LTC3128 3A Monolithic Buck-Boost Supercapacitor Charger and Balancer with Accurate Input Current Limit FEATURES DESCRIPTION n 2% Accurate Average Input Current Limit The LTC 3128 is a highly efficient, buck-boost DC/DC Programmable Up to 3A supercapacitor charger. It operates efficiently from input n Programmable Maximum Capacitor Voltage Limit voltages above, below or equal to the output voltage. The n Active Charge Balancing for Fast Charging of LTC3128 incorporates accurate programmable average Unmatched Capacitors input current limit, active charge balancing and program- n Charges Single or Stacked Capacitors mable maximum capacitor voltage. This combination of n V Range: 1.73V to 5.5V features makes the LTC3128 ideal for safely charging and IN n V Range: 1.8V to 5.5V protecting large capacitors in backup power systems. The OUT n <2A Quiescent Current from V When Charged input current limit and maximum capacitor voltage are each OUT n Output Disconnect in Shutdown: <1A I Shutdown programmed using a single resistor. Average input current Q n Power-Good Comparator is accurately controlled over a 0.5A to 3A programmable n Power Failure Indicator range while the individual maximum capacitor voltage can n Thermally Enhanced 20-Lead (4mm 5mm 0.75mm) be set from 1.8V to 3.0V. QFN and 24-Lead TSSOP Packages Other features of the LTC3128 include <2A quiescent current from V in Burst Mode operation, accurate OUT APPLICATIONS power-good and power failure indicators, and thermal n Supercapacitor Based Backup Power overload protection. The LTC3128 is offered in low profile, n Memory Backup thermally enhanced 20-Lead 4mm 5mm 0.75mm QFN n Servers, RAID, RF Systems and 24-Lead TSSOP packages. n Industrial, Communications, Computing L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks and PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION Wide V (3A Programmed Input Current) to 4.2V IN Stacked Output Capacitors Charging Waveform 3.3H SW1 SW2 V = 4.2V OUT V RSENP OUTP V V OUT 1.7V TO 5.5V RSENS OUTS C1a 2.0V/DIV 1.87M UP TO 3.0A LTC3128 940mF V IN C1 MID MID RUN C1b 2.0V/DIV 940mF PFI FB I IN PFO 2.0A/DIV 10F PGOOD MAXV PROG 10F GND I LOAD 2.0A/DIV 127k 470pF 3.57k 301k 3128 TA01b 3128 TA01 2 SECONDS/DIV C1: Murata DMF3Z5R5H474M3DTA0 3128f 1 For more information www.linear.com/LTC3128LTC3128 ABSOLUTE MAXIMUM RATINGS (Note 1) V , RSENP, V , MID Voltage .................. 0.3V to 6V PROG, MAXV, FB, PFI Voltage ..................... 0.3V to 6V IN OUTP RSENS, V Voltage ................................. 0.3V to 6V PGOOD, PFO DC Current ........................................15mA OUTS RSENS DC Current ....................................................4A Operating Junction Temperature Range SW1, SW2 DC Voltage ................................. 0.3V to 6V (Notes 2, 4) ............................................ 40C to 125C SW1, SW2 Pulsed (<100ns) Voltage .............1.0V to 7V Storage Temperature Range .................. 65C to 150C PGOOD, PFO, RUN Voltage .......................... 0.3V to 6V Lead Temperature (Soldering, 10 sec) FE Only .............................................................300C PIN CONFIGURATION TOP VIEW TOP VIEW SW1 1 24 SW2 GND 2 23 SW2 20 19 18 17 GND 3 22 NC SW1 4 21 V OUTP SW1 1 16 V OUTP RSENP 5 20 V RSENP 2 15 V OUTP OUTP RSENS 3 14 V RSENS 6 25 19 V OUTS OUTS 21 GND GND RUN 4 13 MID RUN 7 18 MID PROG 5 12 PGOOD PROG 8 17 PGOOD NC 6 11 FB NC 9 16 FB 7 8 9 10 NC 10 15 MAXV V 11 14 PFI IN GND 12 13 PFO UFD PACKAGE 20-LEAD (4mm 5mm) PLASTIC QFN FE PACKAGE T = 125C, = 43C/W JMAX JA 24-LEAD PLASTIC TSSOP EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB (NOTE 5) T = 125C, = 38C/W JMAX JA EXPOSED PAD (PIN 25) SHOULD BE SOLDERED TO PCB (NOTE 5) ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3128EUFD PBF LTC3128EUFD TRPBF 3128 20-Lead (4mm 5mm) Plastic QFN 40C to 125C LTC3128IUFD PBF LTC3128IUFD TRPBF 3128 40C to 125C 20-Lead (4mm 5mm) Plastic QFN LTC3128EFE PBF LTC3128EFE TRPBF LTC3128FE 24-Lead Plastic TSSOP 40C to 125C LTC3128IFE PBF LTC3128IFE TRPBF LTC3128FE 24-Lead Plastic TSSOP 40C to 125C Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: