• 简体中文
• English

PCAL9555A: Low-voltage 16-bit I²C-bus GPIO with Agile I/O, interrupt and weak pull-up

The PCAL9555A is a low-voltage 16-bit General Purpose Input/Output (GPIO) expander with interrupt and weak pull-up resistors for I²C-bus/SMBus applications. NXP I/O expanders provide a simple solution when additional I/Os are needed while keeping interconnections to a minimum, for example, in ACPI power switches, sensors, push buttons, LEDs, fan control, etc.

In addition to providing a flexible set of GPIOs, the wide VDD range of 1.65 V to 5.5 V allows the PCAL9555A to interface with next-generation microprocessors and microcontrollers where supply levels are dropping down to conserve power.

The PCAL9555A contains the PCA9555 register set of four pairs of 8-bit Configuration, Input, Output, and Polarity Inversion registers, and additionally, the PCAL9555A has Agile I/O, which are additional features specifically designed to enhance the I/O. These additional features are: programmable output drive strength, latchable inputs, programmable pull-up/pull-down resistors, maskable interrupt, interrupt status register, programmable open-drain or push-pull outputs.

The PCAL9555A is a pin-to-pin replacement to the PCA9555, however, the PCAL9555A powers up with all I/O interrupts masked. This mask default allows for a board bring-up free of spurious interrupts at power-up.

The PCAL9555A open-drain interrupt (INT) output is activated when any input state differs from its corresponding Input Port register state and is used to indicate to the system master that an input state has changed.

INT can be connected to the interrupt input of a microcontroller. By sending an interrupt signal on this line, the remote I/O can inform the microcontroller if there is incoming data on its ports without having to communicate via the I²C-bus. Thus, the PCAL9555A can remain a simple slave device.

The device outputs have 25 mA sink capabilities for directly driving LEDs while consuming low device current.

The power-on reset sets the registers to their default values and initializes the device state machine.

The device powers on with weak pull-up resistors enabled that can replace external components.

Three hardware pins (A0, A1, A2) select the fixed I²C-bus address and allow up to eight devices to share the same I²C-bus/SMBus.

Outline 3d SOT355-1

• Pin to pin replacement for PCA9555 and PCA9555A with interrupts disabled at power-up Software backward compatible with PCA9555 and PCA9555A
• Output port configuration: bank selectable push-pull or open-drain output stages
• Interrupt status: read-only register identifies the source of an interrupt
• Bit-wise I/O programming features: Output drive strength: four programmable drive strengths to reduce rise and fall times in low capacitance applications Input latch: Input Port register values changes are kept until the Input Port register is read Pull-up/pull-down enable: floating input or pull-up/down resistor enable Pull-up/pull-down selection: 100 kΩ pull-up/down resistor selection Interrupt mask: mask prevents the generation of the interrupt when input changes state

Data Sheets (1)

Application Notes (1)

Package Information (2)

Packing (2)

Supporting Information (1)

Design Support

• Expert mode sample code for 16-bit Totem Pole (REV 1.0) TXT 16-BIT-TOTEM-POLE-READ-WRITE 12/10/2014

Package Information

Product ID	Package Description	Outline Version	Reflow/Wave Soldering	Packing	Product Status	Part NumberOrdering code(12NC)	Marking	Chemical Content	RoHS / Pb Free / RHF	LeadFree Conversion Date	EFR	IFR(FIT)	MTBF(hour)	MSL	MSL LF
PCAL9555APW		SOT355-1	SSOP-TSSOP-VSO-WAVE	Reel 13" Q1/T1	Active	PCAL9555APW,118 (9352 980 71118)	PCAL9555A	PCAL9555APW		Always Pb-free	0.0	4.0	2.5E8	1	1
PCAL9555AHF		SOT994-1		Reel 13" Q2/T3	Active	PCAL9555AHF,128 (9352 980 72128)	L55A	PCAL9555AHF		Always Pb-free	0.0	4.0	2.5E8	1	1