The PCAL9555APW,118 is a low-voltage 16-bit General Purpose Input/Output (GPIO) expanderwith interrupt and weak pull-up resistors for I²C-bus/SMBus applications. NXP® I/Oexpanders provide a simple solution when additional I/Os are needed while keepinginterconnections to a minimum, for example, in ACPI power switches, sensors, pushbuttons, LEDs, fan control, etc.
In addition to providing a flexible set of GPIOs, the wide VDD range of 1.65 V to 5.5 Vallows the PCAL9555APW,118 to interface with next-generation microprocessors andmicrocontrollers where supply levels are dropping down to conserve power.
The PCAL9555APW,118 contains the PCA9555 register set of four pairs of 8-bit Configuration,Input, Output, and Polarity Inversion registers, and additionally, the PCAL9555APW,118 hasAgile I/O, which are additional features specifically designed to enhance the I/O. Theseadditional 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 PCAL9555APW,118 is a pin-to-pin replacement to the PCA9555, however, the PCAL9555Apowers up with all I/O interrupts masked. This mask default allows for a board bring-upfree of spurious interrupts at power-up.
The PCAL9555APW,118 open-drain interrupt (INT) output is activated when any input state differsfrom its corresponding Input Port register state and is used to indicate to the systemmaster that an input state has changed.
INT can be connected to the interrupt input of a microcontroller. By sending an interruptsignal on this line, the remote I/O can inform the microcontroller if there is incoming dataon its ports without having to communicate via the I²C-bus. Thus, the PCAL9555APW,118 canremain a simple slave device.
The device outputs have 25 mA sink capabilities for directly driving LEDs while consuminglow device current.
The power-on reset sets the registers to their default values and initializes the device statemachine.
The device powers on with weak pull-up resistors enabled that can replace externalcomponents.
Three hardware pins (A0, A1, A2) select the fixed I²C-bus address and allow up to eightdevices to share the same I²C-bus/SMBus.
Feature
- I²C-bus to parallel port expander
- Operating power supply voltage range of 1.65 V to 5.5 V
- Low standby current consumption
- 1.5 μA (typical at 5 V VDD)
- 1.0 μA (typical at 3.3 V VDD)
- Schmitt-trigger action allows slow input transition and better switching noise immunityat the SCL and SDA inputs
- Vhys = 0.10 x VDD (typical)
- 5 V tolerant I/Os
- Open-drain active LOW interrupt output (INT)
- 400 kHz Fast-mode I²C-bus
- Internal power-on reset
- Power-up with all channels configured as inputs and weak pull-up resistors
- No glitch on power-up
- Latched outputs with 25 mA drive maximum capability for directly driving LEDs
- Latch-up performance exceeds 100 mA per JESD78, Class II
- ESD protection exceeds JESD22
- 2000 V Human Body Model (A114-A)
- 1000 V Charged-Device Model (C101)
- Packages offered: TSSOP24, HVQFN24
- Pin to pin replacement for PCA9555 and PCA9555A with interrupts disabled atpower-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 falltimes in low capacitance applications
- Input latch: Input Port register values changes are kept until the Input Port registeris 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 changesstate
