Rainbow Electronics LM76 User Manual

January 2000

LM76

±

0.5˚C,±1˚C, 12-Bit + Sign Digital Temperature Sensor
and Thermal Window Comparator with Two-Wire
Interface

LM76

with Two-Wire Interface

±

0.5˚C,

±

1˚C, 12-Bit + Sign Digital Temperature Sensor and Thermal Window Comparator

General Description

The LM76 is a digital temperature sensor and thermal win­dow comparator with an I
accuracy of
fied for a −10˚C to 45˚C temperature range, while for the
LM76CNM the temperature range is 70˚C to 100˚C. The
LM76CHM isspecifiedwith an accuracy
window-comparator architecture of the LM76 eases the de­sign of temperature control systems conforming to the ACPI
(Advanced Configuration and Power Interface) specification
for personal computers. The open-drain Interrupt (INT) out­put becomes active whenever temperature goes outside a
programmable window, while a separate Critical Tempera­ture Alarm (T_CRIT_A) output becomes active when the
temperature exceeds a programmable critical limit. The INT
output can operate in either a comparator or event mode,
while the T_CRIT_A output operates in comparator mode
only.

The host can program both the upper and lower limits of the
window as well as the critical temperature limit. Program­mable hysterisis as well as a fault queue are available to
minimize false tripping. Two pins (A0, A1) are available for
address selection. The sensor powers up with default thresh­olds of 2˚C T
T_CRIT.

The LM76’s 3.3V and 5.0V supply voltage, Serial Bus inter­face, 12-bit + sign output, and full-scale range of over 127˚C
make it ideal for a wide range of applications. These include
thermal management and protection applications in personal
computers, electronic test equipment, office electronics and
bio-medical applications.

±

1˚C. This accuracy for the LM76CHM is speci-

HYST

2

C™Serial Bus interface with an

±

0.5˚C at 25˚C. The

, 10˚C T

LOW

, 64˚C T

HIGH

, and 80˚C

Features

n Window comparison simplifies design of ACPI

compatible temperature monitoring and control.

n Serial Bus interface
n Separate open-drain outputs for Interrupt and Critical

Temperature shutdown

n Shutdown mode to minimize power consumption
n Up to 4 LM76s can be connected to a single bus
n 12-bit + sign output; full-scale reading of over 127˚C

Key Specifications

j

Supply Voltage 3.3V or 5.0V

j

Supply Current operating 250 µA (typ)

450 µA (max)

shutdown 8 µA (max)

j

Temperature

Accuracy

−10˚C to +45˚C
70˚C to 100˚C

j

Resolution 0.0625˚C

+25˚C

±

0.5˚C(max)

±

1.0˚C(max)

±

1.0˚C(max)

Applications

n System Thermal Management
n Personal Computers
n Office Electronics
n HVAC

I2C®is a registered trademark of Philips Corporation.

© 2001 National Semiconductor Corporation DS101015 www.national.com

Simplified Block Diagram

LM76

Connection Diagram

DS101015-1

SO-8

DS101015-2

LM76 See NS Package Number M08A

Ordering Information

Temperature

Order Number Supply Voltage Acurracy

LM76CHM-5 5.0V

LM76CHMX-5 5.0V

LM76CNM-3 3.3V
LM76CNMX-3 3.3V

±

0.5˚C

±

1.0˚C

±

0.5˚C

±

1.0˚C

±

1˚C 70˚C to 100˚C 95 units in Rail

±

1˚C 70˚C to 100˚C 2500 Units on Tape and

Range for

Accuracy

25˚C

−10˚C to 45˚C
25˚C

−10˚C to 45˚C

Transport Media

95 units in Rail

2500 Units on Tape and
Reel

Reel

Pin Description

Label Pin

SDA 1 Serial Bi-Directional Data Line, Open Drain Output,

SCL 2 Serial Bus Clock Input, CMOS Logic Level From Controller I
T_CRIT_A 3 Critical Temperature Alarm, Open Drain Output Pull Up Resistor, Controller Interrupt Line

GND 4 Power Supply Ground Ground
INT 5 Interrupt, Open Drain Output Pull Up Resistor, Controller Interrupt Line
+V

S

A0–A1 7,6 User-Set Address Inputs, TTL Logic Level Ground (Low, “0”) or +V

#

CMOS Logic Level

8 Positive Supply Voltage Input DC Voltage from 3.3V power supply or

Function Typical Connection

Pull Up Resistor, Controller I

2

C Clock Line

or System Hardware Shutdown

5V.

2

(High, “1”)

S

C Data Line

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Pin Description (Continued)

LM76

DS101015-3

FIGURE 1. Typical Application

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Absolute Maximum Ratings (Note 1)

LM76

Supply Voltage −0.3V to 6.5V
Voltage at any Pin −0.3V to (+V
Input Current at any Pin 5mA
Package Input Current (Note 2) 20mA
T_CRIT_A and INT Output Sink

Current 10mA
T_CRIT_A and INT Output

+ 0.3V)

S

Soldering Information, Lead
Temperature

SOP Package (Note 3)

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

ESD Susceptibility (Note 4)

Human Body Model 3000V
Machine Model 250V

Voltage 6.5V
Storage Temperature −65˚C to +125˚C

Operating Ratings(Notes 1, 5)

Operating Temperature Range −55˚C to +150˚C
Specified Temperature Range

(Note 6) T

LM76CHM-5 −20˚C to +85˚C
LM76CNM-3 −55˚C to +125˚C

Supply Voltage Range (+V

)(Note 7) +3.0V to +5.5V

S

Temperature-to-Digital Converter Characteristics

Unless otherwise noted, these specifications apply for +VS=+3.3 Vdc±5% for the LM76CNM-3 and for +VS=+5.0 Vdc±10%
for the LM76CHM-5. (Note 7). Boldface limits apply for T

A=TJ=TMIN

wise noted.

