PCAL6408APW datasheet(2/48 Pages) NXP

2 / 48 page

PCAL6408A

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Product data sheet

Rev. 2 — 6 December 2012

2 of 48

NXP Semiconductors

PCAL6408A

Low-voltage translating, 8-bit I2C-bus/SMBus I/O expander

The system master can reset the PCAL6408A in the event of a time-out or other improper

operation by asserting a LOW in the RESET input. The power-on reset puts the registers

in their default state and initializes the I2C-bus/SMBus state machine. The RESET pin

causes the same reset/initialization to occur without de-powering the part.

The PCAL6408A 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 PCAL6408A can

remain a simple slave device. The input latch feature holds or latches the input pin state

and keeps the logic values that created the interrupt until the master can service the

interrupt. This minimizes the host’s interrupt service response for fast moving inputs.

The device Port P outputs have 25 mA sink capabilities for directly driving LEDs while

consuming low device current.

One hardware pin (ADDR) can be used to program and vary the fixed I2C-bus address

and allow up to two devices to share the same I2C-bus or SMBus.

Features and benefits

 I2C-bus to parallel port expander

 Operating power supply voltage range of 1.65 V to 5.5 V

 Allows bidirectional voltage-level translation and GPIO expansion between:

 1.8V SCL/SDA and 1.8V, 2.5V, 3.3V or 5V Port P

 2.5V SCL/SDA and 1.8V, 2.5V, 3.3V or 5V Port P

 3.3V SCL/SDA and 1.8V, 2.5V, 3.3V or 5V Port P

 5V SCL/SDA and 1.8V, 2.5V, 3.3V or 5V Port P

 Low standby current consumption of 1

A

 Schmitt-trigger action allows slow input transition and better switching noise immunity

at the SCL and SDA inputs

 Vhys = 0.18 V (typical) at 1.8 V

 Vhys = 0.25 V (typical) at 2.5 V

 Vhys = 0.33 V (typical) at 3.3 V

 Vhys = 0.5 V (typical) at 5 V

 5 V tolerant I/O ports

 Active LOW reset input (RESET)

 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

 No glitch on power-up

 Noise filter on SCL/SDA inputs

 Latched outputs with 25 mA drive maximum capability for directly driving LEDs

 Latch-up performance exceeds 100 mA per JESD 78, Class II

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