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MAX7367/MAX7368/MAX7369
4-Channel I2C Switches/Multiplexer
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13
Channel Selection
Each channel selected contains an SD_ and SC_ pair.
Select a channel by writing a control byte after a success-
ful acknowledge of the slave address. The last 4 bits of the
control byte determine which channel(s) is selected for the
MAX7367/MAX7368 as shown in Table 1. The last 3 bits of
the control byte determine which channel is selected for
the MAX7369 as shown in Table 2. The selected channels
are activated after the stop condition. When a channel is
selected, the respective SD_/SC_ pair is logic-high, ensur-
ing no false conditions occur on the bus.
Interrupt Logic (MAX7367/MAX7369)
The MAX7367/MAX7369 have four interrupt inputs, one for
each channel, and one
INT output. The INT output is an
open-drain output that requires a pullup resistor. The
INT
output is asserted by a low-logic signal on any of the
INT_
inputs, and it is deasserted only when all the
INT_ inputs
are logic-high. Bits 4–7 of the MAX7367/MAX7369
control/interrupt register store the state of the
INT_ for
each channel as shown in Table 3 and Figures 6 and 8.
The logic level of
INT_ is not latched. Drive the respective
INT_ input high to remove the interrupt condition for the
channel. An interrupt can occur on any channel, regard-
less of whether it is selected or not selected.
After a device generates an interrupt on one of the
channels, the interrupt input is loaded into the
control/interrupt register when a read is performed. To
determine which device is generating the interrupt,
read the contents of the control/interrupt register to
determine which channel is issuing the interrupt, then
write the appropriate command to the control/interrupt
register to select the interrupted channel. Read from all
devices on the interrupted channel to determine the
exact source of the interrupt.
Table 1. MAX7367/MAX7368 Control Bits
for Channel Selection
CONTROL BIT
COMMAND
B0
0 = Channel 0 disabled (default)
1 = Channel 0 enabled
B1
0 = Channel 1 disabled (default)
1 = Channel 1 enabled
B2
0 = Channel 2 disabled (default)
1 = Channel 2 enabled
B3
0 = Channel 3 disabled (default)
1 = Channel 3 enabled
Table 2. MAX7369 Control Bits for
Channel Selection
B2
B1
B0
COMMAND
0
No channel selected (default)
0
X
No channel selected
1
0
Channel 0 selected
1
0
1
Channel 1 selected
1
0
Channel 2 selected
1
Channel 3 selected
Table 3. MAX7367/MAX7369 Interrupt
Indicator Bits
INTERRUPT BIT
STATE
INT0
0 = No channel 0 interrupt (default)
1 = Channel 0 interrupt
INT1
0 = No channel 1 interrupt (default)
1 = Channel 1 interrupt
INT2
0 = No channel 2 interrupt (default)
1 = Channel 2 interrupt
INT3
0 = No channel 3 interrupt (default)
1 = Channel 3 interrupt
7
X
X = DON'T CARE.
X
B3
B2
B1
B0
65
4
32
1
0
CHANNEL 0
CHANNEL SELECTION BITS
(READ/WRITE)
CHANNEL 1
CHANNEL 2
CHANNEL 3
Figure 7. MAX7368 Control Register
7
INT3
INT2
INT1
INT0
X
B2
B1
B0
65
4
32
1
0
CHANNEL SELECTION BITS
(READ/WRITE)
INTERRUPT BITS
(READ ONLY)
ENABLE BIT
X = DON'T CARE.
Figure 8. MAX7369 Control/Interrupt Register