Typical

Parameter Conditions

Accuracy (Note 7) T

= −25˚C to +125˚C for

A

(Note 8)

LM76CNM-3

= +70˚C to +100˚C

T

A

T

= −20˚C to +85˚C for

A

LM76CHM-5
T

= −10˚C to +45˚C

A

T

= +25˚C

A

Resolution (Note 10) 13

0.0625

Temperature Conversion

(Note 11) 400 500 1000 ms

Time
Quiescent Current I

2

C Inactive 0.25 mA

2

I

C Active 0.25 0.5 0.45 mA (max)

to T

±

2.5

±

1.5

; all other limits TA=TJ=+25˚C, unless other-

MAX

LM76CNM-3

Limits

(Note 9)

±

1.0

LM76CHM-5

Limits

(Note 9)

±

1.0

±

0.5

to T

MIN

Units

(Limit)

˚C (max)

Bits

˚C

MAX

Shutdown Mode: 5 µA

12 18 µA (max)

T

=+85˚C 8 µA (max)

A

T

=+25˚C 12 µA (max)

A

T

Default Temperature (Notes 13, 14) 2 ˚C

HYST

T

Default Temperature (Note 14) 10 ˚C

LOW

T

Default Temperature (Note 14) 64 ˚C

HIGH

T

Default Temperature (Note 14) 80 ˚C

CRIT

Logic Electrical Characteristics

DIGITAL DC CHARACTERISTICS Unless otherwise noted, these specifications apply for for +VS=+3.3 Vdc±5% for the

LM76CNM-3 and for +V
limits T

=+25˚C, unless otherwise noted.

A=TJ

Symbol Parameter Conditions

V

IN(1)

SDA and SCL Logical “1” Input
Voltage

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=+5.0 Vdc±10% for the LM76CHM-5. . Boldface limits apply for TA=TJ=T

S

Typical

(Note 8)

Limits

(Note 9)

+VSx 0.7 V (min)

+V

+0.3 V (max)

S

MIN

to T

MAX

; all other

Units

(Limit)

Logic Electrical Characteristics (Continued)

DIGITAL DC CHARACTERISTICS Unless otherwise noted, these specifications apply for for +VS=+3.3 Vdc±5% for the

LM76CNM-3 and for +V
limits T

=+25˚C, unless otherwise noted.

A=TJ

Symbol Parameter Conditions

V

IN(0)

SDA and SCL Logical “0” Input
Voltage

V

IN(HYST)

SDA and SCL Digital Input
Hysteresis

V

IN(1)

A0 and A1 Logical “1” Input
Voltage

V

IN(0)

A0 and A1 Logical “0” Input
Voltage

I
I
C
I
V

IN(1)
IN(0)

IN

OH

OL

Logical “1” Input Current VIN=+V
Logical “0” Input Current VIN= 0V −0.005 −1.0 µA (max)
Capacitance of All Digital Inputs 20 pF
High Level Output Current VOH=+V
Low Level Output Voltage IOL=3mA 0.4 V (max)
T_CRIT_A Output Saturation

Voltage
T_CRIT_A Delay 1 Conversions

t

OF

Output Fall Time CL= 400 pF 250 ns (max)

SERIAL BUS DIGITAL SWITCHING CHARACTERISTICS Unless otherwise noted, these specifications apply for +VS=+3.3

±

Vdc

5% for the LM76CNM-3 and for +VS=+5.0 Vdc±10% for the LM76CHM-5, CL (load capacitance) on output lines = 80
pF unless otherwise specified. Boldface limits apply for T
wise noted.
The switching characteristics of the LM76 fully meet or exceed the published specifications of the I
rameters are the timing relationship between SCL and SDA signal related to the LM76. They are not the I

Symbol Parameter Conditions

t

1

t

2

t

3

t

4

t

5

SCL (Clock) Period 2.5 µs(min)
Data in Set-Up Time to SCL High 100 ns(min)
Data Out Stable after SCL Low 0 ns(min)
SDA Low Set-Up Time to SCL Low (Start Condition) 100 ns(min)
SDA High Hold Time after SCL High (Stop Condition) 100 ns(min)

=+5.0 Vdc±10% for the LM76CHM-5. . Boldface limits apply for TA=TJ=T

S

Typical

(Note 8)

Limits

(Note 9)

−0.3 V (min)

+V

x 0.3 V (max)

S

500 250 mV (min)

2.0 V (min)

+V

+0.3 V (max)

S

−0.3 V (min)

0.8 V (max)

0.005 1.0 µA (max)

10 µA (max)

0.8 V (max)

I

OUT

S

S

= 4.0 mA

(Note 12)

I

=3mA

O

to T

A=TJ=TMIN

; all other limits TA=TJ= +25˚C, unless other-

MAX

2

C bus. The following pa-

Typical

(Note 8)

MIN

to T

MAX

; all other

Units

(Limit)

(max)

2

C bus specifications.

Limits

(Note 9)

LM76

Units

(Limit)

DS101015-4

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