LM73

2.7V, SOT-23, 11-to-14 Bit Digital Temperature Sensor

with 2-Wire Interface

General Description

The LM73 is an integrated, digital-output temperature sensor

featuring an incremental Delta-Sigma ADC with a two-wire

interface that is compatible with the SMBus and I

faces. The host can query the LM73 at any time to read

temperature. Available in a 6-pin SOT-23 package, the LM73

occupies very little board area while operating over a wide

accuracy from -10˚C to 80˚C. The user can optimize be-

tween the conversion time and the sensitivity of the LM73 by

programming it to report temperature in any of four different

resolutions. Defaulting to 11-bit mode (0.25˚C/LSB), the

LM73 measures temperature in a maximum time of 14 ms,

making it ideal for applications that require temperature data

very soon after power-up. In its maximum resolution, 14-bit

mode (0.03125˚C/LSB), the LM73 is optimized to sense very

small changes in temperature.

A single multi-level address line selects one of three unique

device addresses. An open-drain ALERT output goes active

when the temperature exceeds a programmable limit. Both

the data and clock lines are filtered for excellent noise toler-

ance and reliable communication. Additionally, a time-out

feature on the clock and data lines causes the LM73 to

automatically reset these lines if either is held low for an

extended time, thus exiting any bus lock-up condition without

processor intervention.

Applications

n

Portable Electronics

n

Notebook Computers

n

Automotive

n

System Thermal Management

n

Office Electronics

Key Specifications

2.7V to 5.5V

operating

320 µA (typ)

495 µA (max)

shutdown

8 µA (max)

1.9 µA (typ)

−10˚C to 80˚C

Accuracy

−25˚C to 115˚C

−40˚C to 150˚C

0.25˚C to

0.03125˚C

11-bit (0.25˚C)

14 ms (max)

14-bit (0.03125˚C)

112 ms (max)

Features

n

Single address pin offers choice of three selectable

addresses per version for a total of six possible

addresses.

n

SMBus and I

n

Supports 400 kHz operation

n

Shutdown mode with one-shot feature available for very

low average power consumption

n

Programmable digital temperature resolution from 11

bits to 14 bits.

n

Fast conversion rate ideal for quick power up and

measuring rapidly changing temperature

n

Open-drain ALERT output pin goes active when

temperature is above a programmed temperature limit

n

Very stable, low-noise digital ouput.

Typical Application

20147803

I2C is a registered trademark of Philips Electronics N.V. Corporation

October 2005

© 2005 National Semiconductor Corporation

DS201478

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