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This is an open-collector I2C board. It is a board for remote 8-output expander for I2C bus based on PCF8574A. Making it ideal as open
collector expander for I2C bus. It is designed to compatible with almost 2.5V to 5.5V microcontrollers.
The PCF8574A is the I2C bus controller which talk to microcontroller and then take commands to output
driver. The PCF8574A supports 100kHz bus frequency. And it can be connected to 2.5V-5.5V external logic voltage
of I2C port of microcontrollers.
The board uses ULN2803A for output driver which has 8 open collectors. Each outputs support 500mA for current and up to
50V for voltage.
The board is addressed by 3 jumpers to make 8 different addresses. So that 8 boards can be connected together on one
bus. Moreover 16 boards can be connected together on one bus when they have 16 different addresses. By this way, 8 boards of the
PCF8574A and 8 boards of the PCF8574 can be connected together on one bus. Because the PCF8574A doesn't have same address as
The board has inverse polarity protection circuit for power supply input voltage to prevent damage from a mistake of
connection. Also the board has LED to show status of the power supply input voltage.
The board has a small PCB size 28x51mm.
- PCF8574A I2C bus I/O expander
- 8 Outputs
- 2.5V-5.5V power supply input voltage
- Inverse polarity protection circuits
- 100kHz I2C Bus frequency
- Address by 3 jumpers for use of up to 8 addresses
- Up to 16 boards on one bus
- Compatible with almost microcontrollers
- Up to 50V load voltage
- 500mA Rated Collector Current
- Small board, PCB size 28x51mm