MAX1996A Datasheet, PDF (1/28 Pages) Maxim Integrated Products – High-Efficiency, Wide Brightness Range, CCFL Backlight Controller

19-2267; Rev 1; 10/02
High-Efficiency, Wide Brightness
Range, CCFL Backlight Controller
General Description
The MAX1996A integrated controller is optimized to
drive cold-cathode fluorescent lamps (CCFLs) using
synchronized full-bridge inverter architecture.
Synchronized drive provides near sinusoidal waveforms
over the entire input range to maximize the life of
CCFLs. The controller also operates over a wide input-
voltage range with high efficiency and broad dimming
range.
The MAX1996A includes safety features that limit the
transformer secondary voltage and protect against sin-
gle-point fault conditions including lamp-out and short-
circuit faults.
The MAX1996A regulates the CCFL brightness in three
ways: linearly controlling the lamp current, digital pulse-
width modulating (DPWM) the lamp current, or using
both methods simultaneously to achieve the widest
dimming range (>30:1). CCFL brightness can be con-
trolled with either an analog voltage or a 2-wire
SMBus™-compatible interface. The MAX1996A directly
drives the four external N-channel power MOSFETs of
the full bridge inverter. An internal 5.3V linear regulator
powers the MOSFET drivers, the synchronizable DPWM
oscillator, and most of the internal circuitry.
The MAX1996A has the same pin configuration as the
MAX1895, but with modified SMBus slave address
(0x58) and command bytes. In addition, the lamp-out
protection timer has been reduced to approximately 1s
and the DPWM frequency is guaranteed from 200Hz to
220Hz over the operating temperature range without
external components or trimming. The MAX1996A is
available in the space-saving 28-pin thin QFN package
and operates over a -40°C to +85°C temperature
range.
Applications
Notebook Computers
Multibulb LCD Monitors
Portable Display Electronics
Ordering Information
PART
MAX1996AETI
TEMP RANGE
-40°C to +85°C
MAX1996AEGI* -40°C to +85°C
*Contact factory for availability.
PIN-PACKAGE
28 Thin QFN 5 ✕ 5
28 QFN 5 ✕ 5
Features
o SMBus Slave Address (0x58) for Wide Dimming
Range Inverters
o Guaranteed 200Hz to 220Hz DPWM Frequency
o Externally Synchronizable DPWM Frequency
o Lamp-Out Protection with 1s Timeout
o Synchronized to Resonant Frequency
Good Crest Factor for Longer Lamp Life
Ensures Maximum Strike Capability
o High Power-to-Light Efficiency
o Wide Dimming Range (3 Methods)
Lamp Current Adjust: >3 to 1
DPWM: >10 to 1
Combined: >30 to 1
o Feed-Forward for Fast Response to Step Change
of Input Voltage
o Wide Input-Voltage Range (4.6V to 28V)
o Transformer Secondary Voltage Limiting to
Reduce Transformer Stress
o Protected Against Short-Circuit and Other Single-
Point Faults
o Dual-Mode Brightness Control Interface
o Small Footprint 28-Pin Thin QFN (5mm ✕ 5mm)
Package
TOP VIEW
Pin Configuration
ILIM 1
REF 2
MINDAC 3
GND 4
MODE 5
CRF/SDA 6
CTL/SCL 7
MAX1996A
21 GH2
20 LX2
19 BST2
18 BST1
17 LX1
16 GH1
15 GL1
SMBus is a trademark of Intel Corp.
THIN QFN
5mm × 5mm
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.