
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
2
C
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 (-40C to 150C) and providing
±
1.0C
accuracy from -10C to 80C. 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 (0.25C/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 (0.03125C/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
j
Supply Voltage
j
Supply Current
2.7V to 5.5V
320 μA (typ)
495 μA (max)
8 μA (max)
1.9 μA (typ)
±
1.0C (max)
±
1.5C (max)
±
2.0C (max)
0.25C to
0.03125C
14 ms (max)
112 ms (max)
operating
shutdown
j
Temperature
Accuracy
10C to 80C
25C to 115C
40C to 150C
j
Resolution
j
Conversion Time
11-bit (0.25C)
14-bit (0.03125C)
Features
n
Single address pin offers choice of three selectable
addresses per version for a total of six possible
addresses.
n
SMBus and I
2
C-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.
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
L
2005 National Semiconductor Corporation
DS201478
www.national.com