Datasheet PCF8574, PCF8574A (NXP)

PCF8574; PCF8574A Remote 8-bit I/O expander for I2C-bus with interrupt Rev. 5 — 27 May 2013 Product data sheet 1. General description
The PCF8574/74A provides general-purpose remote I/O expansion via the two-wire bidirectional I2C-bus (serial clock (SCL), serial data (SDA)). The devices consist of eight quasi-bidirectional ports, 100 kHz I2C-bus interface, three hardware address inputs and interrupt output operating between 2.5 V and 6 V. The quasi-bidirectional port can be independently assigned as an input to monitor interrupt status or keypads, or as an output to activate indicator devices such as LEDs. System master can read from the input port or write to the output port through a single register. The low current consumption of 2.5 A (typical, static) is great for mobile applications and the latched output ports directly drive LEDs. The PCF8574 and PCF8574A are identical, except for the different fixed portion of the slave address. The three hardware address pins allow eight of each device to be on the same I2C-bus, so there can be up to 16 of these I/O expanders PCF8574/74A together on the same I2C-bus, supporting up to 128 I/Os (for example, 128 LEDs). The active LOW open-drain interrupt output (INT) can be connected to the interrupt logic of the microcontroller and is activated when any input state differs from its corresponding input port register state. It is used to indicate to the microcontroller that an input state has changed and the device needs to be interrogated without the microcontroller continuously polling the input register via the I2C-bus. The internal Power-On Reset (POR) initializes the I/Os as inputs with a weak internal pull-up 100 A current source.
2. Features and benefits
I2C-bus to parallel port expander 100 kHz I2C-bus interface (Standard-mode I2C-bus) Operating supply voltage 2.5 V to 6 V with non-overvoltage tolerant I/O held to VDD with 100 A current source 8-bit remote I/O pins that default to inputs at power-up Latched outputs directly drive LEDs Total package sink capability of 80 mA Active LOW open-drain interrupt output Eight programmable slave addresses using three address pins Low standby current (2.5 A typical) 40 C to +85 C operation ESD protection exceeds 2000 V HBM per JESD22-A114 and 1000 V CDM per JESD22-C101 Document Outline 1. General description 2. Features and benefits 3. Applications 4. Ordering information 4.1 Ordering options 5. Block diagram 6. Pinning information 6.1 Pinning 6.2 Pin description 7. Functional description 7.1 Device address 7.1.1 Address maps 8. I/O programming 8.1 Quasi-bidirectional I/Os 8.2 Writing to the port (Output mode) 8.3 Reading from a port (Input mode) 8.4 Power-on reset 8.5 Interrupt output (INT) 9. Characteristics of the I2C-bus 9.1 Bit transfer 9.1.1 START and STOP conditions 9.2 System configuration 9.3 Acknowledge 10. Application design-in information 10.1 Bidirectional I/O expander applications 10.2 How to read and write to I/O expander (example) 10.3 High current-drive load applications 10.4 Migration path 11. Limiting values 12. Thermal characteristics 13. Static characteristics 14. Dynamic characteristics 15. Package outline 16. Handling information 17. Soldering of SMD packages 17.1 Introduction to soldering 17.2 Wave and reflow soldering 17.3 Wave soldering 17.4 Reflow soldering 18. Soldering of through-hole mount packages 18.1 Introduction to soldering through-hole mount packages 18.2 Soldering by dipping or by solder wave 18.3 Manual soldering 18.4 Package related soldering information 19. Soldering: PCB footprints 20. Abbreviations 21. Revision history 22. Legal information 22.1 Data sheet status 22.2 Definitions 22.3 Disclaimers 22.4 Trademarks 23. Contact information 24. Contents