Rainbow Electronics LM88 User Manual

August 2001

LM88
Factory Programmable Dual Remote-Diode Thermostat

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 inter­rupts 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 mea­sured 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˚C intervals from −40˚C to +125˚C.
T_SP0 andT_SP1 can be set at 4˚C intervals in the range of
T_CRIT +127˚C/−128˚C. Hysteresis for all comparators is
set to 1˚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 pack­age.

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 1˚C comparator hysteresis
n 2 setpoints, T_SP0 and T_SP1, factory programmable in

4˚C intervals

n 1 setpoint, T_CRIT, factory programmable in 1˚C

intervals

n Active Low open-drain digital outputs
n 8-pin mini-SO plastic package

Key Specifications

j

Power Supply Voltage 2.8V–3.8V

j

Power Supply Current 1.5 mA (max)

j

LM88 Temperature Range −40˚C to +85˚C

j

Diode Setpoint Temperature

Range 0˚C to +125˚C

j

Temperature Trip PointAccuracy:

Diode Junction

Temperature

)

(T

DJ

+45˚C to +85˚C
+60˚C to +100˚C

Note: These are sample ranges. Contact factory for other

ranges.

LM88CIM
Accuracy

±

3˚C (max) −40˚C to +85˚C

±

3˚C (max) −40˚C to +85˚C

LM88CIM

Temperature

Range

Simplified Block Diagram and Connection Diagram

MSOP-8/MUA08A Package

Top View

10132601

© 2001 National Semiconductor Corporation DS101326 www.national.com

For simplicity, the effects of the hysteresis are not shown in the
temperature response diagram.

10132602

Simplified Block Diagram and Connection Diagram (Continued)

LM88

Order Number Device

Marking

LM88CIMM-A
LM88CIMMX-A Tape and

LM88CIMM-B
LM88CIMMX-B Tape and

For other setpoints please contact the factory. Performance is dependent on temperature range.

T08A

T08A

NS Package

Number

MUA08A

or

MSOP-8

MUA08A

or

MSOP-8

Transport

Media

Rail

Real

Rail

Real

T_SP0

(˚C)

61 49 80

41 49 60

Typical Application

T_SP1

(˚C)

T_CRIT

(˚C)

S etpoint

Accuracy

(˚C)

±

3

±

3

FIGURE 1. Thermal Protection for Pentium®Processor and Graphics Chip

10132613

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LM88

Absolute Maximum Ratings (Note 1)

Input Voltage 6V
Input Current at any pin (Note 2) 5mA
Package Input Current (Note 2) 20mA
Package Dissipation at T

(Note 4) 900mW

Soldering Information

MSOP Package (Note 6) :

= 25˚C

A

Operating Ratings(Note 1)

Operating Temperature
Range T

LM88CIMM −40˚C ≤ TA≤ +85˚C

Remote Diode Junction 0˚C ≤ T
Positive Supply Voltage (V
Maximum V

and V

O_CRIT,VO_SP0

O_SP1

+

) +2.8V to +3.8V

MIN

≤ T ≤ T

≤ +125˚C

DJ

Vapor Phase (60 seconds) 215˚C
Infrared (15 seconds) 220˚C

Storage Temperature −65˚C to + 150˚C
ESD Susceptibility (Note 5)

Human Body Model
Machine Model

2500V
250V

LM88 Electrical Characteristics

The following specifications apply for 2.8VDC≤V+≤ 3.8VDCunless otherwise specified. Boldface limits apply for TA=TJ=
T

to T

MIN

Symbol Parameter Conditions (Note 7) Limits (Limits)

Temperature Sensor

V

D−,VD0

I

D+SOURCE

V

D−Out

; all other limits TA=TJ= 25˚C unless otherwise specified.

MAX

Typical LM88CIMM Units

(Note 8)

Setpoint Temperature Accuracy (Note 9) +60˚C ≤ T

+45˚C ≤ T
+30˚C ≤ T

≤ +100˚C

DJ

≤ +85˚C

DJ

≤ +70˚C

DJ

±

3 ˚C (max)

Setpoint Hysteresis 1 ˚C (min)

1 ˚C (max)

Output Update Rate 920 ms (max)

and VD1Analog Inputs

Diode Source Current (D+ − D−)=0.65; high

level
(D+ − D−)=0.65; low

level

120 210 µA (max)

46 µA (min)

12 21 µA (max)

4.6 µA (min)

D− Output Source Voltage 0.7 V

MAX

+5.5V

LM88 Electrical Characteristics

The following specifications apply for 2.8VDC≤V+≤ 3.8VDCunless otherwise specified. Boldface limits apply for TA=TJ=
T

to T

MIN

Symbol Parameter Conditions Typical Limits Units

+

V

Power Supply

Digital Outputs

I

OUT(“1”)

V

OUT(“0”)

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed
specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test
conditions.

; all other limits TA=TJ= 25˚C unless otherwise specified.

MAX

I

S

Supply Current 1.5 mA (max)

Logical “1” Output Leakage
Current (Note 10)

V
where V

2.8V
V

2.8V

Logical “0” Output Voltage I

(Note 7) (Note 8) (Limits)

=V+− 0.6V

OUT

+

=3.8V to

=V+=3.8V to

OUT

=+3mA 0.4 V (max)

OUT

2 µA (max)

40 µA (max)

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