MAX1578ETG+ Maxim Integrated Products, MAX1578ETG+ Datasheet

MAX1578ETG+

Manufacturer Part Number

MAX1578ETG+

Description

IC PS BIAS/WHITE LED TFT 24-TQFN

Manufacturer

Maxim Integrated Products

Datasheet

1.MAX1578ETGT.pdf (13 pages)

Specifications of MAX1578ETG+

Applications

LCD Display

Current - Supply

3mA

Voltage - Supply

2.7 V ~ 5.5 V

Operating Temperature

-40°C ~ 85°C

Mounting Type

Surface Mount

Package / Case

24-TQFN Exposed Pad

Number Of Segments

Operating Supply Voltage

2.7 V to 5.5 V

Maximum Power Dissipation

1667 mW

Maximum Operating Temperature

+ 85 C

Mounting Style

SMD/SMT

Minimum Operating Temperature

- 40 C

Lead Free Status / RoHS Status

Lead free / RoHS Compliant

Current page: 1 of 13
Download datasheet (260Kb)

The MAX1578/MAX1579 provide four regulated outputs

to meet all the voltage requirements for small active-

matrix TFT-LCD displays in handheld devices where

minimum external components and high efficiency are

required. Each device consists of three advanced

charge pumps for LCD bias power and a step-up con-

verter for driving up to 8 series white LEDs for back-

lighting. The input voltage range is from 2.7V to 5.5V.

The charge pumps provide fixed +5V, +15V, and -10V

for the LCD bias circuits. No external diodes are need-

ed. A high-efficiency, fractional (1.5x/2x) charge pump

followed by a low-dropout linear regulator provides +5V

to power the source driver. Automatic mode changing

achieves the highest conversion efficiency. Two multi-

stage, high-voltage charge pumps generate +15V and

-10V to provide V

unique clocking scheme and internal drivers, these

charge pumps eliminate parasitic charge-current glitch-

es and reduce maximum input current, resulting in low

electromagnetic emissions. The outputs are sequenced

during startup and shutdown. In shutdown, the outputs

are discharged to zero.

The high-efficiency inductor step-up converter drives

up to 8 white LEDs in series with a constant current to

provide backlighting. The series connection allows the

LED currents to be identical for uniform brightness and

minimizes the number of traces to the LEDs. The

MAX1578 regulates constant LED current over the

entire temperature range. The MAX1579 features a tem-

perature derating function to avoid overdriving the

white LEDs during high ambient temperatures, enabling

higher drive current below +42°C.

The MAX1578/MAX1579 are available in space-saving

24-lead 4mm x 4mm thin QFN packages.

19-3359; Rev 1; 8/05

+ Denotes lead-free package.

Ordering Information continued at end of data sheet.

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.

MAX1578ETG

MAX1578ETG+

PDAs, Palmtops

Smart Phones

Internet Appliances

PART

Complete Bias and White LED Power Supplies

-40°C to +85°C

TEMP RANGE

________________________________________________________________ Maxim Integrated Products

and V

Ordering Information

General Description

OFF

, respectively. Utilizing a

LCD Displays with

White LED Backlight

PIN-PACKAGE

24 Thin QFN 4mm x 4mm

(T2444-4)

24 Thin QFN 4mm x 4mm

(T2444-4)

Applications

♦ Four Regulators in One Package

♦ Bias Power Using Charge Pumps

♦ LED Backlight Power Using Boost Converter

♦ High Efficiency

♦ Uses Only Ceramic Capacitors and Only One

♦ Independent Enable Inputs for LED and Bias

♦ Thermal-Shutdown Protection

♦ 1µA Shutdown Current

♦ Tiny 4mm x 4mm Thin QFN Package

See Figure 3 for Typical Application Circuit.

for Small TFT Displays

Inductor

Power

+5V at 25mA for Source Driver

+15V at 100µA for V

-10V at 100µA for V

No External Diodes Required

Output Sequencing

POS, NEG, and MAIN Are Autodischarged

Series LED Connection for Uniform Illumination

Supports Up to 8 LEDs at 25mA (max)

900mW (max) Power

PWM or Analog Dimming Control

Overvoltage Protection

Low Input/Output Ripple

Soft-Start with Zero Inrush Current

Fast 1MHz PWM Operation for Small

Temperature Derating Function (MAX1579)

Bias: 83% (5.0V at 25mA, 15V/-10V at 100µA)

LED: 84% (6 LEDs at 20mA)

