LTC3425 5A, 8MHz, 4-Phase Synchronous Step-Up DC/DC Converter FEATURES DESCRIPTIO n High Efficiency: Up to 95% The LTC 3425 is a synchronous, 4-phase boost converter n Up to 3A Continuous Output Current with output disconnect capable of operation below 1V n 4-Phase Operation for Low Output Ripple input. It includes four N-channel MOSFET switches and and Tiny Solution Size four P-channel synchronous rectifiers for an effective n Output Disconnect and Inrush Current Limiting R of 0.045W and 0.05W , respectively. 4-phase DS(ON) n Very Low Quiescent Current: 12m A operation greatly reduces peak inductor currents, and n 0.5V to 4.5V Input Range capacitor ripple current, and increases effective switching n 2.4V to 5.25V Adjustable Output Voltage frequency, minimizing inductor and capacitor sizes. True n Adjustable Current Limit output disconnect eliminates inrush current and allows n Adjustable, Fixed Frequency Operation from zero load current in shutdown. External Schottky diodes 100kHz to 2MHz per Phase are not required in most applications (V < 4.3V). Power OUT n Synchronizable Oscillator with Sync Output saving Burst Mode operation can be user controlled or left n Internal Synchronous Rectifiers in automatic mode. n Manual or Automatic Burst Mode Operation Other features include 1m A shutdown current, program- n Power Good Comparator mable frequency with sync in and out, programmable n <1m A Shutdown Current soft-start, antiringing control, thermal shutdown, adjust- n Antiringing Control able current limit, reference output and power good n 5mm 5mm Thermally Enhanced QFN Package comparator. U APPLICATIO S The LTC3425 is available in a small, thermally enhanced 32-pin QFN package. n Handheld Computers , LTC and LT are registered trademarks of Linear Technology Corporation. n Point-of-Load Regulators Burst Mode is a registered trademark of Linear Technology Corporation. n 3.3V to 5V Conversion TYPICAL APPLICATIO V IN 2V TO 3V 2.2F 2.7H 2.7H 2.7H 2.7H 100 V SWA SWB SWC SWD IN 90 V OUTS OFF ON SHDN V 80 OUTA Burst Mode FIXED V OUTB REFOUT OPERATION FREQUENCY 70 V OUTC V OUT MODE CCM V 60 3.3V OUTD 2A 4.7F REFEN 50 1M 10k LTC3425 4 SYNCIN 40 22pF FB BURST 30 COMP V = 2.4V IN 0.01F R 20 T SS 590k 330pF V = 3.3V OUT SYNCOUT f = 1MHz/PHASE 10 I LIM 15k 33k L = 2.7H PGOOD 0 SGND GNDA GNDB GNDC GNDD 0.01F 0.1 1 10 100 1000 10000 75k 20k LOAD CURRENT (mA) 3425 TA01 3425 TA02 C : TAIYO YUDEN JMK107BJ225MA L1-L4: TDK RLF5018T-2R7M1R8 IN C : TAIYO YUDEN JMK212BJ475MG ( 4) OUT 3425f 1 EFFICIENCY (%) U ULTC3425 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) TOP VIEW V Voltage ................................................. 0.3V to 6V IN SWA-D Voltages ..........................................0.3V to 6V V , V Voltages............................ 0.3V to 6V OUTA-D OUTS 32 31 30 29 28 27 26 25 BURST, SHDN, SS, REFEN, SYNCOUT, PGOOD, GNDA 1 24 GNDD REFOUT, CCM, SYNCIN Voltages ............... 0.3V to 6V GNDA 2 23 GNDD Operating Ambient Temperature Range SWA SWD 3 22 V 4 21 V (Note 5) .............................................. 40 C to 85 C OUTA OUTD 33 V 5 20 V OUTB OUTC Storage Temperature Range ................. 65 C to 125 C SWB 6 19 SWC Lead Temperature (Soldering, 10 sec).................. 300 C GNDB 7 18 GNDC GNDB 8 17 GNDC 9 10 11 12 13 14 15 16 UH PACKAGE 32-LEAD (5mm 5mm) PLASTIC QFN T = 125 C, q = 40 C/W 1 LAYER BOARD, JMAX JA q = 35 C/W 4 LAYER BOARD, q = 1.1 C/W JA JC EXPOSED PAD IS GND (PIN 33) MUST BE SOLDERED TO PCB ORDER PART UH PART NUMBER MARKING 3425 LTC3425EUH 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 = 25 C. V = 1.2V, V = 3.3V, R = 15k, unless otherwise noted. A IN OUT T PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Start-Up Voltage V = 0V, I < 1mA 0.88 1 V OUT LOAD Minimum Operating Voltage (Note 3) l 0.5 V Output Voltage Adjust Range l 2.4 5.25 V Feedback Regulation Voltage l 1.196 1.220 1.244 V Feedback Input Current 150 nA V Quiescent CurrentBurst Mode Operation BURST = 0V, REFEN = 0V, FB = 1.3V (Note 2) 12 25 m A OUT BURST = 0V, REFEN = 2V, FB = 1.3V (Note 2) 18 35 m A V Quiescent CurrentShutdown SHDN = 0V, V = 0V, Not Including Switch Leakage 0.1 1 m A IN OUT V Quiescent CurrentActive V = 0V, Nonswitching (Note 2) 1.8 3 mA OUT C NMOS Switch Leakage V = 5V 0.1 5 m A SW PMOS Switch Leakage V = 5V, V = 0V 0.1 10 m A SW OUT NMOS Switch On Resistance (Note 4) 0.04 W PMOS Switch On Resistance (Note 4) 0.05 W NMOS Current Limit I Resistor = 75k (Note 4) l 5.0 7.0 A LIM I Resistor = 200k (Note 4) l 1.8 2.7 A LIM 3425f 2 REFEN SS V SHDN OUTS SGND SYNCIN FB V IN COMP R T BURST I LIM REFOUT CCM PGOOD SYNCOUT U WWW