PCF8574P

The PCF8574P is one member of the PCF8574 series.The PCF8574 is a silicon CMOS circuit. PCF8574P provides general purpose remote I/O expansion for most microcontroller families via the two-line bidirectional bus (I2C).The device consists of an 8-bit quasi-bidirectional port and an I2C-bus interface. The PCF8574 has a low current consumption and includes latched outputs with high current drive capability for directly driving LEDs. PCF8574P also possesses an interrupt line (INT) which can be connected to the interrupt logic of the microcontroller.

Features of the PCF8574P are:(1)operating supply voltage 2.5 to 6 V; (2)low standby current consumption of 10 mA maximum; (3)I2C to parallel port expander; (4)open-drain interrupt output; (5)8-bit remote I/O port for the I2C-bus; (6)compatible with most microcontrollers; (7)latched outputs with high current drive capability for directly driving LEDs; (8)address by 3 hardware address pins for use of up to 8 devices (up to 16 with PCF8574A); (9)DIP16, or space-saving SO16 or SSOP20 packages.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. This means that the PCF8574 can remain a simple slave device.

The absolute maximum ratings of the PCF8574P can be summarized as:(1)supply voltage:-0.5 to 7V;(2)storage temperature range:-65 to 150;(3)input voltage:Vss-0.5 V to Vdd+0.5 V;(4)operating ambient temperature:-40 to 85;(5)power dissipation per output:100mW.A quasi-bidirectional I/O can be used as an input or output without the use of a control signal for data direction.At power-on the I/Os are HIGH. In this mode only a current source to VDD is active. An additional strong pull-up to VDD allows fast rising edges into heavily loaded outputs. These devices turn on when an output is written HIGH, and are switched off by the negative edge of SCL. The I/Os should be HIGH before being used as inputs.