PCAL9554B_PCAL9554C

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© NXP B.V. 2012. All rights reserved.

Product data sheet

Rev. 2 — 10 December 2012

15 of 42

NXP Semiconductors

PCAL9554B; PCAL9554C

8.

Application design-in information

resistor as shown in Figure 12. Since the LED acts as a diode, when the LED is off the

Designs needing to minimize current consumption, such as battery power applications,

Figure 13 shows a high value resistor in parallel with the LED, which is not needed with

the PCAL9554B or PCAL9554C that integrate a weak pull-up resistor on all pins.

consumption when the LED is off.

Device address is 0100 000x for this example using PCAL9554B (address for PCAL9554C is 0111 000x).

P0, P2, P3 configured as outputs.

P1, P4, P5 configured as inputs.

P6, P7 are not used and need 100 k

 pull-up resistors to protect them from floating or the internal pull-up or pull-down

selected.

(1) No resistors are required for inputs (on P port) that may float due to the weak pull-up integrated into the device.

Fig 12. Typical application

PCAL9554B

P0

P1

SCL

SDA

(3.3 V)

MASTER

CONTROLLER

SCL

SDA

INT

P2

INT

10 kΩ

SUB-SYSTEM 1

(e.g., temp sensor)

P3

INT

SUB-SYSTEM 2

(e.g., counter)

RESET

controlled

switch

(e.g., CBT device)

A

B

enable

002aah211

10 kΩ

10 kΩ

2 kΩ

100 kΩ

(× 3)(1)

P4

P5

A1

A0

SUB-SYSTEM 3

(e.g., alarm system)

ALARM

P6

P7

A2