LM88 Factory Programmable Dual Remote-Diode Thermostat
August 2001
LM88
Factory Programmable Dual Remote-Diode Thermostat
General Description
The LM88 is a dual remote-diode temperature sensor with 3
digital comparators. The LM88 has 3 open-drain outputs
(O_SP0, O_SP1 and O_CRIT) that can be used as inter-
rupts or to signal system shutdown. The digital comparators
can be factory programmed to make a greater than or less
than comparison. When programmed for a greater than
comparison outputs:
O_SP0 and O_SP1 activate when the temperatures mea-
sured by D0 or D1 exceed the associated setpoints of
T_SP0 or T_SP1.
O_CRIT activates when the temperature measured by
either D0 or D1 exceeds setpoint T_CRIT.
T_CRIT can be set at 1藲C intervals from 鈭?0藲C to +125藲C.
T_SP0 and T_SP1 can be set at 4藲C intervals in the range of
T_CRIT +127藲C/鈭?28藲C. Hysteresis for all comparators is
set to 1藲C. O_CRIT, in conjunction with T_CRIT, could be
used to prevent catastrophic damage to key subsystems
such as notebook Card Bus cards while O_SP0 and O_SP1,
in conjunction with T_SP0 and T_SP1, can warn of an
impending failure.
The LM88 is available in an 8-lead mini-small-outline pack-
age.
Features
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2 external remote diode input channels
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3 digital comparator outputs, 1 per remote diode and
one T_CRIT common to both
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Factory programmable greater than or less than
comparisons
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1藲C comparator hysteresis
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2 setpoints, T_SP0 and T_SP1, factory programmable in
4藲C intervals
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1 setpoint, T_CRIT, factory programmable in 1藲C
intervals
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Active Low open-drain digital outputs
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8-pin mini-SO plastic package
Key Specifications
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Power Supply Voltage
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Power Supply Current
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LM88 Temperature Range
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Diode Setpoint Temperature
2.8V鈥?.8V
1.5 mA (max)
鈭?0藲C to +85藲C
0藲C to +125藲C
Range
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Temperature Trip Point Accuracy:
Diode Junction
Temperature
(T
DJ
)
LM88CIM
Accuracy
LM88CIM
Temperature
Range
鈭?0藲C to +85藲C
鈭?0藲C to +85藲C
Applications
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Microprocessor Thermal Management
Appliances
Portable Battery Powered Systems
Fan Control
Industrial Process Control
HVAC Systems
Remote Temperature Sensing
Electronic System Protection
+45藲C to +85藲C
+60藲C to +100藲C
鹵
3藲C (max)
鹵
3藲C (max)
Note: These are sample ranges. Contact factory for other
ranges.
Simplified Block Diagram and Connection Diagram
MSOP-8/MUA08A Package
10132601
10132602
Top View
For simplicity, the effects of the hysteresis are not shown in the
temperature response diagram.
漏 2001 National Semiconductor Corporation
DS101326
www.national.com
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