PCA9543A 데이터 시트보기 (PDF) - Philips Electronics
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PCA9543A Datasheet PDF : 24 Pages
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Philips Semiconductors
PCA9543A
2-channel I2C switch with interrupt logic and reset
Table 4: Control register: Write—channel selection; Read—channel status
D7 D6 INT1 INT0 D3 D2 B1 B0 Command
0
channel 0 disabled
X
X
X
X
X
X
X
1
channel 0 enabled
0
channel 1 disabled
X
X
X
X
X
X
X
1
channel 1 enabled
0
0
0
0
0
0
0
0
no channel selected;
power-up/reset default state
Remark: Channel 0 and channel 1 can be enabled at the same time. Care should be
taken not to exceed the maximum bus capacitance.
7.2.2 Interrupt handling
The PCA9543A provides 2 interrupt inputs, one for each channel, and one open-drain
interrupt output. When an interrupt is generated by any device, it will be detected by the
PCA9543A and the interrupt output will be driven LOW. The channel need not be active
for detection of the interrupt. A bit is also set in the control register.
Bit 4 and bit 5 of the control register corresponds to the INT0 and INT1 inputs of the
PCA9543A, respectively. Therefore, if an interrupt is generated by any device connected
to channel 1, the state of the interrupt inputs is loaded into the control register when a
read is accomplished. Likewise, an interrupt on any device connected to channel 0 would
cause bit 4 of the control register to be set on the read. The master can then address the
PCA9543A and read the contents of the control register to determine which channel
contains the device generating the interrupt. The master can then reconfigure the
PCA9543A to select this channel, and locate the device generating the interrupt and
clear it.
It should be noted that more than one device can provide an interrupt on a channel, so it is
up to the master to ensure that all devices on a channel are interrogated for an interrupt.
The interrupt inputs may be used as general purpose inputs if the interrupt function is not
required.
If unused, interrupt input(s) must be connected to VDD through a pull-up resistor.
Table 5: Control register: Read—interrupt
7
6
INT1 INT0 3
2
B1 B0 Command
0
no interrupt on channel 0
X
X
X
X
X
X
X
1
interrupt on channel 0
0
no interrupt on channel 1
X
X
X
X
X
X
X
1
interrupt on channel 1
Remark: Two interrupts can be active at the same time.
7.3 RESET input
The RESET input is an active LOW signal which may be used to recover from a bus fault
condition. By asserting this signal LOW for a minimum of tWL, the PCA9543A will reset its
registers and I2C-bus state machine and will deselect all channels. The RESET input must
be connected to VDD through a pull-up resistor.
9397 750 14316
Product data sheet
Rev. 03 — 21 March 2005
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
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