12-Bit Plus Sign Temperature Sensors with

6

_______________________________________________________________________________________

Write Byte Format

S

ADDRESS

WR

ACK

COMMAND

ACK

DATA

ACK

P

7 bits

8 bits

8 bits

Slave Address:

equivalent

to chip-select line of a 3-

wire interface

Command Byte: selects

register you are writing to

Data Byte: data goes into the register set by the

command byte

Write Word Format

S

ADDRESS

WR

ACK

COMMAND

ACK

DATA

ACK

DATA

ACK

P

7 bits

8 bits

8 bits

(MSB)

8 bits

(LSB)

Slave Address:

equivalent to chip-select

line of a

3-wire interface

Command Byte:

selects register you

are writing to

Data Bytes: data goes into the

register set by the command

byte

Read Byte Format

S

ADDRESS

WR

ACK

COMMAND

ACK

S

ADDRESS

RD

ACK

DATA

///

P

7 bits

8 bits

7 bits

8 bits

Slave Address: equivalent

to chip-select line

Command Byte:

selects register you

are reading from

Slave Address: repeated due to

change in data-flow direction

Data Byte: reads from the

register set by the command

byte

Read Word Format

S

ADDRESS

WR

ACK

COMMAND

ACK

S

ADDRESS

RD

ACK

DATA

ACK

DATA

///

P

7 bits

8 bits

7 bits

8 bits

(MSB)

8 bits

(LSB)

Slave Address:

equivalent to chip-

select line

Command Byte:

selects register you

are reading from

Slave Address: repeated

due to change in data-flow

direction

Data Bytes: reads from the

register set by the command

byte

S = Start condition

Shaded = Slave transmission

P = Stop condition

/// = Not acknowledged

Figure 1. SMBus Protocols

Figure 2. SMBus Write Timing Diagram

SMBCLK

AB

C

D

E

FG

H

I

J

K

SMBDATA

A = START CONDITION

B = MSB OF ADDRESS CLOCKED INTO SLAVE

C = LSB OF ADDRESS CLOCKED INTO SLAVE

D = R/W BIT CLOCKED INTO SLAVE

E = SLAVE PULLS SMBDATA LINE LOW

L

M

F = ACKNOWLEDGE BIT CLOCKED INTO MASTER

G = MSB OF DATA CLOCKED INTO SLAVE

H = LSB OF DATA CLOCKED INTO SLAVE

I = SLAVE PULLS SMBDATA LINE LOW

J = ACKNOWLEDGE CLOCKED INTO MASTER

K = ACKNOWLEDGE CLOCK PULSE

L = STOP CONDITION, DATA EXECUTED BY SLAVE

M = NEW START CONDITION