comparator mode, temperature threshold of 80

°C and hysteresis of

75

°C, so that it can be used as a stand-alone thermostat with those

pre-defined temperature set points.

FEATURES

improved temperature resolution of 0.125

°C and specification of

a single part over power supply range from 2.8 V to 5.5 V.

±2 °C from –25 °C to +100 °C

±3 °C from –55 °C to +125 °C

conservation

200 V MM per JESD22-A115 and 1000 V CDM per JESD22-C101

exceeds 100 mA

APPLICATIONS

ORDERING INFORMATION

TYPE NUMBER

Topside mark

PACKAGE

TYPE NUMBER

Topside mark

NAME

DESCRIPTION

VERSION

LM75AD

LM75A

SO8

plastic small outline package; 8 leads; body width 3.9 mm

SOT96-1

LM75ADP

LM75A

TSSOP8

plastic thin shrink small outline package; 8 leads; body width 3 mm

SOT505-1

WATCHDOG

™ is a trademark of National Semiconductor Corporation.