LTC3524 Adjustable TFT Bias Supply with WLED Driver FEATURES DESCRIPTION Generates Three Adjustable, Low Noise Rails for The LTC 3524 is an integrated BIAS and white LED power Small/Medium TFT Displays converter solution for small/medium-sized polysilicon thin Drives Up to Ten White LEDs lm transistor (TFT) liquid crystal (LCD) display panels. LED Dimming and Open-Circuit Protection The device operates from a single Lithium-Ion/polymer Controlled Power-Up/Power-Down Sequencing battery or any voltage source between 2.5V and 6V. 1.5MHz Fixed Frequency, Low Noise Operation A 1.5MHz synchronous boost converter generates a pro- V Range 2.5V to 6V, V Range 3V to 6V IN OUT grammable low noise, high ef ciency 25mA TFT supply TFT Supply Ef ciency Up to 90% of up to 6.0V. Regulated, low ripple charge pumps are LED Supply Ef ciency Up to 78% used to generate up to +20V and 20V at 2mA. Output Two Independantly Enabled LED Strings sequencing is internally controlled to insure proper TM 200 to 1 True Color PWM Dimming initialization and rapid discharge of the LCD panel in Tiny External Solution shutdown. 24-Lead QFN Package (4mm 4mm 0.75mm) A second 1.5MHz boost converter powers one or two LED strings with up to ve series elements each. LED current APPLICATIONS and display brightness can be controlled over a wide range using analog or digital means up to 25mA. PDAs, Palmtop Computers Digital Still and Video Cameras The LTC3524 is offered in the 4mm 4mm 24-pin QFN Handheld GPS package, minimizing the total solution footprint. Portable Instrument Displays , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. True Color PWM is a registered trademarks of Linear Technology Corporation. All other Portable Media Players trademarks are the property of their respective owners. TYPICAL APPLICATION LCD Bias and LED Ef ciency +5V, 7.5V, +12.5V, 8 LED Power Supply V = 3.6V, V = 5V, 8 LEDs IN OUT 100 V = 3.6V + 10H 3.3H IN 2.2F Li-Ion 10F SW1 V SW2 IN 90 VLED LCD +5V V OUT LED2 25mA 80 10F 1M LED 324k FBVO LED1 VNIN +10V PROG V2x 70 100k for 20mA ELED2 + LTC3524 0.47F C2 ELED1 0.1F ELCD V IN C2 470k +12.5V VH FBN V OUT 60 2mA 5 10 15 20 25 0.47F 1M 2M 220k V OR LED STRING CURRENT (mA) 7.5V OUT FBH VN 2mA 3524 TA01b + + CH CH GND CN 0.47F 0.1F 0.1F 3524 TA01a 3524f 1 EFFICIENCY (%)LTC3524 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Referred to GND) TOP VIEW V , SW1, V , C2 ....................................... 0.3 to 7V IN OUT ELCD, ELED1, ELED2, PROG ......................... 0.3 to 7V FBN, FBH, FBVO ............................................. 0.3 to 7V 24 23 22 21 20 19 + V2x, C2 , CH .............................................. 0.3 to 13V ELCD 1 18 LED2 LED1, LED2, VLED, SW2 ............................. 0.3 to 22V V 2 17 CH IN + + + VN , VH, CH , CN ...................................... 0.3 to 21V FBVO CH IN 3 16 25 VN .............................................................. 21 to +0.3V V 4 15 VH OUT SW1 5 14 FBH Operating Temperature Range (Note 2) ...40C to 85C C2 6 13 FBN Storage Temperature Range ...................65C to 125C 7 8 9 10 11 12 UF PACKAGE 24-LEAD (4mm 4mm) PLASTIC QFN T = 125C, = 37C/W JMAX JA EXPOSED PAD (PIN 25) MUST BE SOLDERED TO PCB AND CONNECTED TO GND ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3524EUF PBF LTC3524EUF TRPBF 3524 24-Lead (4mm 4mm) Plastic QFN 40C to 85C LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3524EUF LTC3524EUF TR 3524 24-Lead (4mm 4mm) Plastic QFN 40C to 85C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. For more information on lead free part marking, go to: