Rainbow Electronics LM82 User Manual

January 2000

LM82
Remote Diode and Local Digital Temperature Sensor
with Two-Wire Interface

LM82 Remote Diode and Local Digital Temperature Sensor with Two-Wire Interface

General Description

The LM82 is a digital temperature sensor with a 2 wire serial
interface thatsensesthe voltage and thus the temperature of
a remote diode using a Delta-Sigma analog-to-digital con­verter with a digital over-temperature detector.The LM82 ac­curately senses its own temperature as well as the tempera­ture of external devices, such as Pentium II
diode connected 2N3904s. The temperature of any ASIC
can be detected using the LM82 as long as a dedicated di­ode (semiconductor junction) is available on the die. Using
the SMBus interface a host can access the LM82’sregisters
at any time. Activation of a T_CRIT_A output occurs when
any temperature is greater than a programmable comparator
limit, T_CRIT. Activation of an INT output occurs when any
temperature is greater than its corresponding programmable
comparator HIGH limit.

The host can program as well as read back the state of the
T_CRIT register and the 2 T_HIGH registers. Three state
logic inputs allow two pins (ADD0, ADD1) to select up to 9
SMBus address locations for the LM82. The sensor powers
up with default thresholds of 127˚C for T_CRIT and all
T_HIGHs. The LM82 is pin for pin and register compatible
with the LM84, Maxim MAX1617 and Analog Devices
ADM1021.

®

Processors or

Features

n Accurately senses die temperature of remote ICs, or

diode junctions

n On-board local temperature sensing
n SMBus and I

SMBus 1.1 TIMEOUT

n Two interrupt outputs: INT and T_CRIT_A
n Register readback capability
n 7 bit plus sign temperature data format, 1 ˚C resolution
n 2 address select pins allow connection of 9 LM82s on a

single bus

2

C compatible interface, supports

Key Specifications

j

Supply Voltage 3.0V to 3.6V

j

Supply Current 0.8mA (max)

j

Local Temp Accuracy (includes quantization error)

0˚C to +85˚C

j

Remote Diode Temp Accuracy (includes quantization

error)

+25˚C to +100˚C

0˚C to +125˚C

±

3.0˚C (max)

±

3˚C (max)

±

4˚C (max)

Applications

n System Thermal Management
n Computers
n Electronic Test Equipment
n Office Electronics
n HVAC

Simplified Block Diagram

DS101297-1

SMBus™is a trademark of the Intel Corporation.

®

Pentium II

is a registered trademark of the Intel Corporation.

®

I2C

is a registered trademark of the Philips Corporation.

© 2000 National Semiconductor Corporation DS101297 www.national.com

Connection Diagram Ordering Information

LM82

QSOP-16

DS101297-2

TOP VIEW

Order

Number

LM82CIMQA

LM82CIMQAX

Typical Application

NS

Package

Number

MQA16A

(QSOP-16)

MQA16A

(QSOP-16)

Transport

Media

95 Units in

Rail

2500 Units on
Tape and
Reel

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DS101297-3

Pin Description

LM82

Label Pin

#

Function Typical Connection

floating, unconnected Left floating. PC board traces may be routed

NC 1, 5

V

CC

2

Positive Supply Voltage
Input

Diode Current Source To Diode Anode. Connected to remote discrete

D+ 3

D− 4

ADD0–ADD1 10, 6

Diode Return Current
Sink

User-Set SMBus (I

2

Address Inputs

C)

GND 7, 8 Power Supply Ground Ground

Manufacturing test pins. Left floating. PC board traces may be routed

NC 9, 13, 15

INT

11

SMBData 12

Interrupt Output,
open-drain

SMBus (I

2

C) Serial
Bi-Directional Data Line,
open-drain output

2

SMBCLK 14 SMBus (I

T_CRIT_A

16

Critical Temperature
Alarm, open-drain output

C) Clock Input From Controller, Pull-Up Resistor

through the pads for these pins. No restrictions
applied.

DC Voltage from 3.0 V to 3.6 V

diode junction or to the diode junction on a remote
IC whose die temperature is being sensed. When
not used they should be left floating.

To Diode Cathode. Must float when not used.

Ground (Low, “0”), VCC(High, “1”) or open
(“TRI-LEVEL”)

through the pads for these pins, although the
components that drive these traces should share
the same supply as the LM82 so that the Absolute
Maximum Rating, Voltage at Any Pin, is not
violated.

Pull Up Resistor, Controller Interrupt or Alert Line

From and to Controller, Pull-Up Resistor

Pull Up Resistor, Controller Interrupt Line or
System Shutdown

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Absolute Maximum Ratings (Note 1)

LM82

Supply Voltage −0.3 V to 6.0 V
Voltage at SMBData,

SMBCLK, T_CRIT_A & INT pins
Voltage at Other Pins −0.3 V to

D− Input Current
Input Current at All Other Pins (Note

2) 5 mA
Package Input Current (Note 2) 20 mA
SMBData, T_CRIT_A, INT Output

Sink Current 10 mA
Storage Temperature −65˚C to +150˚C

−0.5V to 6V

+ 0.3 V)

(V

CC

±

1mA

QSOP Package (Note 3)

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

ESD Susceptibility (Note 4)

Human Body Model 2000 V
Machine Model 250 V

Operating Ratings

(Notes 1, 5)
Specified Temperature Range T

LM82 −40˚C to +125˚C
Supply Voltage Range (V

) +3.0V to +3.6V

CC

Soldering Information, Lead Temperature

Temperature-to-Digital Converter Characteristics

Unless otherwise noted, these specifications apply for VCC=+3.0 Vdc to 3.6 Vdc. Boldface limits apply for TA=TJ=T
to T

Temperature Error using Local
Diode ((Note 8))

Temperature Error using Remote
Diode ((Note 8))

Resolution 8 Bits

Conversion Time of All
Temperatures

Quiescent Current (Note 9) SMBus (I
D− Source Voltage 0.7 V
Diode Source Current (D+ − D−)=+ 0.65V; high

T_CRIT_A and INT Output
Saturation Voltage

Power-On Reset Threshold On V

Local and Remote T_CRIT and
HIGH Default Temperature settings

; all other limits TA=TJ=+25˚C, unless otherwise noted.

