LM75 Digital Temperature Sensor and Thermal Watchdog with Two-Wire Interface
January 29, 2009
LM75
Digital Temperature Sensor and Thermal Watchdog with
Two-Wire Interface
General Description
The LM75A, LM75B and LM75C are a family of industy-stan-
dard digital temperature sensors with an integrated Sigma-
Delta analog-to-digital converter and I
2
C
®
interface. The
LM75 provides 9-bit digital temperature readings with an ac-
curacy of ±2°C from -25°C to 100°C and ±3°C over -55°C to
125°C.
The LM75A operates with a single supply from +2.7V to
+5.5V. Communication is accomplished over a 2-wire inter-
face which operates up to 400kHz. The LM75 has three
address pins, allowing up to eight LM75 devices to operate
on the same 2-wire bus. The LM75 has a dedicated over-
temperature output (O.S.) with programmable limit and hys-
tersis. This output has programmable fault tolerance, which
allows the user to define the number of consecutive error
conditions that must occur before O.S. is activated.
The wide temperature and supply range and I
2
C interface
make the LM75 ideal for a number of applications including
base stations, electronic test equipment, office electronics,
personal computers, and any other system where thermal
management is critical to performance. The LM75A, LM75B
and LM75C are available in an SOP-8 pacakage. The LM75B
and LM75C are available in an MSOP-8 package.
Applications
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■
■
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General System Thermal Management
Communications Infrastructure
Electronic Test Equipment
Environmental Monitoring
Features
■
■
■
■
No external components required
Shutdown mode to minimize power consumption
Up to eight LM75s can be connected to a single bus
Power up defaults permit stand-alone operation as
thermostat
■
UL Recognized Component (LM75B and LM75C)
Key Specifications
■
Supply Voltage
■
Supply Current
■
Temperature Accuracy
LM75A
LM75B, LM75C
operating
shutdown
−25°C to 100°C
−55°C to 125°C
2.7V to 5.5V
3.0V to 5.5V
280 μA
(typ)
4 μA
(typ)
±2°C (max)
±3°C (max)
Simplified Block Diagram
1265801
I
2
C® is a registered trademark of Philips Corporation.
© 2009 National Semiconductor Corporation
12658
www.national.com
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