driver. PCA9956B Datasheet

PCA9956B Datasheet PDF

Part PCA9956B
Description LED driver
Feature PCA9956B 24-channel Fm+ I2C-bus 57 mA/20 V constant current LED driver Rev. 1.2 — 10 June 2020 Pr.
Manufacture NXP
Download PCA9956B Datasheet

PCA9956B 24-channel Fm+ I2C-bus 57 mA/20 V constant current PCA9956B Datasheet

24-channel Fm+ I2C-bus 57 mA/20 V constant current LED
Rev. 1.2 — 10 June 2020
Product data sheet
1. General description
The PCA9956B is an I2C-bus controlled 24-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 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 122 Hz
and an adjustable frequency between 15 Hz to once 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.
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 PCA9956B 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 A to 57 mA.
This device has built-in open, short load and overtemperature detection circuitry. The error
information from the corresponding register can be read via the I2C-bus. Additionally, a
thermal shutdown feature protects the device when internal junction temperature exceeds
the limit allowed for the process.
The PCA9956B device has a Fast-mode Plus (Fm+) I2C-bus interface. Fm+ devices offer
higher frequency (up to 1 MHz) or 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 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 PCA9956B 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. On power-up, PCA9956B will have a unique
Sub Call address to identify it as a 24-channel LED driver. This allows mixing of devices
with different channel widths. Three hardware address pins on PCA9956B allow up to
125 devices on the same bus.
The Software Reset (SWRST) function allows the master to perform a reset of the
PCA9956B through the I2C-bus, identical to the Power-On Reset (POR) that initializes the
registers to their default state causing the output current switches to be OFF (LED off).
This allows an easy and quick way to reconfigure all device registers to the same

NXP Semiconductors
24-channel Fm+ I2C-bus 57 mA/20 V constant current LED driver
2. Features and benefits
Product data sheet
24 LED drivers. Each output programmable at:
Programmable LED brightness
Programmable group dimming/blinking mixed with individual LED brightness
Programmable LED output delay to reduce EMI and surge currents
24 constant current output channels can sink up to 57 mA, tolerate up to 20 V when
Output current adjusted through an external resistor (Rext input)
Output current accuracy
4 % between output channels
6 % between PCA9956B devices
Open/short load/overtemperature detection mode to detect individual LED errors (Rext
< 3 k)
1 MHz Fast-mode Plus compatible I2C-bus interface with 30 mA high drive capability
on SDA output for driving high capacitive buses
256-step (8-bit) linear programmable brightness per LED output varying from fully off
(default) to maximum brightness using a 31.25 kHz PWM signal
256-step group brightness control allows general dimming (using a 122 Hz PWM
signal) from fully off to maximum brightness (default)
256-step group blinking with frequency programmable from 15 Hz to 16.8 s 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’).
Active LOW Output Enable (OE) input pin allows for hardware blinking and dimming of
the LEDs
Three quinary hardware address pins allow 125 PCA9956B devices to be connected
to the same I2C-bus and to be individually programmed
Four software programmable I2C-bus addresses (one LED Group Call address and
three LED Sub Call addresses) allow groups of devices to be addressed at the same
time in any combination (for example, one register used for ‘All Call’ so that all the
PCA9956Bs on the I2C-bus can be addressed at the same time and the second
register used for three different addresses so that 13 of all devices on the bus can be
addressed at the same time in a group). Software enable and disable for each
programmable I2C-bus address.
Unique power-up default Sub Call address allows mixing of devices with different
channel widths
Software Reset feature (SWRST Call) allows the device to be reset through the
8 MHz internal oscillator requires no external components
Internal power-on reset
Noise filter on SDA/SCL inputs
No glitch on LEDn outputs on power-up
Low standby current
Operating power supply voltage (VDD) range of 3 V to 5.5 V
All information provided in this document is subject to legal disclaimers.
Rev. 1.2 — 10 June 2020
© NXP Semiconductors B.V. 2020. All rights reserved.
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