October 2005
LM73
2.7V, SOT-23, 11-to-14 Bit Digital Temperature Sensor
with 2-Wire Interface
General Description
Key Specifications
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 I2C® inter-
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
temperature range (-40˚C to 150˚C) and providing 1.0˚C
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.
j
Supply Voltage
2.7V to 5.5V
320 µA (typ)
495 µA (max)
8 µA (max)
1.9 µA (typ)
1.0˚C (max)
1.5˚C (max)
2.0˚C (max)
0.25˚C to
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Supply Current
operating
shutdown
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Temperature
−10˚C to 80˚C
−25˚C to 115˚C
−40˚C to 150˚C
Accuracy
j
j
Resolution
0.03125˚C
Conversion Time
11-bit (0.25˚C)
14 ms (max)
14-bit (0.03125˚C) 112 ms (max)
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.
Features
n Single address pin offers choice of three selectable
addresses per version for a total of six possible
addresses.
n SMBus and I2C-compatible two-wire interface
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.
Applications
n Portable Electronics
n Notebook Computers
n Automotive
n System Thermal Management
n Office Electronics
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
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C is a registered trademark of Philips Electronics N.V. Corporation
© 2005 National Semiconductor Corporation
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