LM83_技术文档

November 1999

LM83

Triple-Diode Input and Local Digital Temperature Sensor

with Two-Wire Interface

n On-board local temperature sensing

General Description

n SMBus and I²C compatible interface, supports

The LM83 is a digital temperature sensor with a 2 wire serial

SMBus 1.1 TIMEOUT

interface that senses the voltage and thus the temperature of

n Two interrupt outputs: INT and T_CRIT_A

three remote diodes using a Delta-Sigma analog-to-digital

converter with a digital over-temperature detector. The LM83

accurately senses its own temperature as well as the tem-

n Register readback capability

n 7 bit plus sign temperature data format, 1 ˚C resolution

perature of three external devices, such as Pentium II^®Pro-

cessors or diode connected 2N3904s. The temperature of

any ASIC can be detected using the LM83 as long as a dedi-

cated diode (semiconductor junction) is available on the die.

Using the SMBus interface a host can access the LM83’s

registers at any time. Activation of a T_CRIT_A output oc-

curs 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 pro-

grammable comparator HIGH limit.

n 2 address select pins allow connection of 9 LM83s on a

single bus

Key Specifications

j

Supply Voltage

Supply Current

3.0V to 3.6V

0.8mA (max)

Local Temp Accuracy (includes quantization error)

±

0˚C to +85˚C

3.0˚C (max)

j

Remote Diode Temp Accuracy (includes quantization

The host can program as well as read back the state of the

T_CRIT register and the four T_HIGH registers. Three state

logic inputs allow two pins (ADD0, ADD1) to select up to 9

SMBus address locations for the LM83. The sensor powers

up with default thresholds of 127˚C for T_CRIT and all

T_HIGHs. The LM83 is pin for pin and register compatible

with the LM84 as well as the Maxim MAX1617 and the Ana-

log Devices ADM1021.

error)

±

+25˚C to +100˚C

0˚C to +125˚C

3˚C (max)

4˚C (max)

Applications

n System Thermal Management

n Computers

Features

n Electronic Test Equipment

n Office Electronics

n HVAC

n Accurately senses die temperature of 3 remote ICs, or

diode junctions

Simplified Block Diagram

DS101058-1

™

SMBus is a trademark of the Intel Corporation.

Pentium II^®is a registered trademark of the Intel Corporation.

2

I

C^®is a registered trademark of the Philips Corporation.

DS101058

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Connection Diagram

Ordering Information

NS

Order

QSOP-16

Transport

Media

Package

Number

MQA16A

LM83CIMQA

95 Units in

Rail

(QSOP-16)

2500 Units on

Tape and

Reel

MQA16A

LM83CIMQAX

(QSOP-16)

DS101058-2

TOP VIEW

Typical Application

DS101058-3

Pin Description

#

Label

Function

Typical Connection

Diode Current Source

To Diode Anode. Connected to remote discrete

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.

D1+, D2+, D3+

1, 3, 5

2

Positive Supply Voltage

Input

DC Voltage from 3.0 V to 3.6 V

V_CC

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2

Pin Description (Continued)

#

Label

Function

Typical Connection

Diode Return Current

Sink

To all Diode Junction Cathodes using a star

connection to pin. Must float when not used.

D−

4

User-Set SMBus (I²C)

Address Inputs

Ground (Low, “0”), V_CC(High, “1”) or open

(“TRI-LEVEL”)

ADD0–ADD1

GND

10, 6

7, 8

Power Supply Ground

Manufacturing test pins.

Ground

Left floating. PC board traces may be routed

through the pads for these pins, although the

components that drive these traces should share

the same supply as the LM83 so that the Absolute

Maximum Rating, Voltage at Any Pin, is not

violated.

NC

9, 13, 15

Interrupt Output,

open-drain

SMBus (I²C) Serial

Bi-Directional Data Line,

open-drain output

Pull Up Resistor, Controller Interrupt or Alert Line

INT

11

12

From and to Controller, Pull-Up Resistor

SMBData

SMBCLK

14

16

SMBus (I²C) Clock Input

From Controller, Pull-Up Resistor

Critical Temperature

Alarm, open-drain output

Pull Up Resistor, Controller Interrupt Line or

System Shutdown

T_CRIT_A

3

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Absolute Maximum Ratings (Note 1)

QSOP Package (Note 3)

Vapor Phase (60 seconds)

Infrared (15 seconds)

ESD Susceptibility (Note 4)

Human Body Model

215˚C

220˚C

Supply Voltage

−0.3 V to 6.0 V

Voltage at Any Pin

−0.3 V to

(V_CC+ 0.3 V)

2000 V

200 V

±

D− Input Current

1 mA

Machine Model

Input Current at All Other Pins (Note

2)

5 mA

Operating Ratings

(Notes 1, 5)

Package Input Current (Note 2)

20 mA

10 mA

SMBData, T_CRIT_A, INT Output

Sink Current

Specified Temperature Range

LM83

T_MINto T_MAX

−40˚C to +125˚C

+3.0V to +3.6V

SMBCLK, SMBData, T_CRIT_A, INT

Output Voltage

6.0 V

Storage Temperature

−65˚C to +150˚C

Supply Voltage Range (V_CC)

Soldering Information, Lead Temperature

Temperature-to-Digital Converter Characteristics

Unless otherwise noted, these specifications apply for V_CC=+3.0Vdc to 3.6Vdc. Boldface limits apply for T_A= T_J= T_MINto

T_MAX; all other limits T_A= T_J=+25˚C, unless otherwise noted.

