Description 

This 16-bit I/O expander for the two-line bidirectional bus (I2C) is designed for 2.3-V to 5.5-V VCC operation. It provides general-purpose remote I/O expansion for most microcontroller families via the I 2C interface [serial clock (SCL), serial data (SDA)]. The PCA9555 consists of two 8-bit Configuration (input or output selection), Input Port, Output Port, and Polarity Inversion (active high or active low operation) registers. At power on, the I/Os are configured as inputs. The system master can enable the I/Os as either inputs or outputs by writing to the I/O configuration bits. The data for each input or output is kept in the corresponding Input or Output register. The polarity of the Input Port register can be inverted with the Polarity Inversion register. All registers can be read by the system master.

Features 

• Low Standby-Current Consumption of 1 μA Max • I 2C to Parallel Port Expander • Open-Drain Active-Low Interrupt Output • 5-V Tolerant I/O Ports • Compatible With Most Microcontrollers • 400-kHz Fast I 2C Bus • Address by Three Hardware Address Pins for Use of up to Eight Devices • Polarity Inversion Register • Latched Outputs With High-Current Drive Capability for Directly Driving LEDs • Latch-Up Performance Exceeds 100 mA Per JESD 78, Class II • ESD Protection Exceeds JESD 22 – 2000-V Human-Body Model (A114-A) – 200-V Machine Model (A115-A) – 1000-V Charged-Device Model (C101) 

Applications 

• Servers • Routers (Telecom Switching Equipment) • Personal Computers • Personal Electronics • Industrial Automation Equipment • Products with GPIO-Limited Processors