The LC709004A is a peripheral IC dedicated for expanding the capability of the microcontroller (MCU) I/O ports. It interfaces with the microcontroller through synchronous serial communication. Communication with the extended I/O ports is accomplished through 16-bit parallel I/O. The extended port features include the capabilities to specify the I/O direction on a bit basis, to specify the output type (CMOS or N-channel open drain), and to specify the I/O voltage level on a port basis according to the power level of the peripheral equipment. These features make allow the LC709004A to be used in a wide variety of applications.

• 4-/5-wire synchronous serial transmission and reception, and 16-bit parallel I/O
• Wide operating voltage range (2.0V to 6.0V)
• Multifunction I/O ports :
• I/O direction specification: Bit units
• CMOS or Nch-OD output type specification: Bit units
• Output voltage adjustment: Port (8 bits) units
• Output current: 12mA max. (capable of driving a green LED directly)
• Data transmission and reception :
• Can control reception of input data and transmission of output data in parallel.
• Cascaded configuration :
• Ports can be expanded in units of 16 bits x n (n is the number of LSI chips).