Parameter

Conditions

Typical

Limits

Units

(Limit)

(Note 6)

(Note 7)

±

Temperature Error using Local

Diode ((Note 8))

T_A= 0 ˚C to +85˚C,

V_CC=+3.3V

1

3

4

3

4

˚C (max)

T_A= −40 ˚C to +125˚C,

V_CC=+3.3V

˚C (max)

Temperature Error using Remote

Diode ((Note 8))

T_A= +60 ˚C to +100˚C,

V_CC=+3.3V

˚C (max)

T_A= 25 ˚C to +100˚C,

V_CC=+3.3V

T_A= 0 ˚C to +125˚C,

V_CC=+3.3V

˚C (max)

Diode Channel to Channel Matching

Resolution

0

˚C

Bits

8

1

˚C

Conversion Time of All

Temperatures

(Note 10)

460

600

ms (max)

Quiescent Current (Note 9)

D− Source Voltage

SMBus (I²C) Inactive

0.500

0.7

0.80

mA (max)

V

Diode Source Current

(D+ − D−)=+ 0.65V; high

level

125

60

15

5

µA (max)

µA (min)

µA (max)

µA (min)

Low level

T_CRIT_A and INT Output

Saturation Voltage

I_OUT= 3.0 mA

0.4

V (max)

Power-On Reset Threshold

On V_CCinput, falling

edge

2.3

1.8

V (max)

V (min)

Local and Remote T_CRIT and

(Note 11)

+127

˚C

HIGH Default Temperature settings

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4

Logic Electrical Characteristics

DIGITAL DC CHARACTERISTICS

Unless otherwise noted, these specifications apply for V_CC=+3.0 to 3.6 Vdc. Boldface limits apply for T_A= T_J= T_MINto

T_MAX; all other limits T_A= T_J=+25˚C, unless otherwise noted.

Symbol

Parameter

Conditions

Typical

Limits

Units

(Note 6)

(Note 7)

(Limit)

SMBData, SMBCLK

V_IN(1)

V_IN(0)

Logical “1” Input Voltage

Logical “0”Input Voltage

2.1

0.8

V (min)

V (max)

mV

V_IN(HYST)

SMBData and SMBCLK Digital

Input Hysteresis

300

I_IN(1)

Logical “1” Input Current

Logical “0” Input Current

V_IN= V_CC

0.005

1.5

µA (max)

I_IN(0)

V_IN= 0 V

−0.005

ADD0, ADD1

V_IN(1)

Logical “1” Input Voltage

Logical “0”Input Voltage

Logical “1” Input Current

Logical “0” Input Current

V_CC

1.5

0.6

2

V (min)

V (max)

µA (max)

V_IN(0)

GND

I_IN(1)

V_IN= V_CC

V_IN= 0 V

I_IN(0)

-2

ALL DIGITAL INPUTS

C_IN

Input Capacitance

20

pF

ALL DIGITAL OUTPUTS

I_OH

High Level Output Current

V_OH= V_CC

100

µA (max)

V (max)

V_OL

SMBus Low Level Output

Voltage

I_OL= 3 mA

I_OL= 6 mA

0.4

0.6

5

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Logic Electrical Characteristics (Continued)

SMBus DIGITAL SWITCHING CHARACTERISTICS

Unless otherwise noted, these specifications apply for V_CC=+3.0 Vdc to +3.6 Vdc, C_L(load capacitance) on output lines = 80

pF. Boldface limits apply for T_A= T_J= T_MINto T_MAX; all other limits T_A= T_J= +25˚C, unless otherwise noted.

The switching characteristics of the LM83 fully meet or exceed the published specifications of the SMBus or I²C bus. The fol-

lowing parameters are the timing relationships between SMBCLK and SMBData signals related to the LM83. They are not the

I²C or SMBus bus specifications.

