Freescale Semiconductor
Advance Information
Document Number: MC34844
Rev. 9.0, 3/2012
10 Channel LED Backlight Driver
with Integrated Power Supply
The 34844/A is a high efficiency, LED driver for use in backlighting
LCD displays from 10" to 20"+. Operating from supplies of 7.0 to 28 V,
the MC34844/A is capable of driving up to 160 LEDs in 10 parallel
strings. Current in the 10 strings is matched to within
±2%,
and can be
programmed via the I
2
C/SM Bus interface.
The 34844/A also includes a Pulse Width Monitor (PWM) generator
for LED dimming. The LEDs can be dimmed to one of 256 levels,
programmed through the I
2
C/SM Bus interface. Up to 65,000:1 (256:1
PWM, 256:1 Current DAC) dimming ratio.
The integrated boost converter generates the minimum output
voltage required to keep all LEDs illuminated with the selected current,
providing the highest efficiency possible.
The 34844 has an integrated boost self-clocks at a default
frequency of 600 kHz, but may be programmed via I
2
C to 150/300/
600/1200 kHz. The PWM frequency can be set from 100 Hz to 25 kHz,
or can be synchronized to an external input. If not synchronized to
another source, the internal PWM rate outputs on the CK pin. This
enables multiple devices to be synchronized together.
The 34844A has a default boost frequency of 320 kHz, but may be
programmed via I
2
C to 160/320/650/1300 kHz. The PWM frequency
can be set from 110 Hz to 27 kHz, or can be synchronized to an
external input. If not synchronized to another source, the internal PWM
rate outputs on the CK pin. This enables multiple devices to be
synchronized together.
The 34844/A also supports optical/temperature closed loop
operation and also features LED over-temperature protection, LED
short protection, and LED open circuit protection. The IC also includes
over-voltage protection, over-current protection, and under-voltage
lockout.
Features
34844
34844A
LED DRIVER
EP SUFFIX (PB-FREE)
98ASA10800D
32-PIN QFN-EP
ORDERING INFORMATION
Device
MC34844EP/R2
MC34844AEP/R2
Temperature
Range (T
A
)
-40 °C to 105 °C
Package
32 QFN-EP
• Input voltage of 7.0 to 28 V
• 2.5 A integrated boost FET
• Up to 50 mA on the 34844 LED current per channel
• Up to 80 mA on the 34844A LED current per channel
• 90% efficiency (DC:DC)
• I
2
C/SM Bus interface
• 10 channel current mirror with ±2% current matching
• Boost output voltage up to 60V, with Dynamic Headroom Control (DHC)
• PWM frequency programmable or synchronizable from 100 to 25,000 Hz for the 34844
• PWM frequency programmable or synchronizable from 110 to 27,000 Hz for the 34844A
• 32-Ld 5x5x1.0mm TQFN Package
Applications
•
•
•
•
Monitors and HDTV - up to 42 inch
Personal Computer Notebooks
GPS Screens
Small screen Televisions
* This document contains certain information on a new product.
Specifications and information herein are subject to change without notice.
© Freescale Semiconductor, Inc., 2009-2012. All rights reserved.
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