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

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

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)

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.

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.