PCA9955B
16-channel Fm+ I
2
C-bus 57 mA/20 V constant current LED
driver
Rev. 2.2 — 10 June 2020
Product data sheet
1. General description
The PCA9955B is an I
2
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 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.
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
A
to 57 mA.
Gradation control for all current sources is achieved via the I
2
C-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.
This device has built-in open, short load and overtemperature detection circuitry. The error
information from the corresponding register can be read via the I
2
C-bus. Additionally, a
thermal shutdown feature protects the device when internal junction temperature exceeds
the limit allowed for the process.
The PCA9955B device has a Fast-mode Plus (Fm+) I
2
C-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 I
2
C-bus addresses allow all or
defined groups of PCA9955B devices to respond to a common I
2
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, PCA9955B has a unique
NXP Semiconductors
PCA9955B
16-channel Fm+ I
2
C-bus 57 mA/20 V constant current LED driver
Sub Call address to identify it as a 16-channel LED driver. This unique address allows
mixing of devices with different channel widths. Three hardware address pins on
PCA9955B allow up to 125 devices on the same bus.
The Software Reset (SWRST) function allows the master to perform a reset of the
PCA9955B through the I
2
C-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
condition.
2. Features and benefits
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 (R
ext
input)
Output current accuracy
4
% between output channels
6
% between PCA9955B devices
Open/short load/overtemperature detection mode to detect individual LED errors (R
ext
< 3 kΩ)
1 MHz Fast-mode Plus compatible I
2
C-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 fully ON 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 condition 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
PCA9955B
All information provided in this document is subject to legal disclaimers.
© NXP Semiconductors B.V. 2020. All rights reserved.
Product data sheet
Rev. 2.2 — 10 June 2020
2 of 62
NXP Semiconductors
PCA9955B
16-channel Fm+ I
2
C-bus 57 mA/20 V constant current LED driver
Three quinary hardware address pins allow 125 PCA9955B devices to be connected
to the same I
2
C-bus and to be individually programmed
4 software programmable I
2
C-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
PCA9955Bs on the I
2
C-bus can be addressed at the same time and the second
register used for three different addresses so that
1
⁄
3
of all devices on the bus can be
addressed at the same time in a group). Software enable and disable for each
programmable I
2
C-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
I
2
C-bus
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 (V
DD
) range of 3 V to 5.5 V
5.5 V tolerant inputs on non-LED pins
40 C
to +105
C
operation
ESD protection exceeds 4000 V HBM per JESD22-A114
Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA
Packages offered: HTSSOP28
3. Applications
Amusement products
RGB or RGBA LED drivers
LED status information
LED displays
LCD backlights
Keypad backlights for cellular phones or handheld devices
Fade-in and fade-out for breathlight control
Automotive lighting (PCA9955BTW/Q900)
PCA9955B
All information provided in this document is subject to legal disclaimers.
© NXP Semiconductors B.V. 2020. All rights reserved.
Product data sheet
Rev. 2.2 — 10 June 2020
3 of 62
NXP Semiconductors
PCA9955B
16-channel Fm+ I
2
C-bus 57 mA/20 V constant current LED driver
4. Ordering information
Table 1.
Ordering information
Topside mark
PCA9955BTW
Package
Name
PCA9955BTW
Description
Version
SOT1172-3
HTSSOP28 plastic thermal enhanced thin shrink small outline
package; 28 leads; body width 4.4 mm;
lead pitch 0.65 mm; exposed die pad
HTSSOP28 plastic thermal enhanced thin shrink small outline
package; 28 leads; body width 4.4 mm;
lead pitch 0.65 mm; exposed die pad
Type number
PCA9955BTW/Q900
[1]
PCA9955BTW
SOT1172-3
[1]
PCA9955BTW/Q900 is AEC-Q100 compliant.
4.1 Ordering options
Table 2.
Ordering options
Orderable
part number
PCA9955BTWJ
Package
Packing method
Minimum Temperature
order
quantity
T
amb
=
40 C
to +105
C
T
amb
=
40 C
to +105
C
Type number
PCA9955BTW
HTSSOP28 Reel 13” Q1/T1
2500
*Standard mark SMD
PCA9955BTW/Q900 PCA9955BTW/Q900J HTSSOP28 Reel 13” Q1/T1
2500
*Standard mark SMD
PCA9955B
All information provided in this document is subject to legal disclaimers.
© NXP Semiconductors B.V. 2020. All rights reserved.
Product data sheet
Rev. 2.2 — 10 June 2020
4 of 62
NXP Semiconductors
PCA9955B
16-channel Fm+ I
2
C-bus 57 mA/20 V constant current LED driver
5. Block diagram
AD0 AD1 AD2
REXT
I/O
REGULATOR
LED0
LED1
LED14
LED15
PCA9955B
DAC0
SCL
SDA
INPUT FILTER
individual LED
current setting
8-bit DACs
DAC1
I
2
C-BUS
CONTROL
DAC
14
DAC
15
V
DD
V
SS
RESET
POWER-ON
RESET
OUTPUT DRIVER, DELAY CONTROL,
ERROR DETECTION AND THERMAL SHUTDOWN
INPUT
FILTER
PWM
REGISTER X
BRIGHTNESS
CONTROL
LED STATE
SELECT
REGISTER
GRADATION
CONTROL
÷ 256
8 MHz
OSCILLATOR
31.25 kHz
GRPFREQ
REGISTER
MUX/
CONTROL
GRPPWM
REGISTER
'0' – permanently OFF
'1' – permanently ON
DIM CLOCK
OE
aaa-016962
Dim repetition rate = 122 Hz
Blink repetition rate = 15 Hz to every 16.8 seconds
Fig 1.
Block diagram of PCA9955B
PCA9955B
All information provided in this document is subject to legal disclaimers.
© NXP Semiconductors B.V. 2020. All rights reserved.
Product data sheet
Rev. 2.2 — 10 June 2020
5 of 62
京公网安备 11010802033920号
EEWORLD
