LTC3205 Multidisplay LED Controller FEATURES DESCRIPTIO n Step-Up/Step-Down Fractional Charge Pump for Up The LTC 3205 is a highly integrated multidisplay LED con- to 92% Efficiency troller. The part contains a high efficiency, low noise frac- n Independent Current and Dimming Control for tional step-up/step-down charge pump to provide power 1-4 LED Main, 1-2 LED Sub and RGB LED Displays for both main and sub white LED displays plus an RGB n LED Currents Programmable Using 3-Wire Serial color LED display. The LTC3205 requires only four small Interface ceramic capacitors plus two resistors to form a complete n Up to 250mA of Continuous LED Current 3-display LED power supply and current controller. n 0.7% LED Current Matching Maximum currents for the main/sub and RGB displays are n Low Noise Constant Frequency Operation* set independently with a single resistor. Current for each n Minimal Component Count LED is controlled with an internal current source. Dim- n Automatic Soft-Start Limits Inrush Current ming and ON/OFF control for all displays are achieved via n Four Programmable Dimming States for Main and a 3-wire serial interface. Four dimming states exist for the Sub Displays main and sub displays and 16 dimming states are available n Up to 4096 Color Combinations for RGB Display via internal PWM for the red, green and blue LEDs result- n Low Shutdown Current: I < 1A CC ing in up to 4096 color combinations. n Tiny 24-Lead (4mm 4mm) QFN Package The LTC3205 charge pump optimizes efficiency based on U V and LED forward voltage conditions. The part powers IN APPLICATIO S up in step-down mode and automatically switches to step- up mode once any enabled LED current source begins to n Cellular Phones enter dropout. Internal circuitry prevents inrush current and n Wireless PDAs excess input noise during start-up and mode switching. n Multidisplay Handheld Devices , LTC and LT are registered trademarks of Linear Technology Corporation. The LTC3205 is available in a low profile 24-lead * U.S. Patent 6,411,531 (4mm 4mm 0.8mm) QFN package. TYPICAL APPLICATIO 4-LED Main Panel Efficiency vs Input Voltage 1F1F 100 90 V IN MAIN DISPLAY SUB DISPLAY RGB ILLUMINATOR 80 2.8V TO V CPO IN 4.5V 1F 1F 70 LTC3205 60 50 RED GREEN BLUE 4 MAIN1-4 40 2 SUB1-2 30 3 3 SERIAL 3205 TA01a SERIAL PORT RGB 20 INTERFACE FOUR LEDs AT 15mA/LED I I RGB MS (TYP V AT 15mA = 3.2V) F 10 T = 25C A 0 3.0 3.3 3.6 3.9 4.2 INPUT VOLTAGE (V) 3205 TA01b 3205f 1 EFFICIENCY (P /P ) (%) LED IN U ULTC3205 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) TOP VIEW ORDER PART V , DV , CPO to GND............................. 0.3V TO 6V IN CC NUMBER D , SCLK, LD, STEPUP, IN 24 23 22 21 20 19 ENRGB...................................... 0.3V to (DV + 0.3V) LTC3205EUF CC MAIN2 1 18 RED I (Note 4)...................................................... 250mA CPO MAIN1 2 17 SGND I I (Note 4) ..................................... 50mA MAIN1-4, SUB1,2 C2 V 3 16 IN 25 I (Note 4) ..................................... 100mA C1 4 15 CPO RED,GREEN,BLUE + C1 5 14 I MS I , I (Note 4) .................................................. 1mA MS RGB + C2 6 13 I RGB CPO Short-Circuit Duration ............................ Indefinite UF PART 7 8 9 10 11 12 Operating Temperature Range (Note 2) .. 40C to 85C MARKING Storage Temperature Range ................. 65C to 125C 3205 UF PACKAGE 24-LEAD (4mm 4mm) PLASTIC QFN T = 150C, = 37C/W, = 2C/W JMAX JA JC EXPOSED PAD IS PGND (PIN 25) MUST BE SOLDERED TO PCB Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25C. V = 3.6V, DV = 1.8V unless otherwise noted. A IN CC SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Input Power Supply V Operating Voltage l 2.8 4.5 V IN DV Operating Voltage l 1.5 5.5 V CC I Operating Current I , I , I = 0A, Step-Down Mode 70 A VIN CPO MS IRGB I = 0A, Step-Up Mode 4.2 mA CPO I Operating Current Serial Port Idle 1 A DVCC V Shutdown Current 1 A IN DV Shutdown Current 1 A CC White LED Current (MAIN1-MAIN4, SUB1, SUB2) I Servo Voltage 25A < I < 75A 1.193 1.223 1.253 V MS MS l 1.175 1.223 1.271 V Full-Scale LED Current Ratio (I /I ) MAIN1-MAIN4, SUB1, SUB2 Voltage = 1V l 368 400 432 mA/mA LED MS Half-Scale LED Current Ratio (I /I ) MAIN1-MAIN4, SUB1, SUB2 Voltage = 1V l 184 200 216 mA/mA LED MS Quarter-Scale LED Current Ratio (I /I ) MAIN1-MAIN4, SUB1, SUB2 Voltage = 1V l 92 100 108 mA/mA LED MS LED Current Matching Any Two MAIN or SUB Outputs 0.7 % RGB LED Current (RED, GREEN, BLUE) I Servo Voltage 25A < I < 75A 1.193 1.223 1.253 V RGB RGB l 1.175 1.223 1.271 V LED Current Ratio (I /I ) RED, GREEN, BLUE Voltage = 1V 360 400 440 mA/mA LED RGB RGB PWM Frequency RGB LED Switching Frequency 3.5 kHz RGB PWM (Duty Factor) Range 0/15 15/15 % 3205f 2 D MAIN3 IN SCLK MAIN4 LD SUB1 ENRGB SUB2 STEPUP BLUE DV GREEN CC U WWW