2.9.3 Temperature Data Readout (Addr: 001 001; 09h)

Reg

Add

Register

Name

R/

W

P

O

R

Val

Bit

15

MSb

Bit

14

Bit

13

Bit

12

Bit

11

Bit

10

Bit

9

Bit

8

Bit

7

Bit

6

Bit

5

Bit

4

Bit

3

Bit

2

Bit

1

Bit

0

LSb

001 001

Local

Temperature

Data

Readout

R

MSb

Sign

128

˚C

64˚C 32˚C 16˚C 8˚C

4˚C

2˚C

1˚C

0.5

˚C

Reserved

SNUM

Reserved

00

00

Processor/

Remote

Temperature

Data

Readout

Reserved

EF

Res

00

0

Bit

Type

Description

0RO

Reserved. Will always read "0".

1RO

Reserved for Local Temperature Data Readout. Will always read "0".

EF (Error Flag) for Remote Temperature Data Readout. This bit indicates that an error was detected

during the measurement of the current remote Temperature sensor such as a diode fault condition. When a

diode fault occurs the value of the temperature reading will be 200h or -256˚C.

0: No error detected.

1: Error detected.

3-2

RO

SNUM (Sensor Number). This field indicates the number of the current Temperature Sensor, to which the

data in the Temperature Readout field belongs. Temperature Sensor 0 is always assigned to the local

sensor of the LM40.

0: Local temperature sensor (see Table Thermal Diode Input Mapping)

1-2: Remote sensor 1 and 2 (see Table Thermal Diode Input Mapping)

5-4

RO

Reserved. Will always read "0".

15-6

RO

Temperature Readout. This field holds the result of the temperature measurement. The active size of this

field for the LM40 is 10-bits, left justified. See Table Temperature Data Format for examples.

Thermal Diode Input Mapping

Sensor Number

(SNUM)

Sensor Input

Board Connection

0

Local

none

1

Processor, D1+/D1-

CPU Thermal Diode

2

Remote, D2+/D2-

MMBT3904 Thermal Diode or GPU

Thermal Diode

All LM40 temperature data has a common format. The LM40’s temperature data format is two’s complement and has 10-bits of

resolution with the LSb having a weight of 0.5 ˚C. The LM40 can resolve temperature between +255.5 ˚C and -256 ˚C, inclusive.

It can measure local temperatures between +85 ˚C and 0 ˚C and remote temperatures between +125 ˚C and 0 ˚C with an

Temperature Data Format

Temperature

Binary

Hex

+140 ˚C

01 0001 1000

118h

+100 ˚C

00 1100 1000

0C8h

+1 ˚C

00 0000 0010

002h

0 ˚C

00 0000 0000

000h

- 0.5 ˚C

11 1111 1111

3FFh

-1 ˚C

11 1111 1110

3FEh

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