Remote 16-Bit I2C And SMBus I/O Expander With Interrupt Output

The PCF8575 provides general-purpose remote I/O expansion for most Microcontroller families via the I2C Interface serial Clock (SCL) and serial data (SDA). The device features a 16-bit quasi-bidirectional input/output (I/O) port (P07-P00, P17-P10), including latched outputs with high-current drive capability for directly driving LEDs Each quasi-bidirectional I/O CAN be used as an input or output without the use of a data-direction control signal. At power on, the I/Os are high. In this mode, only a current source (IOH) to VCC is active. An additional strong pullup to VCC (IOHT) allows fast-rising edges into heavily loaded outputs. This device turns on when an output is written high and is switched off by the negative edge of SCL. The I/Os should be high before being used as inputs. After power on, as all the I/Os are set high, all of them CAN be used as inputs. Any change in setting of the I/Os as either input or outputs CAN be done with the write mode. If a high is applied externally to an I/O that has been written earlier to low, a large current (IOL) will flow to GND. By Texas Instruments