Rainbow Electronics MAX6692 User Manual
Page 7
MAX6648/MAX6692
Precision SMBus-Compatible Remote/Local
Temperature Sensors with Overtemperature Alarms
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7
2) If the MAX6648/MAX6692 are in run mode, read the
status byte. If the BUSY bit indicates that a conversion
is in progress, wait until the conversion is complete
(BUSY bit set to zero) before reading the temperature
data. Following a conversion completion, immediately
read the contents of the temperature data registers. If
no conversion is in progress, the data can be read
within a few microseconds, which is a sufficiently short
period of time to ensure that a new conversion cannot
be completed until after the data has been read.
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 MASTER
H = LSB OF DATA CLOCKED INTO MASTER
I = MASTER PULLS DATA LINE LOW
J = ACKNOWLEDGE CLOCKED INTO SLAVE
K = ACKNOWLEDGE CLOCK PULSE
L = STOP CONDITION
M = NEW START CONDITION
Figure 2. SMBus Write Timing Diagram
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)
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
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
Figure 1. SMBus Protocols
S
ADDRESS
RD
ACK
DATA
///
P
7 bits
8 bits
WR
S
ACK
COMMAND
ACK
P
8 bits
ADDRESS
7 bits
P
1
ACK
DATA
8 bits
ACK
COMMAND
8 bits
ACK
WR
ADDRESS
7 bits
S
S
ADDRESS
WR
ACK
COMMAND
ACK
S
ADDRESS
7 bits
8 bits
7 bits
RD
ACK
DATA
8 bits
///
P