General description
The PCA9533 is a 4-bit I2C-bus and SMBus I/O expander optimized for dimming LEDs in 256 discrete steps for Red/Green/Blue (RGB) color mixing and back light applications.
The PCA9533 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 (> 100 Hz) 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.

Features
■ 4 LED drivers (on, off, flashing at a programmable rate)
■ Two selectable, fully programmable blink rates (frequency and duty cycle) between 0.591 Hz and 152 Hz (1.69 second and 6.58 milliseconds)
■ 256 brightness steps
■ 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 inputs
■ 4 open-drain outputs directly drive LEDs to 25 mA
■ Edge rate control on outputs
■ No glitch on power-up
■ Supports hot insertion
■ Low standby current
■ Operating power supply voltage range of 2.3 V to 5.5 V
■ 0 Hz to 400 kHz clock frequency
■ ESD protection exceeds 2000 V HBM per JESD22-A114, 150 V MM per JESD22-A115 and 1000 V CDM per JESD22-C101
■ Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA
■ Packages offered: SO8, TSSOP8 (MSOP8)