October 2005
LM75
Digital Temperature Sensor and Thermal Watchdog with
Two-Wire Interface
n Register readback capability
n Power up defaults permit stand-alone operation as
General Description
The LM75 is a temperature sensor, Delta-Sigma analog-to-
thermostat
digital converter, and digital over-temperature detector with
n Shutdown mode to minimize power consumption
n Up to 8 LM75s can be connected to a single bus
n UL Recognized Component
I2C® interface. The host can query the LM75 at any time to
read temperature. The open-drain Overtemperature Shut-
down (O.S.) output becomes active when the temperature
exceeds a programmable limit. This pin can operate in either
“Comparator” or “Interrupt” mode.
Key Specifications
The host can program both the temperature alarm threshold
(TOS) and the temperature at which the alarm condition goes
away (THYST). In addition, the host can read back the con-
tents of the LM75’s TOS and THYST registers. Three pins (A0,
A1, A2) are available for address selection. The sensor
powers up in Comparator mode with default thresholds of
j
Supply Voltage
3.0V to 5.5V
250 µA (typ)
1 mA (max)
4 µA (typ)
2˚C(max)
j
Supply Current
operating
shutdown
j
Temperature Accuracy −25˚C to 100˚C
−55˚C to 125˚C
80˚C TOS and 75˚C THYST
.
3˚C(max)
The LM75’s 3.0V to 5.5V supply voltage range, low supply
current and I2C interface make it ideal for a wide range of
applications. These include thermal management and pro-
tection applications in personal computers, electronic test
equipment, and office electronics.
Applications
n System Thermal Management
n Personal Computers
n Office Electronics
Features
n Electronic Test Equipment
n SOP-8 and Mini SOP-8 (MSOP) packages save space
n I2C Bus interface
n Separate open-drain output pin operates as interrupt or
comparator/thermostat output
Simplified Block Diagram
01265801
2
I
C® is a registered trademark of Philips Corporation.
© 2005 National Semiconductor Corporation
DS012658
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