National Semiconductor LM26 Series Manual

LM26
±
SOT-23, 3˚C Accurate, Factory Preset Thermostat
General Description
The LM26 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
can be preset at the factory to any temperature in the range
of −55˚C to +110˚C in 1˚C increments. The LM26 has one
digital output (OS/OS/US/US), one digital input (HYST) and
one analog output (V ). The digital output stage can be
TEMP
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
HIGH when the temperature goes below (T
larly, when preprogrammed as an undertemperature shut-
down (US) it will go HIGH to indicate that the temperature is
below T and go LOW when the temperature is above
US
(T +T ). The typical hysteresis, T
US HYST
2˚C or 10˚C and is controlled by the state of the HYST pin. A
V analog output provides a voltage that is proportional
TEMP
to temperature and has a −10.82mV/˚C output slope.
Available parts are detailed in the ordering information. For
other part options, contact a National Semiconductor Dis-
tributor or Sales Representative for information on minimum
order qualification. The LM26 is currently available in a
5-lead SOT-23 package.
Applications
n Microprocessor Thermal Management
n Appliances
LM26CIM5-TPA Simplified Block Diagram and Connection Diagram
please see ordering information or contact National Semiconductor.
© 2003 National Semiconductor Corporation
n Portable Battery Powered Systems
n Fan Control
n Industrial Process Control
n HVAC Systems
n Remote Temperature Sensing
n Electronic System Protection
)
OS
Features
n Internal comparator with pin programmable 2˚C or 10˚C
n No external components required
n Open Drain or push-pull digital output; supports CMOS
n Internal temperature sensor with V
n V
and go n Internal voltage reference and DAC for trip-point setting
OS
–T ). Simi-
n Currently available in 5-pin SOT-23 plastic package
OS HYST
n Excellent power supply noise rejection
Key Specifications
, can be set to
HYST
j
j
j
The LM26CIM5-TPA has a fixed trip point of 85˚C.
For other trip point and output function availability,
DS101323
hysteresis
logic levels
output allows after-assembly system testing
TEMP
Power Supply Voltage
Power Supply Current
Hysteresis Temperature
Temperature Trip Point Accuracy
Temperature Range
−55˚C to +110˚C
+120˚C
May 2001
output pin
TEMP
2.7V to 5.5V
40µA(max)
20µA(typ)
2˚C or 10˚C(typ)
LM26CIM
±
3˚C (max)
±
4˚C (max)
10132301
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