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General description

The PCA9574 is a CMOS device that provides 8 bits of General Purpose parallel Input/Output (GPIO) expansion in low voltage processor and handheld battery powered mobile applications and was developed to enhance the NXP family of I2C-bus I/O expanders. The improvements include lower supply current, lower operating voltage of 1.1 V to 3.6 V, dual and separate supply rails to allow voltage level translation anywhere between 1.1 V and 3.6 V, 400 kHz clock frequency, and smaller packaging. Any of the 8 I/O ports can be configured as an input or output independent of each other and default on start-up to inputs. I/O expanders provide a simple solution when additional I/Os are needed while keeping interconnections to a minimum; for example in battery powered mobile applications and clamshell devices for interfacing to sensors, push buttons, keypad, etc. In addition to providing a flexible set of GPIOs, it simplifies interconnection of a processor running at one voltage level to I/O devices operating at a different (usually higher) voltage level. PCA9574 has built-in level shifting feature that makes these devices extremely flexible in mixed signal environments where communication between incompatible I/Os is required. The core of PCA9574 can operate at a voltage as low as 1.1 V while the I/O bank can operate in the range 1.1 V to 3.6 V. Bus hold with programmable on-chip pull-up or pull-down feature for I/Os is also provided.

Features

■ 400 kHz I2C-bus serial interface

■ Compliant with I2C-bus Standard-mode (100 kHz)

■ Separate supply rails for core logic and I/O bank provides voltage level shifting

■ 1.1 V to 3.6 V operation with level shifting feature

■ Very low standby current: < 1 ?A

■ 8 configurable I/O pins that default to inputs at power-up

■ Outputs:

? Totem pole: 1 mA source and 3 mA sink

? Independently programmable 100 k? pull-up or pull-down for each I/O pin

? Open-drain active LOW interrupt (INT) output pin allows monitoring of logic level change of pins programmed as inputs

■ Inputs:

? Programmable bus hold provides valid logic level when inputs are not actively driven

? Programmable Interrupt Mask Control for input pins that do not require an interrupt when their states change or to prevent spurious interrupts default to mask at power-up

? Polarity inversion register allows inversion of the polarity of the I/O pins when read

■ Active LOW reset (RESET) input pin resets device to power-up default state

■ GPIO All Call address allows programming of more than one device at the same time with the same parameters

■ 2 programmable slave addresses using 1 address pin

■ ?40 °C to +85 °C operation

■ ESD protection exceeds 7000 V HBM per JESD22-A114, 500 V MM per JESD22-A115, and 1000 V CDM per JESD22-C101

■ Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA

■ Packages offered: TSSOP16, HVQFN16 and HXQFN16U

Applications

■ Cell phones

■ Media players

■ Multi voltage environments

■ Battery operated mobile gadgets

■ Motherboards

■ Servers

■ RAID systems

■ Industrial control

■ Medical equipment

■ PLCs