Rainbow Electronics MAX6635 - Manual (Page 6)

MAX6633/MAX6634/MAX6635
12-Bit Plus Sign Temperature Sensors with
SMBus/I
2 C-Compatible Serial Interface
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
A B C D E F G H I J K
SMBDATA
t SU:STA t HD:STA
t LOW t HIGH
t SU:DAT t HD:DAT t SU:STO t BUF
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