POWER LOSS (mW) LTC3873-5 TM No R Constant SENSE Frequency Current Mode Boost/Flyback/SEPIC DC/DC Controller FEATURES DESCRIPTION n V and V Limited Only by External Components The LTC 3873-5 is a constant frequency current mode IN OUT n Internal or Programmable External Soft-Start controller for boost, yback or SEPIC DC/DC converters n Constant Frequency 200kHz Operation designed to drive an N-channel MOSFET for high input n Adjustable Current Limit and output voltage converter applications. n Current Sense Resistor Optional The LTC3873-5 provides 1.5% output voltage accuracy n 1.5% Voltage Reference Accuracy and consumes only 300A quiescent current during nor- n Current Mode Operation for Excellent Line and Load mal operation and only 50A during micropower start-up. Transient Response Using a 9.3V internal shunt regulator, the LTC3873-5 can n 4.1V Undervoltage Threshold for Logic Level be powered from a high input voltage through a resistor MOSFET Applications or it can be powered directly from a low impedance DC n Low Quiescent Current: 300A voltage of 9V or less. Soft-start can be programmed using TM n Low Pro le (1mm) ThinSOT and (0.75mm) an external capacitor. 2mm 3mm DFN Package The LTC3873-5 is available in 8-lead ThinSOT and 2mm 3mm DFN packages. APPLICATIONS PARAMETER LTC3873 LTC3873-5 n Telecom Power Supplies + V UV 8.4V 4.1V CC n Automotive Power Supplies V UV 4V 2.9V CC n PoE Applications L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. No R and ThinSOT are trademarks of Linear Technology Corporation. SENSE All other trademarks are the property of their respective owners. TYPICAL APPLICATION High Ef ciency 5V Input, 12V Output Boost Converter Ef ciency and Power Loss vs Load Current 100 10000 1nF 90 4.7nF 80 RUN/SS 11.8k V IN I V TH CC 70 5V 1000 47pF 10F LTC3873-5 60 10H IPRG 50 V OUT 12V GND SW 40 12k 2A 100 V NGATE FB 22F 30 20 108k 38735 TA01a 10 0 10 10 100 1000 I (mA) OUT 3873 TA01b 38735fb 1 EFFICIENCY (%)LTC3873-5 ABSOLUTE MAXIMUM RATINGS (Note 1) V to GND Operating Temperature Range (Note 2) CC Low Impedance Source ........................... 0.3V to 9V LTC3873E-5 ......................................... 40C to 85C Current Fed ..........................................25mA Into V LTC3873I-5 ........................................ 40C to 125C CC RUN/SS ........................................................ 0.3V to 9V Junction Temperature (Note 3) ............................. 125C IPRG Voltage .................................0.3V to (V + 0.3V) Storage Temperature Range ................... 65C to 125C CC V , I Voltages ....................................... 0.3V to 2.4V Lead Temperature (Soldering, 10 sec) FB TH SW Voltage ................................................ 0.3V to 60V TS8 Package .....................................................300C PIN CONFIGURATION TOP VIEW TOP VIEW GND 1 8 NGATE IPRG 1 8 SW V 2 7 V FB CC I 2 7 RUN/SS TH 9 I 3 6 RUN/SS TH V 3 6 V FB CC IPRG SW GND 4 5 NGATE 4 5 TS8 PACKAGE 8-LEAD PLASTIC TSOT-23 DDB PACKAGE 8-LEAD (3mm s 2mm) PLASTIC DFN T = 125C, = 230C/W JMAX JA T = 125C, = 76C/W JMAX JA EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3873ETS8-5 PBF LTC3873ETS8-5 TRPBF LTCSP 8-Lead Plastic TSOT-23 40C to 85C LTC3873ITS8-5 PBF LTC3873ITS8-5 TRPBF LTCSP 8-Lead Plastic TSOT-23 40C to 125C LTC3873EDDB-5 PBF LTC3873EDDB-5 TRPBF LCSM 8-Lead (3mm 2mm) Plastic DFN 40C to 85C LTC3873IDDB-5 PBF LTC3873IDDB-5 TRPBF LCSM 40C to 125C 8-Lead (3mm 2mm) Plastic DFN LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3873ETS8-5 LTC3873ETS8-5 TR LTCSP 8-Lead Plastic TSOT-23 40C to 85C LTC3873ITS8-5 LTC3873ITS8-5 TR LTCSP 8-Lead Plastic TSOT-23 40C to 125C LTC3873EDDB-5 LTC3873EDDB-5 TR LCSM 8-Lead (3mm 2mm) Plastic DFN 40C to 85C LTC3873IDDB-5 LTC3873IDDB-5 TR LCSM 40C to 125C 8-Lead (3mm 2mm) Plastic DFN Consult LTC Marketing for parts speci ed with wider operating temperature ranges. *The temperature grade is identi ed by a label on the shipping container. For more information on lead free part marking, go to: