MAX1739 Datasheet, PDF (1/26 Pages) Maxim Integrated Products – Wide Brightness Range CCFL Backlight Controllers

19-1755; Rev 1; 3/01
Wide Brightness Range
CCFL Backlight Controllers
General Description
The MAX1739/MAX1839 fully integrated controllers are
optimized to drive cold-cathode fluorescent lamps
(CCFLs) using the industry-proven Royer oscillator
inverter architecture. The Royer architecture provides
near sinusoidal drive waveforms over the entire input
range to maximize the life of CCFLs. The MAX1739/
MAX1839 optimize this architecture to work over a wide
input voltage range, achieve high efficiency, and maxi-
mize the dimming range.
The MAX1739/MAX1839 monitor and limit the trans-
former center-tap voltage when required. This ensures
minimal voltage stress on the transformer, which
increases the operating life of the transformer and
eases its design requirements. These controllers also
provide protection against many other fault conditions,
including lamp-out and buck short faults.
These controllers achieve 50:1 dimming range by
simultaneously adjusting lamp current and “chopping”
the CCFL on and off using a digitally adjusted pulse-
width modulated (DPWM) method. CCFL brightness is
controlled by an analog voltage or is set with an
SMBus^TM-compatible two-wire interface (MAX1739).
The MAX1739/MAX1839 drive an external high-side
N-channel power MOSFET and two low-side N-channel
power MOSFETs, all synchronized to the Royer oscilla-
tor. An internal 5.3V linear regulator powers the MOS-
FET drivers and most of the internal circuitry. The
MAX1739/MAX1839 are available in space-saving
20-pin QSOP packages and operate over the -40°C to
+85°C temperature range.
________________________Applications
Notebook/Laptop Computers
Car Navigation Displays
LCD Monitors
Point-of-Sale Terminals
Portable Display Electronics
†_{Patent pending}
SMBus is a trademark of Intel Corp.
Features
o Fast Response to Input Change
o Wide Input Voltage Range (4.6V to 28V)
o High Power-to-Light Efficiency
o Minimizes Transformer Voltage Stress
o Lamp-Out Protection with 2s Timeout
o Buck Switch Short and Other Single-Point Fault
Protection
o Integrated Royer MOSFET Drivers Reduce
Transformer Pin Count
o Buck Operation Synchronized to Royer Oscillator
o Synchronizable DPWM Frequency
o Pin-Selectable Brightness Control Interface
o SMBus Serial Interface (MAX1739)
o Analog Interface (MAX1739/MAX1839)
PART
MAX1739EEP
MAX1839EEP
Ordering Information
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
20 QSOP
20 QSOP
Pin Configuration
TOP VIEW
REF 1
MINDAC 2
CCI 3
CCV 4
SH/SUS 5
CRF/SDA 6
CTL/SCL 7
MODE 8
CSAV 9
CTFB 10
MAX1739
20 BATT
19 DH
18 LX
17 BST
16 VL
15 GND
14 CS
13 DL1
12 DL2
11 SYNC
QSOP
Pin Configurations continued at end of data sheet.
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