NXP Semiconductors PCA9955 16-channel Constant Current LED Driver

NXP Semiconductor PCA9955 LED Drivers are I²C controlled 16-channel constant current drivers designed for dimming and blinking 57mA Red/Green/Blue/Amber (RGBA) LEDs in amusement products. Each channel has an 8-bit resolution (256 steps) 31.25kHz PWM controller with a duty cycle that is adjustable between 0% to 99.6%. This feature allows each LED to be set to a specific brightness. An additional 8-bit resolution (256 steps) group PWM controller has both a fixed frequency and an adjustable frequency. This additional controller is used to either dim or blink all the LEDs with the same value.

The NXP PCA9955 has a Fast-mode Plus (Fm+) I²C-bus interface. Fm+ devices offer higher frequency (up to 1MHz) or more densely populated bus operation (up to 4000pF).

The PCA9955 is identical to PCA9952 except for the following differences:

• The PCA9952 has only three hardware address pins compared to four on PCA9955.
• The PCA9952 has an output enable pin (OE) and the PCA9955 does not.

The active LOW output enables input pin (OE), which is available only on PCA9952, blinks all the LEDn outputs. It can be used to externally PWM the outputs, which is useful when multiple devices need to be dimmed or blinked together without using software control.

Features

16 LED drivers. Each output programmable at:
- Off
- On
- Programmable LED brightness
- Programmable group dimming/blinking mixed with individual LED brightness
- Programmable LEDn output enable delay to reduce EMI and surge currents
16 constant current output channels can sink up to 57mA, tolerate up to 40V when OFF
Output current accuracy
- 6% between output channels
- 8% between PCA9952/55 devices
Open/short load/overtemperature detection mode to detect individual LED errors

1MHz Fast-mode Plus compatible I²C-bus interface with 30mA high drive capability on SDA output for driving high capacitive buses
256-step (8-bit) linear programmable brightness per LEDn output varying from fully off (default) to maximum brightness using a 31.25kHz PWM signal
256-step group brightness control allows general dimming (using a 122Hz PWM signal) from fully off to maximum brightness (default)
256-step group blinking with frequency programmable from 15Hz to 16.8s and duty cycle from 0% to 99.6%
Output state change programmable on the Acknowledge or the STOP Command to update outputs byte-by-byte or all at the same time (default to 'Change on STOP')