Symbol

Parameter

Conditions

Typical

Limits

Units

(Note 6)

(Note 7)

(Limit)

f_SMB

t_LOW

SMBus Clock Frequency

SMBus Clock Low Time

100

10

kHz (max)

kHz (min)

10 % to 10 %

1.3

25

µs (min)

ms (max)

t

_LOWMEXT Cumulative Clock Low Extend Time

10

ms (max)

µs (min)

µs (max)

ns (max)

t_HIGH

t_R,SMB

t_F,SMB

t_OF

SMBus Clock High Time

SMBus Rise Time

SMBus Fall Time

90 % to 90%

10% to 90%

90% to 10%

0.6

1

0.3

Output Fall Time

C_L= 400 pF,

I_O= 3 mA

250

t_TIMEOUT

SMBData and SMBCLK Time Low for

Reset of Serial Interface (Note 12)

25

40

ms (min)

ms (max)

t₁

SMBCLK (Clock) Period

10

µs (min)

ns (min)

t₂,

Data In Setup Time to SMBCLK High

100

t_SU;DAT

t₃,

t_HD;DAT

Data Out Stable after SMBCLK Low

300

TBD

ns (min)

ns (max)

t₄,

t_HD;STA

SMBData Low Setup Time to SMBCLK

Low

100

0.6

1.3

ns (min)

µs (min)

t₅,

t_SU;STO

SMBData High Delay Time after

SMBCLK High (Stop Condition Setup)

t₆,

t_SU;STA

SMBus Start-Condition Setup Time

SMBus Free Time

t_BUF

SMBus Communication

DS101058-4

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6

Logic Electrical Characteristics (Continued)

SMBus TIMEOUT

DS101058-7

See drawing DS10105807

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating

the device beyond its rated operating conditions.

<

>

V

Note 2: When the input voltage (V ) at any pin exceeds the power supplies (V

GND or V

), the current at that pin should be limited to 5 mA. The 20 mA

CC

I

maximum package input current rating limits the number of pins that can safely exceed the power supplies with an input current of 5 mA to four.

Parasitic components and or ESD protection circuitry are shown in the figure below for the LM83’s pins. The nominal breakdown voltage of the zener D3 is 6.5 V.

Care should be taken not to forward bias the parasitic diode, D1, present on pins: D+, D−, ADD1 and ADD0. Doing so by more than 50 mV may corrupt a temperature

or voltage measurement.

Pin Name

D1

D2

D3

D4

Pin Name

T_CRIT_A & INT

SMBData

D1

D2

x

D3

D4

V_CC

D+

x

NC (pins 9 & 15)

SMBCLK

x

D−

x

ADD0, ADD1

NC (pin 13)

x

Note: An x indicates that the diode exists.

DS101058-13

FIGURE 1. ESD Protection Input Structure

Note 3: See AN-450 “Surface Mounting Methods and Their Effect on Product Reliability” or the section titled “Surface Mount” found in a current National Semicon-

ductor Linear Data Book for other methods of soldering surface mount devices.

Note 4: Human body model, 100 pF discharged through a 1.5 kΩ resistor. Machine model, 200 pF discharged directly into each pin.

Note 5: Thermal resistance of the QSOP-16 package is xyz˚C/W, junction-to-ambient when attached to a printed circuit board with 2 oz. foil as shown in Figure 3

.

7

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Logic Electrical Characteristics (Continued)

Note 6: Typicals are at T = 25˚C and represent most likely parametric norm.

A

Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).

±

Note 8: The Temperature Error will vary less than 1.0 ˚C for a variation in V

of 3 V to 3.6 V from the nominal of 3.3 V.

CC

Note 9: Quiescent current will not increase substantially with an active SMBus.

Note 10: This specification is provided only to indicate how often temperature data is updated. The LM83 can be read at any time without regard to conversion state

(and will yield last conversion result).

Note 11: Default values set at power up.

Note 12: Holding the SMBData and/or SMBCLK lines Low for a time interval greater than t

will cause the LM83 to reset SMBData and SMBCLK to the IDLE

TIMEOUT

state of an SMBus communication (SMBCLK and SMBData set High).

DS101058-5

FIGURE 2. Temperature-to-Digital Transfer Function (Non-linear scale for clarity)

DS101058-24

FIGURE 3. Printed Circuit Board Used for Thermal Resistance Specifications

1.0 Functional Description

The LM83 temperature sensor incorporates a band-gap type

temperature sensor using a Local or three Remote diodes

and an 8-bit ADC (Delta-Sigma Analog-to-Digital Converter).

The LM83 is compatible with the serial SMBus and I²C two

wire interfaces. Digital comparators compare Local (LT) and

Remote (D1RT, D2RT and D3RT) temperature readings to

user-programmable setpoints (LHS, D1RHS, D2RHS,

D3RHS and TCS). Activation of the INT output indicates that

a comparison is greater than the limit preset in a HIGH reg-

ister. The T_CRIT setpoint (TCS) interacts with all the tem-

perature readings. Activation of the T_CRIT_A output indi-

cates that any or all of the temperature readings have

exceed the T_CRIT setpoint.

1. Remote Diode 2 (D2RT)

2. Remote Diode 1 (D1RT)

3. Remote Diode 3 (D3RT)

This round robin sequence takes approximately 480 ms to

complete as each temperature is digitized in approximately

120 ms.

1.2 INT OUTPUT and T_HIGH LIMITS

Each temperature reading (LT, D1RT, D2RT, and D3RT) is

associated with a T_HIGH setpoint register (LHS, D1RHS,

D2RHS, D3RHS). At the end of a temperature reading a digi-

tal comparison determines whether that reading has exceed

its HIGH setpoint. If the temperature reading is greater than

the HIGH setpoint, a bit is set in one of the Status Registers,

to indicate which temperature reading, and the INT output is

activated.

1.1 CONVERSION SEQUENCE

The LM83 converts its own temperature as well as 3 remote

diode temperatures in the following sequence:

Local and remote temperature diodes are sampled in se-

quence by the A/D converter. The INT output and the Status

1. Local Temperature (LT)

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8

Local and remote temperature diodes are sampled in se-

quence by the A/D converter. The T_CRIT_A output and the

Status Register flags are updated at the completion of a con-

version. T_CRIT_A and the Status Register flags are reset

only after the Status Register is read and if a temperature

conversion is below the T_CRIT setpoint, as shown in Figure

1.0 Functional Description (Continued)

Register flags are updated at the completion of a conversion,

which occurs approximately 60 ms after a temperature diode

is sampled. INT is deactivated when the Status Register,

containing the set bit, is read and a temperature reading is

less than or equal to it’s corresponding HIGH setpoint, as

shown in Figure 4. Figure 5shows a simplified logic diagram

for the INT output and related circuitry.

6. Figure

7 shows a simplified logic diagram of the

T_CRIT_A and related circuitry.

DS101058-6

*

Note: Status Register Bits are reset by a read of Status Register where

bit is located.

FIGURE 6. T_CRIT_A Temperature Response Diagram

with remote diode 1 and local temperature masked.

DS101058-14

*

Note: Status Register Bits are reset by a read of Status Register where

bit is located.

FIGURE 4. INT Temperature Response Diagram with

D2RHS and D3RHS set to 127˚C.

DS101058-21

DS101058-20

FIGURE 5. INT output related circuitry logic diagram

FIGURE 7. T_CRIT_A output related circuitry logic

diagram

The INT output can be disabled by setting the INT mask bit,

D7, of the configuration register. INT can be programmed to

be active high or low by the state of the INT inversion bit, D1,

in the configuration register. A “0” would program INT to be

active low. INT is an open-drain output.

Located in the Configuration Register are the mask bits for

each temperature reading, seeSection 2.5. When a mask bit

is set, its corresponding status flag will not propagate to the

T_CRIT_A output, but will still be set in the Status Registers.

Setting all four mask bits or programming the T_CRIT set-

point to 127˚C will disable the T_CRIT_A output.

1.3 T_CRIT_A OUTPUT and T_CRIT LIMIT

T_CRIT_A is activated when any temperature reading is

greater than the limit preset in the critical temperature set-

point register (T_CRIT), as shown in Figure 6. The Status

Registers can be read to determine which event caused the

alarm. A bit in the Status Registers is set high to indicate

which temperature reading exceeded the T_CRIT setpoint

temperature and caused the alarm, see Section 2.3.

1.4 POWER ON RESET DEFAULT STATES

LM83 always powers up to these known default states:

1. Command Register set to 00h

2. Local Temperature set to 0˚C

9

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1.6 TEMPERATURE DATA FORMAT

1.0 Functional Description (Continued)

Temperature data can be read from the Local and Remote

Temperature, T_CRIT, and HIGH setpoint registers; and writ-

ten to the T_CRIT and HIGH setpoint registers. Temperature

data is represented by an 8-bit, two’s complement byte with

an LSB (Least Significant Bit) equal to 1˚C:

3. Diode 1, Diode 2, and Diode 3 Remote Temperature set

to 0˚C until the LM83 senses a diode present between

the D+ and D− input pins.

4. Status Registers 1 and 2 set to 00h.

5. Configuration Register set to 00h; INT enabled and all

T_CRIT setpoints enabled to activate T_CRIT_A.

Temperature

Digital Output

Binary

Hex

7Dh

19h

01h

00h

FFh

E7h

C9h

6. Local and all Remote T_CRIT set to 127˚C

+125˚C

+25˚C

+1˚C

0111 1101

0001 1001

0000 0001

0000 0000

1111 1111

1110 0111

1100 1001

1.5 SMBus INTERFACE

The LM83 operates as a slave on the SMBus, so the

SMBCLK line is an input (no clock is generated by the LM83)

and the SMBData line is bi-directional. According to SMBus

specifications, the LM83 has a 7-bit slave address. Bit 4 (A3)

of the slave address is hard wired inside the LM83 to a 1.

The remainder of the address bits are controlled by the state

of the address select pins ADD1 and ADD0, and are set by

connecting these pins to ground for a low, (0) , to V_CCfor a

high, (1), or left floating (TRI-LEVEL).

0˚C

−1˚C

−25˚C

−55˚C

1.7 OPEN-DRAIN OUTPUTS

The SMBData, INT and T_CRIT_A outputs are open-drain

outputs and do not have internal pull-ups. A “high” level will

not be observed on these pins until pull-up current is pro-

vided from some external source, typically a pull-up resistor.

Choice of resistor value depends on many system factors

but, in general, the pull-up resistor should be as large as

possible. This will minimize any internal temperature reading

errors due to internal heating of the LM83. The maximum re-

sistance of the pull up, based on LM83 specification for High

Level Output Current, to provide a 2.1V high level, is 30kΩ.

Therefore, the complete slave address is:

A6

A5

A4

1

A2

A1

A0

MSB

LSB

and is selected as follows:

Address Select Pin State

LM83 SMBus

Slave Address

A6:A0 binary

001 1000

ADD0

ADD1

0

1.8 DIODE FAULT DETECTION

0

TRI-LEVEL

001 1001

Before each external conversion the LM83 goes through an

external diode fault detection sequence. If a D+ input is

shorted to V_CCor floating then the temperature reading will

be +127 ˚C, and its OPEN bit in the Status Register will be

set. If the T_CRIT setpoint is set to less than +127 ˚C then

the D+ inputs RTCRIT bit in the Status Register will be set

which will activate the T_CRIT_A output, if enabled. If a D+

is shorted to GND or D−, its temperature reading will be 0 ˚C

and its OPEN bit in the Status Register will not be set.

0

1

001 1010

TRI-LEVEL

0

010 1001

TRI-LEVEL

010 1010

TRI-LEVEL

1

010 1011

1

0

100 1100

TRI-LEVEL

1

100 1101

100 1110

The LM83 latches the state of the address select pins during

the first read or write on the SMBus. Changing the state of

the address select pins after the first read or write to any de-

vice on the SMBus will not change the slave address of the

LM83.

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1.0 Functional Description (Continued)

1.9 COMMUNICATING with the LM83

DS101058-9

There are 19 data registers in the LM83, selected by the

Command Register. At power-up the Command Register is

set to “00”, the location for the Read Local Temperature Reg-

ister. The Command Register latches the last location it was

set to. Reading the Status Register resets T_CRIT_A and

INT, so long as a temperature comparison does not signal a

fault (see Sections 1.2 and 1.3). All other registers are pre-

defined as read only or write only. Read and write registers

with the same function contain mirrored data.

isters because that will be the data most frequently read

from the LM83), then the read can simply consist of an

address byte, followed by retrieving the data byte.

2. If the Command Register needs to be set, then an ad-

dress byte, command byte, repeat start, and another ad-

dress byte will accomplish a read.

The data byte has the most significant bit first. At the end of

a read, the LM83 can accept either Acknowledge or No Ac-

knowledge from the Master (No Acknowledge is typically

used as a signal for the slave that the Master has read its

last byte).

A Write to the LM83 will always include the address byte and

the command byte. A write to any register requires one data

byte.

1.10 SERIAL INTERFACE ERROR RECOVERY

Reading the LM83 can take place either of two ways:

The LM83 SMBus lines will be reset to the SMBus idle state

if the SMBData or SMBCLK lines are held low for 40 ms or

more (t_TIMEOUT). The LM83 may or may not reset the state of

1. If the location latched in the Command Register is cor-

rect (most of the time it is expected that the Command

Register will point to one of the Read Temperature Reg-

11

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1.0 Functional Description (Continued)

the serial interface logic if either of the SMBData or SMBCLK

lines are held low between 25 ms and 40 ms. TIMEOUT al-

lows a clean recovery in cases where the master may be re-

set while the LM83 is transmitting a low bit thus preventing

possible bus lock up.

Whenever the LM83 sees the start condition its serial inter-

face will reset to the beginning of the communication, thus

the LM83 will expect to see an address byte next. This sim-

plifies recovery when the master is reset while the LM83 is

transmitting a high.

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12

1.0 Functional Description (Continued)

2.0 LM83 REGISTERS

2.1 COMMAND REGISTER

Selects which registers will be read from or written to. Data for this register should be transmitted during the Command Byte of

the SMBus write communication.

P7

P6

P5

P4

P3

P2

P1

P0

0

Command Select

P0-P7: Command Select

Command Se-

lect Address

Power On Default State

Register Name

Register Function

<

>

<

>

<

>

P7:P0 hex

D7:D0 binary

D7:D0 deci-

mal

0

00h

01h

0000 0000

RLT

Read Local Temperature

0

RD2RT

Read D2 Remote

Temperature

02h

03h

04h

05h

06h

07h

0000 0000

0111 1111

0

RSR1

RC

Read Status Register 1

Read Configuration

Reserved

0

127

RLHS

Read Local HIGH Setpoint

Reserved

0111 1111

127

RD2RHS

Read D2 Remote HIGH

Setpoint

08h

09h

0Ah

0Bh

0Ch

0Dh

Reserved

0000 0000

0111 1111

WC

Write Configuration

Reserved

127

WD2LHS

WD2RHS

Write Local HIGH Setpoint

Reserved

Write D2 Remote HIGH

Setpoint

0Eh-2Fh

30h

Reserved for Future Use

0000 0000

0

RD1RT

RD3RT

Read D1 Remote

Temperature

31h

Read D3 Remote

Temperature

32h-34h

35h

Reserved for Future Use

Read Status Register 2

Reserved for Future Use

0000 0000

0111 1111

0

RSR2

36h-37h

38h

127

RD1RHS

Read D1 Remote HIGH

Setpoint

39h

3Ah

Reserved for Future Use

0111 1111

127

RD3RHS

Read D3 Remote HIGH

Setpoint

3Bh-41h

42h

Reserved for Future Use

Read T_CRIT Setpoint

Reserved for Future Use

0111 1111

127

RTCS

43h-4Fh

50h

WD1RHS

Write D1 Remote HIGH

Setpoint

51h

52h

Reserved for Future Use

0111 1111

127

WD3RHS

Write D3 Remote HIGH

Setpoint

53h-59h

5Ah

Reserved for Future Use

Write T_CRIT Setpoint

WTCS

13

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1.0 Functional Description (Continued)

Command Se-

lect Address

Power On Default State

Register Name

Register Function

<

>

<

>

<

>

P7:P0 hex

D7:D0 binary

D7:D0 deci-

mal

5Ch-6Fh and

F0h-FDh

Reserved for Future Use

Read Manufacturers ID

FEh

FFh

0000 0001

1

RMID

RSR

Read Stepping or Die

Revision Code

2.2 LOCAL and D1, D2 and D3 REMOTE TEMPERATURE REGISTERS (LT, D1RT, D2RT, and D3RT)

(Read Only Address 00h, 01h, 30h and 31h):

D7

D6

D5

D4

D3

D2

D1

D0

MSB

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

LSB

D7–D0: Temperature Data. One LSB = 1˚C. Two’s complement format.

2.3 STATUS REGISTERS 1 and 2

2.3.1 Status Register 1 (SR1) (Read Only Address 02h):

D7

D6

D5

D4

D3

D2

D1

D0

0

LHIGH

0

D2RHIGH

0

D2OPEN

D2CRIT

LCRIT

Power up default is with all bits “0” (zero).

D0: LCRIT: When set to a 1 indicates an Local Critical Temperature alarm.

D1: D2CRIT: When set to a 1 indicates a Remote Diode 2 Critical Temperature alarm.

D2: D2OPEN: When set to 1 indicates a Remote Diode 2 disconnect.

D4: D2RHIGH: When set to 1 indicates a Remote Diode 2 HIGH Temperature alarm.

D6: LHIGH: When set to 1 indicates a Local HIGH Temperature alarm.

D7, D5, and D3: These bits are always set to 0 and reserved for future use.

Status Register 2

2.3.2 Status Register 2 (SR2) (Read Only Address 35h):

D7

D6

D5

D4

D3

D2

D1

D0

D1RHIGH

0

D1OPEN D3RHIGH

0

D3OPEN

D3CRIT

D1CRIT

Power up default is with all bits “0” (zero).

D0: D1CRIT, when set to 1 indicates a Remote Diode 1 Critical Temperature alarm.

D1: D3CRIT, when set to 1 indicates a Remote Diode 3 Critical Temperature alarm.

D2: D3OPEN, when set to 1 indicates a Remote Diode 3 disconnect.

D4: D3RHIGH, when set to 1 indicates a Remote Diode 3 HIGH Temperature alarm.

D5: D1OPEN, when set to 1 indicates a Remote Diode 1 disconnect.

D7: D1RHIGH, when set to 1 indicates a Remote Diode 1

HIGH Temperature alarm.

D6, and D3: These bits are always set to 0 and reserved for future use.

2.4 MANUFACTURERS ID REGISTER

(Read Address FEh) Default value 01h.

2.5 CONFIGURATION REGISTER

(Read Address 03h/Write Address 09h):

D7

D6

D5

D4

D3

D2

D1

INT Inversion

D0

INT mask

0

D1

T_CRIT_A

mask

D2

T_CRIT_A

mask

D3

T_CRIT_A

mask

Local

T_CRIT_A

mask

0

Power up default is with all bits “0” (zero).

D7: INT mask: When set to 1 INT interrupts are masked.

www.national.com

14

1.0 Functional Description (Continued)

D5: T_CRIT mask for Diode 1, when set to 1 a Diode 1 temperature reading that exceeds T_CRIT setpoint will not activate the

T_CRIT_A pin.

D4: T_CRIT mask for Diode 2, when set to 1 a Diode 2 temperature reading that exceeds T_CRIT setpoint will not activate the

T_CRIT_A pin.

D3: T_CRIT mask for Diode 3, when set to 1 a Diode 3 temperature reading that exceeds T_CRIT setpoint will not activate the

T_CRIT_A pin.

D2: T_CRIT mask for Local reading, when set to 1 a Local temperature reading that exceeds T_CRIT setpoint will not activate

the T_CRIT_A pin.

D1: INT active state inversion. When INT Inversion is set to a 1 the active state of the INT output will be a logical high. A low would

then select an active state of a logical low.

D6 and D0: These bits are always set to 0 and reserved for future use. A write of 1 will return a 0 when read.

2.6 LOCAL, DIODE 1, DIODE 2 and DIODE 3 HIGH SETPOINT REGISTERS (LHS, D1RHS, D2RHS and D3RHS)

(Read Address 05h, 07h, 38h, 3Ah /Write Address 0Bh, 0Dh,

50h, 52h):

D7

D6

D5

D4

D3

D2

D1

D0

MSB

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

LSB

D7–D0: HIGH setpoint temperature data. Power up default is LHIGH = RD1HIGH=RD2HIGH=RD3HIGH = 127˚C.

2.7 T_CRIT REGISTER (TCS)

(Read Address 42h/Write Address 5Ah):

D7

D6

D5

D4

D3

D2

D1

D0

MSB

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

LSB

D7–D0: T_CRIT setpoint temperature data. Power up default is T_CRIT = 127˚C.

15

www.national.com

3.0 SMBus Timing Diagrams

DS101058-10

(a) Serial Bus Write to the internal Command Register followed by a the Data Byte

DS101058-11

(b) Serial Bus Write to the internal Command Register

DS101058-12

(c) Serial Bus Read from a Register with the internal Command Register preset to desired value.

FIGURE 8. Serial Bus Timing Diagrams

www.national.com

16

4.0 Application Hints

The LM83 can be applied easily in the same way as other

integrated-circuit temperature sensors, and its remote diode

sensing capability allows it to be used in new ways as well.

It can be soldered to a printed circuit board, and because the

path of best thermal conductivity is between the die and the

pins, its temperature will effectively be that of the printed cir-

cuit board lands and traces soldered to the LM83’s pins. This

presumes that the ambient air temperature is almost the

same as the surface temperature of the printed circuit board;

if the air temperature is much higher or lower than the sur-

face temperature, the actual temperature of the of the LM83

die will be at an intermediate temperature between the sur-

face and air temperatures. Again, the primary thermal con-

duction path is through the leads, so the circuit board tem-

perature will contribute to the die temperature much more

strongly than will the air temperature.

where:

•

η is the non-ideality factor of the process the diode is

manufactured on,

•

q is the electron charge,

k is the Boltzmann’s constant,

N is the current ratio,

T is the absolute temperature in ˚K.

The temperature sensor then measures ∆V_BEand converts

to digital data. In this equation, k and q are well defined uni-

versal constants, and N is a parameter controlled by the tem-

perature sensor. The only other parameter is η, which de-

pends on the diode that is used for measurement. Since

∆V_BEis proportional to both η and T, the variations in η can-

not be distinguished from variations in temperature. Since

the non-ideality factor is not controlled by the temperature

sensor, it will directly add to the inaccuracy of the sensor. For

the Pentium II Intel specifies a 1% variation in η from part

to part. As an example, assume a temperature sensor has

an accuracy specification of 3 ˚C at room temperature of 25

˚C and the process used to manufacture the diode has a

To measure temperature external to the LM83’s die, use a

remote diode. This diode can be located on the die of a tar-

get IC, allowing measurement of the IC’s temperature, inde-

pendent of the LM83’s temperature. The LM83 has been op-

timized to measure the remote diode of a Pentium II

processor as shown in Figure 9. A discrete diode can also be

used to sense the temperature of external objects or ambient

air. Remember that a discrete diode’s temperature will be af-

fected, and often dominated, by the temperature of its leads.

±

non-ideality variation of 1%. The resulting accuracy of the

temperature sensor at room temperature will be:

± ± ±

3˚C + ( 1% of 298 ˚K) = 6 ˚C.

T_ACC

=

The additional inaccuracy in the temperature measurement

caused by η, can be eliminated if each temperature sensor is

calibrated with the remote diode that it will be paired with.

3.2 PCB LAYOUT for MINIMIZING NOISE

In a noisy environment, such as a processor mother board,

layout considerations are very critical. Noise induced on

traces running between the remote temperature diode sen-

sor and the LM83 can cause temperature conversion errors.

The following guidelines should be followed:

1. Place a 0.1 µF power supply bypass capacitor as close

as possible to the V_CCpin and the recommended 2.2 nF

capacitor as close as possible to the D+ and D− pins.

