Rainbow-electronics MAX8728 User Manual download pdf

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

GON

GATEINL

OUT1

GOFF

LX1

ON/OFF

OUT1

FBI

FSEL

GND1

GND

FBP

SRC

REF

GON

DRN

MODE

THR

COMP

SHDN

LCD ENABLE

FROM T

CON

CTL

DEL

FB2

LX2

GND2

FBN

DRVN

SUPP

DRVP

BST

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

CODE

MAX8728ETJ+

-40°C to +85°C

32 TQFN-EP*

5mm x 5mm

T3255-4

Pin Configuration

MAX8728

TQFN

TOP VIEW

OUT1

CTL

LX1

BST

GND1

FB2

DRN

GON

FBN

SRC

FSEL

4567

2324 22 20 19 18

MODE

DEL

FBP

REF

GND

SHDN

DRVN

THR

COMP

FB1

GATE

GNDP

LX2

DRVP

INL

SUPP

GND2

+Denotes lead-free package.

*EP = Exposed pad.

True Shutdown is a trademark of Maxim Integrated Products, Inc.

1 2 3 4 5 6 ... 28 29

Summary of Contents

Page 1 - Low-Cost, Multiple-Output

General DescriptionThe MAX8728 generates all the supply rails for thin-filmtransistor (TFT) liquid-crystal display (LCD) panels in TVsand monitors. It

Page 2

Typical Operating Characteristics (continued)(Circuit of Figure 1. VIN= VINL= VSUPP= 12V, AVDD= 13.5V, VGON= 28V, VGOFF= -6V, VOUT1= 3.3V, FSEL = GND,

Page 3

Typical Operating Characteristics (continued)(Circuit of Figure 1. VIN= VINL= VSUPP= 12V, AVDD= 13.5V, VGON= 28V, VGOFF= -6V, VOUT1= 3.3V, FSEL = GND,

Page 4

MAX8728Low-Cost, Multiple-OutputPower Supply for LCD Monitors/TVs12 __________________________________________________________________________________

Page 5