Rainbow Electronics MAX6690 - Manual (Page 10)

MAX6690
2°C Accurate Remote/Local Temperature
Sensor with SMBus Serial Interface
10 ______________________________________________________________________________________
Figure 4. SMBus Write Timing Diagram
Figure 5. SMBus Read Timing Diagram
ACK
7 bits
ADDRESS ACK WR
8 bits
DATA ACK
1
P
8 bits
S COMMAND
Write Byte Format
Read Byte Format
Send Byte Format Receive Byte Format
Slave Address: equiva-
lent to chip-select line of
a 3-wire interface Command Byte: selects which
register you are writing to Data Byte: data goes into the register
set by the command byte (to set
thresholds, configuration masks, and
sampling rate)
ACK
7 bits
ADDRESS ACK WR S ACK
8 bits
DATA
7 bits
ADDRESS RD
8 bits
/// P S COMMAND
Slave Address: equiva-
lent to chip-select line Command Byte: selects
which 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
ACK
7 bits
ADDRESS WR
8 bits
COMMAND ACK P S ACK
7 bits
ADDRESS RD
8 bits
DATA /// P S
Command Byte: sends com-
mand with no data, usually
used for one-shot command Data Byte: reads data from
the register commanded
by the last Read Byte or
Write Byte transmission;
also used for SMBus Alert
Response return address
S = Start condition Shaded = Slave transmission
P = Stop condition /// = Not acknowledged
SMBCLK
A = START CONDITION
B = MSB OF ADDRESS CLOCKED INTO SLAVE
C = LSB OF ADDRESS CLOCKED INTO SLAVE
D = R/W BIT CLOCKED INTO SLAVE
A B C D E F G H I J
SMBDATA
t SU:STA t HD:STA
t LOW t HIGH
t SU:DAT
K L M
t SU:STO t BUF
E = SLAVE PULLS SMBDATA LINE LOW
F = ACKNOWLEDGE BIT CLOCKED INTO MASTER
G = MSB OF DATA CLOCKED INTO MASTER
H = LSB OF DATA CLOCKED INTO MASTER I = MASTER PULLS DATA LINE LOW
J = ACKNOWLEDGE CLOCKED INTO SLAVE
K = ACKNOWLEDGE CLEAR PULSE J = STOP CONDITION, DATA
EXECUTED BY SLAVE
K = NEW START CONDITION
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
Figure 3. SMBus Protocols