PCA9626B

The PCA9626 is an I2C-bus controlled 24-bit LED driver optimized for voltage switch

dimming and blinking 100 mA Red/Green/Blue/Amber (RGBA) LEDs. Each LED output

has its own 8-bit resolution (256 steps) fixed frequency individual PWM controller that

operates at 97 kHz 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 fixed 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 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 PCA9626 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.

The PCA9626 is one of the first LED controller devices in a new Fast-mode Plus (Fm+)

family. Fm+ devices offer higher frequency (up to 1 MHz) and more densely populated

bus operation (up to 4000 pF).

The active LOW Output Enable input pin (OE) blinks all the LED outputs and can be used

to externally PWM the outputs, which is useful when multiple devices must 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 PCA9626 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. Seven hardware address pins allow up to

126 devices on the same bus.

The Software Reset (SWRST) Call allows the master to perform a reset of the PCA9626

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.

In addition to these features found in PCA9633, PCA9634, PCA9635, PCA9622 and

PCA9624, a new feature to control LED output pattern is incorporated in the PCA9626. A

new control byte called ‘Chase Byte’ allows enabling or disabling of selective LED outputs

depending on the value of the Chase Byte. This feature greatly reduces the number of

bytes to be sent to the PCA9626 when repetitive patterns must be displayed as in creating

a marquee chasing effect.

If the PCA9626 on-chip 100 mA NAND FETs do not provide enough current or voltage to

drive the LEDs, then the PCA9634 and the PCA9635 with larger current or higher voltage

external drivers can be used.

2. Applications

 RGB or RGBA LED drivers

 LED status information

 LED displays

 LCD backlights

 Keypad backlights for cellular phones or handheld devices