LED controllers
Voltage-switch drivers, constant-current
drivers, and Flash LED drivers
LEDs are used in a wide range of applications, from low-end status indicators to high-end video displays. System designers often
need the ability to control these LEDs, but can’t afford to tie up the system processor to do so. NXP’s LED controllers solve this
problem, performing a variety of control tasks while offloading the system processor. Having sent instructions to the LED controller,
the processor is free to engage in other tasks or go into a low-power state.
NXP’s LED controllers offer a variety of features needed in LED-driving applications. Some of these features include:
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Blinking and dimming capability
Pulse-width modulation (PWM) for LED control
Color mixing capabilities
Fast-mode Plus (Fm+) communication channel with data transfer rate of up to 1 Mbps over the I
2
C-bus.
Different output drive types (push-pull, open-drain voltage switch or constant-current driver)
Independent control of LEDs
LED status and fault reading
Short-circuit protection
Over-temperature protection
The devices are classified in three groups: voltage-switch drivers, constant-current drivers, and Flash LED drivers.
These groups are discussed below.
Voltage-Switch Drivers
Voltage-switch output driver devices control the LED
connected to the output pin by switching the connection
to ground or supply on or off. A series resistor connected
between the LED and the device limits the current that flows
through the LED into the device.
Voltage-switch devices have the advantage of dissipating the
heat outside the device, in the series resistor. Therefore the
device is insensitive to heat dissipation and is good for driving
multiple LEDs in series, with different forward-bias voltages
(V
f
), from the same supply.
Constant-Current Drivers
A current-regulated LED driver results in the LED light
remaining constant with the supply-voltage fluctuations.
NXP constant-current LED drivers are used for low-current
luminary lighting applications requiring accurate lighting
control independent of supply voltage, temperature, and LED
forward-bias voltage.
Flash LED Drivers
NXP Flash LED Drivers are high-efficiency, maximum-output,
small footprint devices with touch capability and an indicator
LED output feature. These devices are highly integrated with
hardware and I
2
C interface modes.
(a) Example Voltage-Switch Output Structure
(b) Example Constant-Current Output Structure
The LED controllers are supported by application boards and daughter cards, an established manufacturing infrastructure that
supports high volumes, and several technical documents. NXP helps system designers make lighting affordable, in everything
from indoor consumer electronics and appliances to outdoor decorative lighting.
LED Controllers Selection Guide
Individual PWM Resolution (Steps)
Group PWM Resolution (Steps)
Default POR LED Output State
Output Enable / PWM Control
Number of Device Addresses
LED Pin can be used as Input
Individual Brightness Control
Internal Oscillator Frequency
Programmable Output Delay
Individual PWM Frequency
Group Brightness Control
Operating Voltage Range
Number of LED Outputs
External Oscillator Input
Group PWM Frequency
Max LED Drive Voltage
Max LED Drive Current
Oscillator Calibration
LED Error Detection
Dimming Capability
Standby Current [1]
Thermal Shutdown
Blinking Capability
Pattern Sequencer
Type of LED Drive
Number of PWMs
Hardware Reset
Output Type
Interface
Function
Device
PCA9550
Blinker
2
2.3 V -
5.5 V
2.3 V -
5.5 V
2.3 V -
5.5 V
2.3 V -
5.5 V
2.3 V -
5.5 V
2.3 V -
5.5 V
2.3 V -
5.5 V
2.3 V -
5.5 V
2.3 V -
5.5 V
2.3 V -
5.5 V
2.3 V -
5.5 V
2.3 V -
