Rainbow Electronics MAX8728 - Manual

General Description
The MAX8728 generates all the supply rails for thin-film
transistor (TFT) liquid-crystal display (LCD) panels in TVs
and monitors. It includes step-down and step-up regula-
tors, positive and negative charge pumps, and a dual-
mode, logic-controlled high-voltage switch control block.
The MAX8728 can operate from input voltages from 7V to
13.2V and is optimized for LCD TV panel and LCD moni-
tor applications running directly from 12V supplies.
The step-up and step-down regulators feature internal
power MOSFETs and high-frequency operation allow-
ing the use of small inductors and capacitors, resulting
in a compact solution. Both switching regulators use
fixed-frequency, current-mode control architectures,
providing fast load-transient response and easy com-
pensation. The positive and negative charge-pump reg-
ulators provide TFT gate-driver supply voltages. Both
output voltages can be adjusted with external resistive
voltage-dividers.
The MAX8728 is available in a small (5mm x 5mm), low-
profile (0.8mm), 32-pin TQFN package and operates
over the -40°C to +85°C temperature range.
Applications
LCD Monitors LCD TVs
Features
♦ Optimized for 10.8V to 13.2V Input Supply
♦ 7V to 13.2V Input Supply Range
♦ Selectable Frequency (500kHz/1MHz/1.5MHz)
♦ Current-Mode Step-Down Regulator
14V Internal n-Channel MOSFET
1.5% Accurate Output
♦ Current-Mode Step-Up Regulator
19V Internal n-Channel MOSFET
1% Accurate Output
True Shutdown™ (Output Goes to Zero)
♦ 180° Out-of-Phase Switching
♦ Adjustable Positive/Negative Charge Pumps
♦ Soft-Start and Timer Delay Fault Latch for All
Outputs
♦ Logic-Controlled, High-Voltage Switches
♦ Power-Up and Power-Down Sequences
♦ Thermal-Overload Protection
MAX8728
Low-Cost, Multiple-Output
Power Supply for LCD Monitors/TVs
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
MAX8728
AV DD
V GON
GATE INL
V IN
OUT1
V GOFF
V L
V L
LX1 ON/OFF
OUT1
FBI
FSEL
GND1
GND
FBP
SRC REF
V CC
GON
DRN
MODE
THR
COMP
SHDN
LCD ENABLE EN
FROM T CON CTL
DEL
FB2
LX2
GND2
FBN
DRVN
SUPP DRVP
VL
BST
IN
V IN
Simplified Operating Circuit
19-3910; Rev 0; 1/06
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.
PART TEMP RANGE
PIN-
PACKAGE PACKAGE
CODE
MAX8728ETJ+ -40°C to +85°C
32 TQFN-EP*
5mm x 5mm
T3255-4
Pin Configuration
MAX8728
TQFN
TOP VIEW
29
30
28
27
12
11
13
OUT1
CTL
IN
LX1 BST
14
GND1
FB2 DRN GON FBN SRC FSEL
1 2
EN
4 5 6 7
23 24 22 20 19 18
MODE
DEL
FBP
REF
GND
SHDN
DRVN
THR
3
21
31 10 COMP V CC
32 9 FB1 VL
GATE
26 15 GNDP LX2
25 16 DRVP
INL
SUPP
8
17
GND2
+Denotes lead-free package.
*EP = Exposed pad.
True Shutdown is a trademark of Maxim Integrated Products, Inc.