During Shutdown

Component Size

C1N

C2N

C2P

C1P

4mm x 4mm

THIN QFN

MAX1579

MAX1578

OFF

Pin Configuration

Features

GND

ONBIAS

NEG

CD2

CD1

PMPB

Related parts for MAX1578ETG+

MAX1578ETG+ Summary of contents

Page 1

... PIN-PACKAGE 24 Thin QFN 4mm x 4mm MAX1578ETG -40°C to +85°C (T2444-4) 24 Thin QFN 4mm x 4mm MAX1578ETG+ -40°C to +85°C (T2444-4) + Denotes lead-free package. Ordering Information continued at end of data sheet. ________________________________________________________________ Maxim Integrated Products For pricing delivery, and ordering information please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’ ...

Page 2

Complete Bias and White LED Power Supplies for Small TFT Displays ABSOLUTE MAXIMUM RATINGS IN, CS, C1N, C2N, MAIN, ONBIAS CTRL to GND..................-0.3V to the lesser of + LX, OUT to GND .....................................................-0.3V to +37V COMP ...

Page 3

... OSCILLATOR Operating Frequency f BOOST PWM mode Minimum Duty Cycle Pulse skipping Maximum Duty Cycle CTRL = IN GND Dual Mode is a trademark of Maxim Integrated Products, Inc. _______________________________________________________________________________________ for Small TFT Displays = -40°C to +85°C, typical values are CONDITIONS = 0 to -100µ +25°C = +85°C ...

Page 4

Complete Bias and White LED Power Supplies for Small TFT Displays ELECTRICAL CHARACTERISTICS (continued) (Circuit of Figure 3V, CTRL = ONBIAS = IN PARAMETER N-CHANNEL SWITCH LX On-Resistance I = 190mA LX LX Leakage Current ...

Page 5

Complete Bias and White LED Power Supplies (Circuit of Figure 3.6V 20mA, 4 LEDs, CTRL = IN LED LED CURRENT vs. DIRECT-PWM DUTY CYCLE PWM 0 0 ...

Page 6

Complete Bias and White LED Power Supplies for Small TFT Displays (Circuit of Figure 3.6V 20mA, 4 LEDs, CTRL = IN LED MAIN OUTPUT LOAD REGULATION 0 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 ...

Page 7

Complete Bias and White LED Power Supplies PIN NAME Logic Input to Enable V 11 ONBIAS charge pumps. Connect to GND to disable the charge pumps. 12 GND Ground. Connect to PGND and the exposed pad directly under the IC. ...

Page 8

Complete Bias and White LED Power Supplies for Small TFT Displays IN BIAS GND COMP CTRL 170mV ONBIAS OSC PMP PMPB CD2 -2X INVERTING CHARGE PUMP CD1 NEG N 8 _______________________________________________________________________________________ 1MHz OSCILLATOR PWM CONTROL REF OSC TIMER SHUTDOWN CHARGE-PUMP ...

Page 9

Complete Bias and White LED Power Supplies Detailed Description Bias Power and UVLO The MAX1578/MAX1579 contain an LED driver boost converter and three charge pumps for LCD bias. The undervoltage-lockout (UVLO) feature disables the LED boost converter and the charge ...

Page 10

Complete Bias and White LED Power Supplies for Small TFT Displays The LED boost converter utilizes a soft-start function to eliminate inrush current during startup. Once the boost converter is enabled, LX begins switching at the mini- mum duty cycle ...

Page 11

Complete Bias and White LED Power Supplies Component Selection Use only ceramic capacitors with an X5R, X7R, or bet- ter dielectric. See Table 1 for a list of recommended components. Use low-ESR ceramic capacitors. Recommended val- ues for the capacitors ...

Page 12

Complete Bias and White LED Power Supplies for Small TFT Displays Table 1. Recommended Components for the Typical Application Circuit DESIGNATION DESCRIPTION 4.7µF, 6.3V X5R ceramic capacitors (0603) C1, C8 Murata GRM188R60J475KE19 0.1µF, 6.3V X5R ceramic capacitor (0402) C2 TDK ...

Page 13

... Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 13 © 2005 Maxim Integrated Products ...

Related keywords

max157
max1578
max1556
max1551
MAX1578ETG+ datasheet
MAX1578ETG+ data sheet
MAX1578ETG+ pdf datasheet
MAX1578ETG+ component
MAX1578ETG+ part
MAX1578ETG+ distributor
MAX1578ETG+ RoHS
MAX1578ETG+ datasheet download