5.5 V
2.3 V -
5.5 V
2.3 V -
5.5 V
2.3 V -
5.5 V
2.3 V -
5.5 V
2.1 V -
5.5 V
3.3 V -
5.5 V
3.0 V -
5.5 V
3.0 V -
5.5 V
1.9 mA
Voltage
switch
Voltage
switch
Voltage
switch
Voltage
switch
Voltage
switch
Voltage
switch
Voltage
switch
Voltage
switch
Voltage
switch
Voltage
switch
Voltage
switch
Voltage
switch
Voltage
switch
Voltage
switch
Voltage
switch
Voltage
switch
Constant
Current
(Source)
Constant
Current
Constant
Current
Constant
Current
25 mA
5V
Open Drain
Hi-Z Input
Y
2
256
-
Y
N
N
N
N
Y
N
N
N
I
2
C, Fm
2
Y
330 KHz
-
-
0.172 Hz -
44 Hz
0.172 Hz -
44 Hz
0.172 Hz -
44 Hz
0.172 Hz -
44 Hz
0.591 Hz -
152 Hz
0.591 Hz -
152 Hz
0.591 Hz -
152 Hz
0.591 Hz -
152 Hz
1.56 KHz
-
In Production
PCA9553
Blinker
4
1.9 mA
25 mA
5V
Open Drain
Hi-Z Input
Y
2
256
-
N
N
N
N
N
Y
N
N
N
I
2
C, Fm
1
N
330 KHz
-
-
-
In Production
PCA9551
Blinker
8
1.9 mA
25 mA
5V
Open Drain
Hi-Z Input
Y
2
256
-
N
N
N
N
N
Y
N
N
N
I
2
C, Fm
8
Y
330 KHz
-
-
-
In Production
PCA9552
Blinker
Dimmer &
Blinker
Dimmer &
Blinker
Dimmer &
Blinker
Dimmer &
Blinker
Dimmer &
Blinker
Dimmer &
Blinker
Dimmer &
Blinker
Dimmer &
Blinker
Dimmer
Dimmer &
Blinker
Dimmer &
Blinker
Dimmer &
Blinker
16
2,1 mA
25 mA
5V
Open Drain
Hi-Z Input
Y
2
256
-
N
N
N
N
N
Y
N
N
N
I
2
C, Fm
8
Y
330 KHz
-
-
-
In Production
PCA9530
2
1.9 mA
25 mA
5V
Open Drain
Hi-Z Input
Y
2
256
-
Y
N
N
N
Y
Y
N
N
N
I
2
C, Fm
2
Y
330 KHz
-
-
-
In Production
PCA9533
4
1.9 mA
25 mA
5V
Open Drain
Hi-Z Input
Y
2
256
-
N
N
N
N
Y
Y
N
N
N
I
2
C, Fm
2
N
330 KHz
-
-
-
In Production
PCA9531
8
1.9 mA
25 mA
5V
Open Drain
Hi-Z Input
Y
2
256
-
N
N
N
N
Y
Y
N
N
N
I
2
C, Fm
8
Y
330 KHz
-
-
-
In Production
PCA9532
16
2,1 mA
0,005
mA
3,8 mA
25 mA
-10 mA
25 mA
-10 mA
25 mA
-10 mA
25 mA
-10 mA
25 mA
-10 mA
25 mA
100 mA
5V
Open Drain
Push Pull
(Configurable)
Push Pull
(Configurable)
Push Pull
(Configurable)
Push Pull
(Configurable)
Push Pull
(Configurable)
Open Drain
Hi-Z Input
Y
2
256
256
(64)
256
-
64
(16)
256
N
N
N
N
Y
Y
N
N
N
I
2
C, Fm
8
Y
330 KHz
-
-
-
190 Hz
(6.25 KHz)
190 Hz
(97 KHz)
190 Hz
(97 KHz)
190 Hz
(97 KHz)
-
190 Hz
(97 KHz)
190 Hz
(97 KHz)
190 Hz
(97 KHz)
In Production
PCA9632
4
5V
Hi-Z
Push Pull
Logic H
Push Pull
Logic H
Push Pull
Logic H
Push Pull
Logic L
Hi-Z
N
4+1
Y
Y
N
N
Y
Y
N
N
N
I
2
C, Fm+
1, 4
1, 4,
126
1, 4,
126
126
N
400 KHz
N
N
In Production
PCA9633
4
5V
N
4+1
Y
Y
Y
N
Y
Y
N
N
N
I
2
C, Fm+
N
25 MHz
N
N
97 KHz
In Production
PCA9634
8
3,8 mA
5V
N
8+1
256
256
Y
Y
Y
N
Y
Y
N
N
N
I
2
C, Fm+
N
25 MHz
N
N
97 KHz
In Production
PCA9635
16
3,8 mA
5V
N
16 + 1
256
256
Y
Y
Y
N
Y
Y
N
N
N
I
2
C, Fm+
N
25 MHz
N
N
97 KHz
40 Hz -
1000 Hz
97 KHz
In Production
PCA9685
16
2,2 mA
5V
N
16
4096
-
Y
N
Y
Y
Y
Y
N
N
N
I
2
C, Fm+
126
N
25 MHz
N
Y
In Production
PCA9624
8
2,1 mA
40 V
N
8+1
256
256
Y
Y
Y
N
Y
Y
N
N
N
I
2
C, Fm+
126
N
25 MHz
N
N
In Production
PCA9622
16
1.05 mA
100 mA
40 V
Open Drain
Hi-Z
N
16 + 1
256
256
Y
Y
Y
N
Y
Y
N
N
N
I
2
C, Fm+
126
N
25 MHz
N
N
97 KHz
In Production
PCA9626
24
6.0 mA
100 mA
40 V
Open Drain
Hi-Z
N
24 + 1
256
256
Y
Y
Y
N
Y
Y
N
N
N
I
2
C, Fm+
126
N
25 MHz
N
N
97 KHz
In Production
PCA9901
Blinker
1
0,3 mA
1 to 20
mA
15 to 60
mA
50 mA
5V
Open Drain
(Source)
Open Drain
(Sink)
Open Drain
(Sink)
Open Drain
(Sink)
Hi-Z
N
0
4096
-
N
N
N
N
N
Y
Y
Y
Y
1-Wire
1
N
18 KHz
N
N
N
N
In Production
PCA9922
Signage
Dimmer &
Blinker
Dimmer &
Blinker
8
3.2 mA
5V
Hi-Z
N
0
-
-
N
N
Y
N
N
N
N
Y
Y
SPI, 25
MHz
I
2
C, Fm+
-
N
-
-
-
N
N
In Production
PCA9952
16
500 mA
34 V
Hi-Z
N
16 + 1
256
256
Y
Y
Y
Y
Y
Y
N
Y
Y
8, 4
Y
8 MHz
Y
N
31.5 KHz
122 Hz
In Development
PCA9955
[1]
16
500 mA
50 mA
34 V
Hi-Z
N
16 + 1
256
256
Y
Y
N
Y
Y
Y
N
Y
Y
I
2
C, Fm+
16, 4
Y
8 MHz
Y
N
31.5 KHz
122 Hz
In Development
Typical value, measured with V
DD
= 5.5 V, no load, V
I
= V
DD
or V
SS
, and F
SCL
= 0 KHz.
