Rainbow Electronics LM92 - Manual

LM92
± 0.33˚C Accurate, 12-Bit + Sign Temperature Sensor and
Thermal Window Comparator with Two-Wire Interface
General Description
The LM92 is a digital temperature sensor and thermal win-
dow comparator with an I
2 C ™ Serial Bus interface and an
accuracy of ± 0.33˚C. The window-comparator architecture
of the LM92 eases the design of temperature control sys-
tems. The open-drain Interrupt (INT) output becomes active
whenever temperature goes outside a programmable win-
dow,
while a separate Critical Temperature Alarm
(T_CRIT_A) output becomes active when the temperature
exceeds a programmable critical limit. The INT output can
operate in either a comparator or event mode, while the
T_CRIT_A output operates in comparator mode only.
The host can program both the upper and lower limits of the
window as well as the critical temperature limit. Program-
mable hysterisis as well as a fault queue are available to
minimize false tripping. Two pins (A0, A1) are available for
address selection. The sensor powers up with default thresh-
olds of 2˚C T
HYST
, 10˚C T
LOW
, 64˚C T
HIGH
, and 80˚C
T_CRIT.
The LM92’s 2.7V to 5.5V supply voltage range, Serial Bus in-
terface, 12-bit + sign output, and full-scale range of over
128˚C make it ideal for a wide range of applications. These
include thermal management and protection applications in
personal computers, electronic test equipment, office elec-
tronics, automotive, medical and HVAC applications.
Features
n Window comparison simplifies design of ACPI
compatible temperature monitoring and control.
n Serial Bus interface
n Separate open-drain outputs for Interrupt and Critical
Temperature shutdown
n Shutdown mode to minimize power consumption
n Up to 4 LM92s can be connected to a single bus
n 12-bit + sign output
n Operation up to 150˚C
Key Specifications
j Supply Voltage 2.7V to 5.5V
j Supply Current operating 350µA (typ)
625µA (max)
shutdown 5µA (typ)
j Temperature 30˚C ± 0.33˚C(max)
Accuracy 10˚C to 50˚C ± 0.50˚C(max)
−10˚C to 85˚C ± 1.0˚C(max)
125˚C ± 1.25˚C(max)
−25˚C to 150˚C ± 1.5˚C(max)
j Linearity ± 0.5˚C(max)
j Resolution 0.0625˚C
Applications
n HVAC
n Medical Electronics
n Electronic Test Equipment
n System Thermal Management
n Personal Computers
n Office Electronics
n Automotive
Simplified Block Diagram
I2C ® is a registered trademark of Philips Corporation.
DS101051-1
March 2000
LM92
±
0.33˚C
Accurate,
12-Bit
+
Sign
T
emperature
Sensor
and
Thermal
W
indow
Comparator
with
T
wo-W
ire
Interface
© 2000 National Semiconductor Corporation DS101051 www.national.com