The PCA962x devices have 7 hardware address pins that allow up to 124 PCA962x devices to be connected to the same I2C-bus and to be individually programmed.  Additionally, there are four software programmable I2C-bus addresses:  one LED Group Call address and three LED Sub Call addresses. These programmable addresses allow groups of devices to be addressed at the same time in any combination. For example, one register can be used for an ‘All Call’ function so that all the PCA962x devices on the I2C-bus can be addressed at the same time. The second register can be used for three different addresses so that one-third of all devices on the bus can be addressed at the same time, in a group. The picture in this slide shows different configurations in which the PCA9622 may be used to drive LEDs.