LED Flash Drivers Selection Guide
Maximum LED Drive Current
Integrated Diodes and Resistors
Number of Device Addresses
Flash LED Output Drive Type
Inductor Broken Coil Detect
Max Timed Flash Operation
Flash LEDs Driven in Series
Fixed Switching Frequency
Operating Voltage Range
Flash (2 LEDs)
Flash (1 LED)
Touch
Interface Type
Indicator
Output
SSL3250A
Asynchronous
boost conerter
Synchronous
boost converter
Assist Light
Function
Device
2.7 V - 5.5 V
Low-side drive
1 or 2
500 mA
500 mA
200 mA
20 mA
1.2 MHz
N
N
I
2
C, Fm or direct
1
820 ms
N
In
Production
In
Development
SSL3252
2.5 V - 5.5 V
High-side drive
1 or 2
500 mA
400 mA
160 mA
10 mA
2.0 MHz
Y
Y
I
2
C, Fm or direct
1
820 ms
Y
Status
Status
PCA9622 Application Example
Architectural Lighting
Mobile Phone Application Example
Car Radio Backlight
Application Support
For added application support, NXP offers the following application reports on the LED driver family devices:
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AN10579:
}
AN10733:
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AN264:
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AN10315:
Driving LED light bars using NXP Solutions
http://www.nxp.com/documents/application_note/AN10579.pdf
Flash LED App. Note
http://www.nxp.com/documents/application_note/AN10733.pdf
I
2
C Devices for LED Display Control App. Note
http://www.nxp.com/documents/application_note/AN264.pdf
LED Dimmer Board
http://www.nxp.com/documents/application_note/AN10315.pdf
For more information, visit http://ics.nxp.com/products/led.drivers/
NXP offers evaluation modules and demo boards that can be used to develop software and evaluate the performance
of the LED controllers and LED Flash drivers.
OM6275 – I
2
C 2005-1 Evaluation Board
Easy experimentation and training module. I
2
C-bus connects
to LED controllers, other I
2
C peripherals, and daughter cards.
USB Connection. GUI interface allows direct control of device
without programming.
OM6276 – PCA9633 Demo Board
Evaluate LED dimming and blinking features of the PCA9633
4-bit (RGBA) PWM LED driver. RJ-45 jack allows series
connection to multiple boards to evaluate long-distance Fm+
bus and P82B96.
OM6279 – LED Dimmer Demo Board
NXP LED controllers and GPIO in simulated mobile phone
application showing RGB LED color mixing, LED blinking and
dimming, and backlight LED control applications.
OM6281 – PCA9698 Daughter Card for I
2
C 2005-1
PCA9698 40-bit GPIO with easy access to all 40 I/O pins
and several LEDs. Demonstrates using PCA9530 2-bit LED
dimmer to dim and/or blink all 40 outputs using the /OE input
of the PCA9698.
OM6282 – PCA9633 Daughter Card for I
2
C 2005-1
Demonstrates LED blinking, dimming, and RGBA color mixing
using PCA9633 with individual 256-step PWM per channel
and global 256-step PWM. Select any of the 64 I
2
C addresses
with the on-board DIP switch.
LED Flash Driver Demo Board
Provides access to the reset, flash, touch and brightness
controls of the SSL3250A. The board also has a USB port and
GUI software that can be used to control the SSL3250A.
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