LM27 SOT-23,
鹵
3藲C Accurate, 120藲C-150藲C Factory Preset Thermostat
August 2002
LM27
SOT-23,
鹵
3藲C Accurate, 120藲C-150藲C Factory Preset
Thermostat
General Description
The LM27 is a precision, single digital-output, low-power
thermostat comprised of an internal reference, DAC, tem-
perature sensor and comparator. Utilizing factory program-
ming, it can be manufactured with different trip points as well
as different digital output functionality. The trip point (T
OS
)
can be preset at the factory to any temperature in the range
of +120藲C to +150藲C in 1藲C increments. The LM27 has one
digital output (OS/OS/US/US), one digital input (HYST) and
one analog output (V
TEMP
). The digital output stage can be
preset as either open-drain or push-pull. In addition, it can be
factory programmed to be active HIGH or LOW. The digital
output can be factory programmed to indicate an over tem-
perature shutdown event (OS or OS) or an under tempera-
ture shutdown event (US or US). When preset as an over-
temperature shutdown (OS) it will go LOW to indicate that
the die temperature is over the internally preset T
OS
and go
HIGH when the temperature goes below (T
OS
鈥揟
HYST
). Simi-
larly, when preprogrammed as an undertemperature shut-
down (US) it will go HIGH to indicate that the temperature is
below T
US
and go LOW when the temperature is above
(T
US
+T
HYST
). The typical hysteresis, T
HYST
, can be set to
2藲C or 10藲C and is controlled by the state of the HYST pin. A
V
TEMP
analog output provides a voltage that is proportional
to temperature and has a 鈭?0.7mV/藲C output slope.
Currently, there are several standard parts available, see
ordering information for details. For other part options, con-
tact a National Semiconductor Distributor or Sales Repre-
sentative for information on minimum order qualification. The
LM27 is currently available in a 5-lead SOT-23 package.
n
n
n
n
n
Portable Battery Powered Systems
Fan Control
Industrial Process Control
HVAC Systems
Electronic System Protection
Features
n
Internal comparator with pin selectable 2藲C or 10藲C
hysteresis
n
No external components required
n
Open-drain or push-pull digital output; supports CMOS
logic levels
n
Internal temperature sensor with V
TEMP
output pin
n
V
TEMP
output allows after-assembly system testing
n
Internal voltage reference and DAC for trip-point setting
n
Currently available in 5-pin SOT-23 plastic package
n
Excellent power supply noise rejection
Key Specifications
j
Power Supply Voltage
j
Power Supply Current
j
Hysteresis Temperature
j
Temperature Trip Point Accuracy
2.7V to 5.5V
40碌A(chǔ)(max)
15碌A(chǔ)(typ)
2藲C or 10藲C(typ)
鹵
3藲C (max)
Applications
n
Microprocessor Thermal Management
n
Appliances
LM27CIM5-2HJ Simplified Block Diagram and Connection Diagram
20030701
The LM27CIM5-2HJ has a fixed trip point of 140藲C.
For other trip point and output function availability,
please see ordering information or contact National Semiconductor.
漏 2002 National Semiconductor Corporation
DS200307
www.national.com
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