Datasheet

MAX6697
conversion results until they have been read. If the
most significant bits have not been read within an
SMBus timeout period (nominally 37ms), normal updat-
ing continues. Table 1 shows the main temperature
register (high byte) data format, and Table 2 shows the
extended resolution register (low byte) data format.
Diode Fault Detection
If a channel’s input DXP_ and DXN_ are left open, the
MAX6697 detects a diode fault. An open diode fault
does not cause either ALERT or OVERT to assert. A bit
in the status register for the corresponding channel is
set to 1 and the temperature data for the channel is
stored as all 1s (FFh). It takes approximately 4ms for
the MAX6697 to detect a diode fault. Once a diode fault
is detected, the MAX6697 goes to the next channel in
7-Channel Precision Temperature Monitor
8 _______________________________________________________________________________________
Write 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
S ADDRESS RD ACK DATA /// P
7 bits 8 bits
WRS ACK COMMAND ACK P
8 bits
ADDRESS
7 bits
P
1
ACKDATA
8 bits
ACKCOMMAND
8 bits
ACKWRADDRESS
7 bits
S
S ADDRESS WR ACK COMMAND ACK S ADDRESS
7 bits8 bits7 bits
RD ACK DATA
8 bits
/// P
Figure 2. SMBus Protocols
TEMP (°C) DIGITAL OUTPUT
>127 0111 1111
127 0111 1111
126 0111 1110
25 0001 1001
0.00 0000 0000
<0.00 0000 0000
Diode fault (open) 1111 1111
Diode fault (short) 1111 1111 or 1110 1110
Table 1. Main Temperature Register
(High Byte) Data Format
TEMP (°C) DIGITAL OUTPUT
0 000X XXXX
+0.125 001X XXXX
+0.250 010X XXXX
+0.375 011X XXXX
+0.500 100X XXXX
+0.625 101X XXXX
+0.725 110X XXXX
+0.875 111X XXXX
Table 2. Extended Resolution Temperature
Register (Low Byte) Data Format