The PCA9959 is a daisy-chain SPI-compatible 4-wire serial bus controlled by a 24-channel constant preset current LED driver optimized for dimming and blinking 63 mA Red/green/blue/amber (RGBA) LEDs.
Each LED output has its own 6-bit resolution (64 steps) preset current configuration, with an absolute accuracy of ±8 %.
PCA9959 supports up to four groups of LED gradation control, with each LED channel assigned to one of the groups. For each group, PCA9959 supports 64-grid brightness control, with the time duration of each grid adjustable from 2.5 μs to 1 ms. Each LED output can be off, on or set at its individual preset current value within each grid. Once gradation control enabled, PCA9959 will automatically change each LED preset current with the setup from grid0 to grid63. Once finished, it can hold grid63 or repeat from grid0 as configured.