The PCA9515A is a CMOS integrated circuit intended for application in I2C-bus and SMBus systems. While retaining all the operating modes and features of the I2C-bus system, it permits  extension of the I2C-bus by buffering both the data (SDA) and the clock (SCL) lines, thus enabling two buses of 400 pF.

The I2C-bus capacitance limit of 400 pF restricts the number of devices and bus length. Using the PCA9515A enables the system designer to isolate two halves of a bus, thus more devices or longer length can be accommodated. It can also be used to run two buses, one at 5 V and the other at 3.3 V or a 400 kHz and 100 kHz bus, where the 100 kHz bus is isolated when 400 kHz operation of the other is required