Diodes PAM2846 - Manual

PAM2846
Document number: DSxxxxx Rev. 1 - 2
1 of 14
www.diodes.com
November 2012
© Diodes Incorporated
PAM2846
A Product Line of
Diodes Incorporated
INTEGRATED 6 STRING LED BOOST TYPE DRIVER
Description
The PAM2846 is a high-efficiency boost type LED driver. It is
designed for large LCD panel that employs an array of LEDs as back
light source.
The PAM2846 employs a current-mode step-up converter that drives
six parallel strings of LEDs connected in multiple series. This built-in
string current-control circuit achieves ±1% typical current matching
between strings, which ensures even brightness for all LEDs. The
device is able to adapt to different numbers of LEDs in each string or
different forward voltage for different types of LEDs and keep the
string current constant.
Separate feedback loops limit the output voltage if one or more LEDs
open or short. The limit voltage of over voltage protection is
adjustable by changing the feedback resistor ratio. The PAM2846 has
features cycle-by-cycle current limit to provide consistent operation
and soft-start capability. A thermal-shutdown circuit provides another
level of protection.
The PAM2846 has a wide +4.8V to +28V input voltage range and
provides adjustable full-scale LED current. The switching frequency of
this device can be selected among 500kHz, 1MHz and 1.6 MHz
according to the application requirements.
Features
 Six Constant-Current Output Channels
 Parallel Channels Allow Higher Current per LED String
 Maximum 40V Continuous Voltage Output Limit for Each
Channel
 Self-adaptive V
OUT
to Fit Different LED Number
 Adjustable Constant LED Current
 Drives 10 or more LEDs Each String as Long as the String
Voltage Less Than 40V
 Internal 2.5A Power MOSFET
 Low 400mV Feedback Voltage at Full Current Improves
Efficiency
 Allows Digital PWM and Analog Dimming
 Wide (100:1) PWM Dimming Range without Color Shift
 Independent Dimming and Shutdown Control of the LED Driver
 Open LED Protection: Adjustable Clamp Voltage
 Short LED Protection
 3 Frequencies Selection: 1.6MHz/1MHz/500kHz
 Wide Input Voltage Range: 4.8V to 28V
 Over Temperature Protection
 Available in 24-pin 4mmx4mm QFN Package
 Pb-free Package
Pin Assignments
Applications
 White or RGB Backlighting for LCD TV, LCD Monitor, Notebook,
Handy Terminals, and Avionics Displays Panels
 LED Lighting Devices