MAX8751 Datasheet, PDF (1/27 Pages) Maxim Integrated Products – Fixed-Frequency, Full-Bridge CCFL Inverter Controller

19-3784; Rev 0; 8/05
EVAALVUAAILTAIOBNLEKIT
Fixed-Frequency, Full-Bridge CCFL
Inverter Controller
General Description
The MAX8751 cold-cathode-fluorescent lamp (CCFL)
inverter controller is designed to drive multiple CCFLs
using the fixed-frequency, full-bridge inverter topology.
The MAX8751 operates in resonant mode during striking
and switches over to constant-frequency operation after
all the lamps are lit. This unique feature ensures reliable
striking under all conditions and reduces the transformer
stress.
The MAX8751 can drive large power MOSFETs typically
used in applications where one power stage drives four
or more CCFL lamps in parallel. An internal 5.35V linear
regulator powers the MOSFET drivers and most of the
internal circuitry. The controller operates over a wide
input-voltage range (6V to 28V) with high power to light
efficiency. The device also includes safety features that
effectively protect against many single-point fault condi-
tions, including lamp-out and short-circuit conditions.
The MAX8751 achieves a 10:1 dimming range by “chop-
ping” the lamp current on and off using the digital pulse-
width modulation (DPWM) method. The DPWM frequency
can be accurately adjusted with a resistor or synchro-
nized to an external signal. The brightness is controlled
by an analog voltage on the CNTL pin.
The MAX8751 is capable of synchronizing and adjusting
the phase of the gate drivers and DPWM oscillator. These
features allow multiple MAX8751 ICs to be connected in a
daisy-chain configuration. The switching frequency and
DPWM frequency can be easily adjusted using external
resistors, or synchronized with system signals. If the con-
troller loses the external sync signals, it switches over to
the internal oscillators and keeps operating. Phase-shift
select pins PS1 and PS2 can be used to program up to
four different phase shifts, allowing up to five MAX8751s
to be used together.
The MAX8751 is available in a low-profile, 32-pin TQFN
package and operates over the -40°C to +85°C tempera-
ture range.
Applications
LCD TVs
LCD Monitors
Notebook Computers
Automotive Infotainment
PART
MAX8751ETJ
Ordering Information
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
32 TQFN
Pin Configuration appears at end of data sheet.
Features
♦ All n-Type MOSFET Low-Cost, Full-Bridge,
Fixed-Frequency Inverter Topology for Highest
Efficiency
♦ Resonant-Mode Striking Ensures Startup
♦ Strong Gate Drivers Can Easily Drive Large
External MOSFETs for Multilamp Applications
♦ Adjustable DPWM Frequency with Sync and
Phase-Shift Capability
♦ 10:1 Dimming Range with Accurate Analog
Interface
♦ Lamp-Out Detection with Adjustable Timeout
♦ Secondary Current Limit with Adjustable Timeout
♦ Adjustable Secondary Voltage Limiting
♦ Adjustable DPWM Rise and Fall Time
♦ Wide Input Voltage Range (6V to 28V)
♦ 32-Pin TQFN Package
VIN
7V TO 24V
3A
GND
VCC
ON/OFF
BRIGHTNESS
Minimal Operating Circuit
IN
GND
VCC ^MAX8751
SEL
SHDN
CNTL
PCOMP
HF
LF
HFCK
HSYNC
LSYNC
LFCK
DPWM
PSCK
PS1
PS2
GH1
BST1
LX1
LX2
BST2
GL1
PGND1
PGND2
GL2
GH2
ISEC
VFB
IFB
COMP
TFLT
T1
CCFL
________________________________________________________________ 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.