Datasheet

1. General description
The PCA9952 and PCA9955 are I
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C-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 LEDn 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 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 PCA9952 and PCA9955
operate with a supply voltage range of 3 V to 5.5 V and the constant current sink LEDn
outputs allow up to 40 V for the LED supply. The output peak current is adjustable with an
8-bit linear DAC from 225 A to 57 mA.
These devices have built-in open, short load and overtemperature detection circuitry. The
error information from the corresponding register can be read via the I
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C-bus. Additionally,
a thermal shutdown feature protects the device when internal junction temperature
exceeds the limit allowed for the process.
The PCA9952 and PCA9955 devices have Fast-mode Plus (Fm+) I
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C-bus interface. Fm+
devices offer higher frequency (up to 1 MHz) or more densely populated bus operation
(up to 4000 pF).
The PCA9952 is identical to PCA9955 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 enable input pin (OE
), available only on PCA9952, blinks all the
LEDn 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 I
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C-bus addresses allow all or
defined groups of PCA9952/55 devices to respond to a common I
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C-bus address,
allowing for example, all red LEDs to be turned on or off at the same time or marquee
chasing effect, thus minimizing I
2
C-bus commands. On power-up, PCA9952/55 will have
a unique Sub Call address to identify it as a 16-channel LED driver. This allows mixing of
devices with different channel widths. Four hardware address pins on PCA9955 allow up
to 16 devices on the same bus. In the case of PCA9952, three hardware address pins
allow up to 8 devices on the same bus.
PCA9952; PCA9955
16-channel Fm+ I
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C-bus 57 mA constant current LED driver
Rev. 7 — 27 May 2013 Product data sheet