The PCA9531D,112 is a 8-bit I2C-bus and SMBus I/O Expander optimized for dimming LEDs in 256 discrete steps for red/green/blue (RGB) colour mixing and back light applications. The PCA9531 contains an internal oscillator with two user programmable blink rates and duty cycles coupled to the output PWM. The LED brightness is controlled by setting the blink rate high enough (>100Hz) that the blinking cannot be seen and then using the duty cycle to vary the amount of time the LED is on and thus the average current through the LED. The initial setup sequence programs the two blink rates/duty cycles for each individual PWM. From then on, only one command from the bus master is required to turn individual LEDs on, off, blink rate 1 or blink rate 2. Based on the programmed frequency and duty cycle, blink rate 1 and blink rate 2 will cause the LEDs to appear at a different brightness or blink at periods up to 1.69 second.
8 LED drivers (ON, OFF, flashing at a programmable rate)
Input/outputs not used as LED drivers can be used as regular GPIOs
Internal oscillator requires no external components
I2C-bus Interface logic compatible with SMBus
Internal power-ON reset
Noise filter on SCL/SDA input
Active low reset input
8 Open-drain outputs directly drive LEDs to 25mA
Edge rate control on outputs
No glitch on power-up
Supports hot insertion
Low standby current consumption
Latch-up testing is done to JEDEC standard JESD78 which exceeds 100mA
(EN)
