Rainbow Electronics MAX1839 - Manual

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
Features
♦ Fast Response to Input Change
♦ Wide Input Voltage Range (4.6V to 28V)
♦ High Power-to-Light Efficiency
♦ Minimizes Transformer Voltage Stress
♦ Lamp-Out Protection with 2s Timeout
♦ Buck Switch Short and Other Single-Point Fault
Protection
♦ Integrated Royer MOSFET Drivers Reduce
Transformer Pin Count
♦ Buck Operation Synchronized to Royer Oscillator
♦ Synchronizable DPWM Frequency
♦ Pin-Selectable Brightness Control Interface
♦ SMBus Serial Interface (MAX1739)
♦ Analog Interface (MAX1739/MAX1839)
MAX1739/MAX1839
†
Wide Brightness Range
CCFL Backlight Controllers
________________________________________________________________ Maxim Integrated Products 1
20
19
18
17
16
15
14
13
1
2
3
4
5
6
7
8
BATT
DH
LX
BST CCV
CCI
MINDAC
REF
TOP VIEW
VL
GND
CS
DL1 MODE
CTL/SCL
CRF/SDA
SH/SUS
12
11
9
10
DL2
SYNC CTFB
CSAV
MAX1739
QSOP
Pin Configuration
19-1755; Rev 1; 3/01
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
† Patent pending
SMBus is a trademark of Intel Corp.
PART TEMP. RANGE PIN-PACKAGE
MAX1739EEP -40 °C to +85°C 20 QSOP
MAX1839EEP -40 °C to +85°C 20 QSOP
Ordering Information
Pin Configurations continued at end of data sheet.