The PCU9656 is a UFm I²C-bus controlled 24-bit LED driver optimized for voltage switch
dimming and blinking 100 mA Red/Green/Blue/Amber (RGBA) LEDs. Each LEDn output
has its own 8-bit resolution (256 steps) fixed frequency individual PWM controller that
operates at 97 kHz (typical) with a duty cycle that is adjustable from 0 % to 99.6 % 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 frequency of 190 Hz and an adjustable frequency
between 24 Hz to once every 10.73 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.
Each LEDn 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 PCU9656 operates with
a supply voltage range of 2.3 V to 5.5 V and the 100 mA open-drain outputs allow
voltages up to 40 V for the LED supply.
The PCU9656 is one of the first LED controller devices in a new Ultra Fast-mode (UFm)
family. UFm devices offer higher frequency (up to 5 MHz).
The active LOW Output Enable input pin (OE) blinks all the LEDs outputs and 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.
Software programmable LED Group and three Sub Call I²C-bus addresses allow all or
defined groups of PCU9656 devices to respond to a common I²C-bus address, allowing,
for example, all red LEDs to be turned on or off at the same time or marquee chasing
effect, thus minimizing I²C-bus commands. Six hardware address pins allow up to
64 devices on the same bus.
The Software Reset (SWRST) Call allows the controller to perform a reset of the PCU9656
through the I²C-bus, identical to the Power-On Reset (POR) that initializes the registers to
their default state causing the output NAND FETs to be OFF (LED off). This allows an
easy and quick way to reconfigure all device registers to the same condition.
A new feature to control LEDn output pattern is incorporated in the PCU9656. A new
control byte called ‘Chase Byte’ allows enabling or disabling of selective LEDn outputs
depending on the value of the Chase Byte. This feature greatly reduces the number of
bytes to be sent to the PCU9656 when repetitive patterns need to be displayed as in
creating a marquee chasing effect.