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TCA9543A

SCPS206B – MARCH 2014 – REVISED NOVEMBER 2019

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(1)

Two interrupts can be active at the same time.

8.6.4 Interrupt Handling

The TCA9543A provides two interrupt inputs (one for each channel) and one open-drain interrupt output (see

Table 2). When an interrupt is generated by any device, it is detected by the TCA9543A and the interrupt output

is driven low. The channel does not need to be active for detection of the interrupt. A bit also is set in the control

register.

Bit 4 and Bit 5 of the control register correspond to the INT0 and INT1 inputs of the TCA9543A, 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 then can address the

TCA9543A and read the contents of the control register to determine which channel contains the device

generating the interrupt. The master then can reconfigure the TCA9543A 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 VCC through a pull-up resistor.

Table 2. Control Register Read (Interrupt)(1)

D7

D6

INT1

INT0

D3

D2

B1

B0

COMMAND

X

X

X

0

X

X

X

X

No interrupt on channel 0

1

Interrupt on channel 0

X

X

0

X

X

X

X

X

No interrupt on channel 1

1

Interrupt on channel 1

0

0

0

0

0

0

0

0

No channel selected; power-up/reset default state