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 1C intervals from 40C to +125C.
T_SP0 and T_SP1 can be set at 4C intervals in the range of
T_CRIT +127C/128C. Hysteresis for all comparators is
set to 1C. 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.
Applications
n
Microprocessor Thermal Management
n
Appliances
n
Portable Battery Powered Systems
n
Fan Control
n
Industrial Process Control
n
HVAC Systems
n
Remote Temperature Sensing
n
Electronic System Protection
Features
n
2 external remote diode input channels
n
3 digital comparator outputs, 1 per remote diode and
one T_CRIT common to both
n
Factory programmable greater than or less than
comparisons
n
1C comparator hysteresis
n
2 setpoints, T_SP0 and T_SP1, factory programmable in
4C intervals
n
1 setpoint, T_CRIT, factory programmable in 1C
intervals
n
Active Low open-drain digital outputs
n
8-pin mini-SO plastic package
Key Specifications
j
Power Supply Voltage
j
Power Supply Current
j
LM88 Temperature Range
j
Diode Setpoint Temperature
Range
2.8V–3.8V
1.5 mA (max)
40C to +85C
0C to +125C
j
Temperature Trip Point Accuracy:
Diode Junction
Temperature
(T
DJ
)
+45C to +85C
+60C to +100C
LM88CIM
Accuracy
LM88CIM
Temperature
Range
40C to +85C
40C to +85C
±
3C (max)
±
3C (max)
Note: These are sample ranges. Contact factory for other
ranges.
Simplified Block Diagram and Connection Diagram
MSOP-8/MUA08A Package
10132601
Top View
10132602
For simplicity, the effects of the hysteresis are not shown in the
temperature response diagram.
August 2001
L
2001 National Semiconductor Corporation
DS101326
www.national.com