The PCA9671 provides general purpose remote I/O expansion for most microcontroller
families via the two-line bidirectional bus (I2C-bus) and is a part of the Fast-mode Plus
(Fm+) family.
The PCA9671 is a drop in upgrade for the PCF8575 providing higher I2C-bus speeds
(1 MHz versus 400 kHz) so that the output can support PWM dimming of LEDs, higher
I2C-bus drive (30 mA versus 3 mA) so that many more devices can be on the bus without
the need for bus buffers, higher total package sink capacity (400 mA versus 100 mA) that
supports having all 25 mA LEDs on at the same time and more device addresses (64
versus 8) to allow many more devices on the bus without address conflicts.