Make sure the traces to the 2.2nF capacitor are

matched.

2. The recommended 2.2nF diode bypass capacitor actu-

ally has a range of 200pF to 3.3nF. The average tem-

perature accuracy will not degrade. Increasing the ca-

pacitance will lower the corner frequency where

differential noise error affects the temperature reading

thus producing a reading that is more stable. Con-

versely, lowering the capacitance will increase the cor-

ner frequency where differential noise error affects the

temperature reading thus producing a reading that is

less stable.

DS101058-15

Pentium or 3904 Temperature vs LM83 Temperature

Reading

Most silicon diodes do not lend themselves well to this appli-

cation. It is recommended that a 2N3904 transistor base

emitter junction be used with the collector tied to the base.

3. Ideally, the LM83 should be placed within 10cm of the

Processor diode pins with the traces being as straight,

short and identical as possible. Trace resistance of 1Ω

can cause as much as 1˚C of error.

A diode connected 2N3904 approximates the junction avail-

able on a Pentium microprocessor for temperature measure-

ment. Therefore, the LM83 can sense the temperature of this

diode effectively.

4. Diode traces should be surrounded by a GND guard ring

to either side, above and below if possible. This GND

guard should not be between the D+ and D− lines. In the

event that noise does couple to the diode lines it would

be ideal if it is coupled common mode. That is equally to

the D+ and D− lines.(See Figure 10)

3.1 ACCURACY EFFECTS OF DIODE NON-IDEALITY

FACTOR

The technique used in today’s remote temperature sensors

is to measure the change in V_BEat two different operating

points of a diode. For a bias current ratio of N:1, this differ-

ence is given as:

5. Avoid routing diode traces in close proximity to power

supply switching or filtering inductors.

17

www.national.com

4.0 Application Hints (Continued)

6. Avoid running diode traces close to or parallel to high

speed digital and bus lines. Diode traces should be kept

at least 2cm. apart from the high speed digital traces.

7. If it is necessary to cross high speed digital traces, the

diode traces and the high speed digital traces should

cross at a 90 degree angle.

8. The ideal place to connect the LM83’s GND pin is as

close as possible to the Processors GND associated

with the sense diode. For the Pentium II this would be

pin A14.

DS101058-17

FIGURE 10. Ideal Diode Trace Layout

9. Leakage current between D+ and GND should be kept

to a minimum. One nano-ampere of leakage can cause

as much as 1˚C of error in the diode temperature read-

ing. Keeping the printed circuit board as clean as pos-

sible will minimize leakage current.

Noise coupling into the digital lines greater than 300mVp-p

(typical hysteresis), overshoot greater than 500mV above

_CC, and undershoot less than 500mV below GND, may pre-

V

vent successful SMBus communication with the LM83. SM-

Bus no acknowledge is the most common symptom, causing

unnecessary traffic on the bus. Although, the SMBus maxi-

mum frequency of communication is rather low (100kHz

max) care still needs to be taken to ensure proper termina-

tion within a system with multiple parts on the bus and long

printed circuit board traces. An R/C lowpass filter with a 3db

corner frequency of about 40MHz has been included on the

LM83’s SMBCLK input. Additional resistance can be added

in series with the SMBData and SMBCLK lines to further

help filter noise and ringing. Minimize noise coupling by

keeping digital traces out of switching power supply areas as

well as ensuring that digital lines containing high speed data

communications cross at right angles to the SMBData and

SMBCLK lines.

4.0 Typical Applications

DS101058-22

FIGURE 11. LM83 Demo Board Diode Layout

www.national.com

18

4.0 Typical Applications (Continued)

DS101058-23

Any two or three D+ inputs can be connected in parallel to increase the number of High temperature setpoints for a particular temperature reading. If all three

D+ inputs are tied as shown here, D1+, D2+ and D3+ temperature readings will be identical, unless affected by PCB D+ trace resistance differences.

FIGURE 12. Connecting all Three LM83 Diode Inputs in Parallel will Increase the Number of HIGH Setpoints for a

Single Temperature Reading to Three.

19

www.national.com

Physical Dimensions inches (millimeters) unless otherwise noted

16-Lead QSOP Package

Order Number LM83CIMQA or LM83CIMQAX

NS Package Number MQA16

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NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT

DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL

COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:

1. Life support devices or systems are devices or

systems which, (a) are intended for surgical implant

into the body, or (b) support or sustain life, and

whose failure to perform when properly used in

accordance with instructions for use provided in the

labeling, can be reasonably expected to result in a

significant injury to the user.

2. A critical component is any component of a life

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can be reasonably expected to cause the failure of

the life support device or system, or to affect its

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National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.

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型号：	LM83
厂家：	TEXAS INSTRUMENTS
描述：	具有 SMBus 和 I2C 接口且兼容 ACPI 的三路远程和本地温度传感器温度传感传感器温度传感器
文件：	总22页 (文件大小：383K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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