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Maxim > Products > [LED Lighting and LCD Display ICs]  [Power and Battery Management] 
MAX1578, MAX1579
Complete Bias and White LED Power Supplies for Small TFT Displays

First Complete LCD Bias and WLED Backlight Supplies for Small TFT Displays


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Status
Active: In Production.

Data Sheet
FULL DATA SHEET (PDF, 264kB)
Download this datasheet in PDF formatDownload   Send this datasheet to any email addressE-Mail

Description
The MAX1578/MAX1579 provide four regulated outputs to meet all the voltage requirements for small activematrix 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 converter for driving up to 8 series white LEDs for backlighting. 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 needed. 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 multistage, high-voltage charge pumps generate +15V and -10V to provide VON and VOFF, respectively. Utilizing a unique clocking scheme and internal drivers, these charge pumps eliminate parasitic charge-current glitches 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 temperature 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.

An evaluation kit is available:  MAX1579EVKIT  

Key Features   Applications/Uses
  		• Four Regulators in One Package
  		• Bias Power Using Charge Pumps
    +5V at 25mA for Source Driver`
    +15V at 100µA for VON
    -10V at 100µA for VOFF
    No External Diodes Required
    Output Sequencing
    POS, NEG, and MAIN Are Autodischarged During Shutdown
  		• LED Backlight Power Using Boost Converter
    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 Component Size
    Temperature Derating Function (MAX1579)
  		• High Efficiency
    Bias: 83% (5.0V at 25mA, 15V/-10V at 100µA)
    LED: 84% (6 LEDs at 20mA)
  		• Uses Only Ceramic Capacitors and Only One Inductor
  		• Independent Enable Inputs for LED and Bias Power
  		• Thermal-Shutdown Protection
  		• 1µA Shutdown Current
  		• Tiny 4mm x 4mm Thin QFN Package

    		  
  		• Internet Appliances
  		• LCD Displays with White LED Backlight
  		• PDAs, Palmtops
  		• Smartphones

    Key Specifications:  White LED Drivers
    Part Number Topology LEDs Config. Dimming Control VCURR_SENSE
    (mV)    		 POUT
    (W)    		 ILED
    (mA)    		 VIN
    (V)    		 VIN
    (V)    		 ICC
    (mA)    		 VOUT
    (V)    		 Oper. Freq.
    (kHz)    		 Package/Pins Price
    max num. of max min max max max See Notes
    MAX1578  Inductor Based 8 Series
    Analog
    PWM
    		 300 0.9 25 2.7 5.5 5 32 1000
    TQFN/24
    		 $3.50 @1k
    MAX1579 
    TQFN/24
    		 $3.50 @1k
    See All White LED Drivers (46)

    Diagram
    MAX1578, MAX1579: Typical Application Circuit
    Typical Application Circuit

    Evaluation Kits
  		• MAX1579EVKIT

    Design Guides
  		• Displays (PDF)
  		• Power Management for Battery-Powered Equipment (PDF)

    Reliability Reports
  		• Show FIT data for:
  		• Request Reliability Report for:

    Software/Models
    none

    Ordering Information
    Notes:

    1. Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales.
    2. Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within one business day.
    3. Part number suffixes: T or T&R = tape and reel;+ = RoHS/lead-free;# = RoHS/lead-exempt. More: SeeFull Data Sheet or Part Naming Conventions.
    4. * Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses. Note that "+", "#", "-" in the part number suffix describes RoHS status. Package drawings may show a different suffix character.


    Devices: 1-8 of 8

    MAX1578 Free
    Sample    		 Buy Status
    Package: TYPE PINS FOOTPRINT
      DRAWING CODE/VAR *
    		Temp RoHS/Lead-Free?
    Materials Analysis
    MAX1578ETG  
    		Active TQFN;24 pin;17 mm²
    Outline Drawing: 21-0139 (PDF)
    Land Pattern: 90-0022 (PDF)
    Use pkgcode/variation: T2444-4*
    		-40°C to +85°C RoHS/Lead-Free: No
    Materials Analysis
    MAX1578ETG-T    
    		Active

    Land Pattern: Not Available

    		-40°C to +85°C See data sheet
    MAX1578ETG+  
    		Active TQFN;24 pin;17 mm²
    Outline Drawing: 21-0139 (PDF)
    Land Pattern: 90-0022 (PDF)
    Use pkgcode/variation: T2444+4*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX1578ETG+T    
    		Active TQFN;24 pin;17 mm²
    Outline Drawing: 21-0139 (PDF)
    Land Pattern: 90-0022 (PDF)
    Use pkgcode/variation: T2444+4*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX1579 Free
    Sample    		 Buy Status
    Package: TYPE PINS FOOTPRINT
      DRAWING CODE/VAR *
    		Temp RoHS/Lead-Free?
    Materials Analysis
    MAX1579ETG+T    
    		Active TQFN;24 pin;17 mm²
    Outline Drawing: 21-0139 (PDF)
    Land Pattern: 90-0022 (PDF)
    Use pkgcode/variation: T2444+4*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX1579ETG+  
    		Active TQFN;24 pin;17 mm²
    Outline Drawing: 21-0139 (PDF)
    Land Pattern: 90-0022 (PDF)
    Use pkgcode/variation: T2444+4*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX1579ETG  
    		Active TQFN;24 pin;17 mm²
    Outline Drawing: 21-0139 (PDF)
    Land Pattern: 90-0022 (PDF)
    Use pkgcode/variation: T2444-4*
    		-40°C to +85°C RoHS/Lead-Free: No
    Materials Analysis
    MAX1579ETG-T    
    		Active TQFN;24 pin;17 mm²
    Outline Drawing: 21-0139 (PDF)
    Land Pattern: 90-0022 (PDF)
    Use pkgcode/variation: T2444-4*
    		-40°C to +85°C RoHS/Lead-Free: No
    Materials Analysis

    More Information
  		• New Product Press Release 2004-09-09 
  		• Product Ad: Download

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    Document Ref.: 19-3359; Rev 1; 2005-09-14
    This page last modified: 2005-09-14


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