PCA9955BTW/Q900J

The PCA9955B is an I2C-bus controlled 16-channel constant current LED driver optimized for dimming and blinking 57 mA Red/Green/Blue/Amber (RGBA) LEDs in amusement products. Each LED output has its own 8-bit resolution (256 steps) fixed frequency individual PWM controller that operates at 31.25 kHz with a duty cycle that is adjustable from 0 % to 100 % to allow the LED to be set to a specific brightness value. An additional 8-bit resolution (256 steps) group PWM controller has both a fixed frequency of 122 Hz and an adjustable frequency between 15 Hz to every 16.8 seconds with a duty cycle that is adjustable from 0 % to 99.6 % that is used to either dim or blink all LEDs with the same value. Reel 13” Q1/T1 Standard mark SMD Each LED output can be off, on (no PWM control), set at its individual PWM controller value or at both individual and group PWM controller values. The PCA9955B operates with a supply voltage range of 3 V to 5.5 V and the constant current sink LED outputs allow up to 20 V for the LED supply. The output peak current is adjustable with an 8-bit linear DAC from 225 µA to 57 mA. Gradation control for all current sources is achieved via the I2C-bus serial interface and allows user to ramp current automatically without MCU intervention. 8-bit DACs are available to adjust brightness levels for each LED current source. There are four selectable gradation control groups and each group has independently four registers to control ramp-up and ramp-down rate, step time, hold ON/OFF time and final hold ON output current. Two gradation operation modes are available for each group, one is single shot mode (output pattern once) and the other is continuous mode (output pattern repeat). Each channel can be set to either gradation mode or normal mode and assigned to any one of these four gradation control groups.

• 16 LED drivers. Each output programmable at:
  • Off
  • On
  • Programmable LED brightness
  • Programmable group dimming/blinking mixed with individual LED brightness
  • Programmable LED output delay to reduce EMI and surge currents
• Gradation control for all channels
  • Each channel can assign to one of four gradation control groups
  • Programmable gradation time and rate for ramp-up and/or ramp-down operations
  • Programmable step time (6-bit) from 0.5 ms (minimum) to 512 ms (maximum)
  • Programmable hold-on time after ramp-up and hold-off time after ramp-down (3-bit) from 0 s to 6 s
  • Programmable final ramp-up and hold-on current
  • Programmable brightness current output adjustment, either linear or exponential curve
• 16 constant current output channels can sink up to 57 mA, tolerate up to 20 V when OFF
• Output current adjusted through an external resistor (REXT input)
• Out