MAX

Parameter Conditions Typical Limits Units

(Note 6) (Note 7) (Limit)

T

= 0 ˚C to +85˚C,

A

=+3.3V

V

CC

T

= −40 ˚C to +125˚C,

A

=+3.3V

V

CC

T

= +60 ˚C to +100˚C,

A

=+3.3V

V

CC

T

= 0 ˚C to +100˚C,

A

=+3.3V

V

CC

T

= 0 ˚C to +125˚C,

A

=+3.3V

V

CC

±

1

±

3 ˚C (max)

±

4 ˚C (max)

±

3

±

3 ˚C (max)

±

4 ˚C (max)

1˚C

(Note 10) 460 600 ms (max)

2

C) Inactive 0.500 0.80 mA (max)

125 µA (max)

level

60 µA (min)

Low level 15 µA (max)

5 µA (min)

I

= 3.0 mA 0.4

OUT

edge

input, falling

CC

2.3

1.8

(Note 11) +127 ˚C

to T

MIN

˚C (max)

V (max)
V (max)

V (min)

MAX

MIN

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Logic Electrical Characteristics

DIGITAL DC CHARACTERISTICS
Unless otherwise noted, these specifications apply for VCC=+3.0 to 3.6 Vdc. Boldface limits apply for TA=TJ=T
T

; all other limits TA=TJ=+25˚C, unless otherwise noted.

MAX

Symbol Parameter Conditions Typical Limits Units

(Note 6) (Note 7) (Limit)

SMBData, SMBCLK

V
V

IN(1)
IN(0)

V

IN(HYST)

Logical “1” Input Voltage 2.1 V (min)
Logical “0”Input Voltage 0.8 V (max)
SMBData and SMBCLK Digital

300 mV

Input Hysteresis
I
I

IN(1)
IN(0)

Logical “1” Input Current VIN=V

CC

0.005 1.5 µA (max)

Logical “0” Input Current VIN= 0 V −0.005 1.5 µA (max)

ADD0, ADD1

V
V
I
I

IN(1)

IN(0)
IN(1)
IN(0)

Logical “1” Input Voltage V

CC

1.5 V (min)
Logical “0”Input Voltage GND 0.6 V (max)
Logical “1” Input Current VIN=V

CC

2 µA (max)

Logical “0” Input Current VIN=0V -2 µA (max)

ALL DIGITAL INPUTS

C

IN

Input Capacitance 20 pF

ALL DIGITAL OUTPUTS

I

OH

V

OL

High Level Output Current VOH=V
SMBus Low Level Output

Voltage

IOL=3mA

=6mA

I

OL

CC

100 µA (max)

0.4

0.6

MIN

V (max)

LM82

to

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Logic Electrical Characteristics (Continued)

LM82

SMBus DIGITAL SWITCHING CHARACTERISTICS

Unless otherwise noted, these specifications apply for VCC=+3.0 Vdc to +3.6 Vdc, CL(load capacitance) on output lines = 80
pF. Boldface limits apply for T
The switching characteristics of the LM82 fully meet or exceed the published specifications of the SMBus or I2C bus. The fol­lowing parameters are the timing relationships between SMBCLK and SMBData signals related to the LM82. They are not the

2

I

C or SMBus bus specifications.

A=TJ=TMIN

to T

; all other limits TA=TJ= +25˚C, unless otherwise noted.

MAX

Symbol Parameter Conditions Typical Limits Units

(Note 6) (Note 7) (Limit)

f

SMB

SMBus Clock Frequency 100

10

t

LOW

SMBus Clock Low Time 10 % to 10 % 1.3

25

t

MEXT Cumulative Clock Low Extend Time 10 ms (max)

LOW

t

HIGH

t

R,SMB

t

F,SMB

t

OF

t

TIMEOUT

t

1

t

,

2

t

SU;DAT

t

,

3

t

HD;DAT

t

,

4

t

HD;STA

t

,

5

t

SU;STO

t

,

6

t

SU;STA

t

BUF

SMBus Clock High Time 90 % to 90% 0.6 µs (min)
SMBus Rise Time 10% to 90% 1 µs (max)
SMBus Fall Time 90% to 10% 0.3 ns (max)
Output Fall Time CL= 400 pF,

=3mA

I

O

SMBData and SMBCLK Time Low for
Reset of Serial Interface (Note 12)

250 ns (max)

25
40

SMBCLK (Clock) Period 10 µs (min)
Data In Setup Time to SMBCLK High 100 ns (min)

Data Out Stable after SMBCLK Low 300

TBD

SMBData Low Setup Time to SMBCLK

100 ns (min)

Low
SMBData High Delay Time after

100 ns (min)

SMBCLK High (Stop Condition Setup)
SMBus Start-Condition Setup Time 0.6 µs (min)

SMBus Free Time 1.3 µs (min)

kHz (max)

kHz (min)

µs (min)

ms (max)

ms (min)

ms (max)

ns (min)

ns (max)

SMBus Communication

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DS101297-4