POWER LOSS (W) LTC3805-5 Adjustable Frequency Current Mode Flyback/ Boost/SEPIC DC/DC Controller FEATURES DESCRIPTION n V and V Limited Only by External Components The LTC 3805-5 is a current mode DC/DC controller de- IN OUT n 4.5V Undervoltage Lockout Threshold signed to drive an N-channel MOSFET in flyback, boost n Adjustable Slope Compensation and SEPIC converter applications. Operating frequency n Adjustable Overcurrent Protection with Automatic and slope compensation can be programmed by external Restart resistors. Programmable overcurrent sensing protects n Adjustable Operating Frequency (70kHz to 700kHz) the converter from overload and short-circuit conditions. With One External Resistor Soft-start can be programmed using an external capacitor n Synchronizable to an External Clock and the soft-start capacitor also programs an automatic n 1.5% Reference Accuracy restart feature. n Only 100mV Current Sense Voltage Drop The LTC3805-5 provides 1.5% output voltage accuracy n RUN Pin with Precision Threshold and Adjustable and consumes only 360A of quiescent current during Hysteresis normal operation and only 40A during micropower start- n Programmable Soft-Start with One External Capacitor up. Using a 9.5V internal shunt regulator, the LTC3805-5 n Low Quiescent Current: 360A can be powered from a high V through a resistor or it IN n Small 10-Lead MSOP and 3mm 3mm DFN can be powered directly from a low impedance DC voltage from 4.7V to 8.8V. APPLICATIONS The LTC3805-5 is available in the 10-lead MSOP package n Automotive Power Supplies and the 3mm 3mm DFN package. n Telecom Power Supplies L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered n trademarks, No R and ThinSOT are trademarks of Linear Technology Corporation. Isolated Electronic Equipment SENSE All other trademarks are the property of their respective owners. n Auxiliary/Housekeeping Power Supplies n Power over Ethernet TYPICAL APPLICATION 5V to 12V/1A Boost Converter Efficiency and Power Loss vs Load Current 100 2.5 UPS840 4.3H V OUT V IN 12V 95 2.0 5V EFFICIENCY 5V 22F 1A 100F 8.5V EFFICIENCY 2 V CC RUN GATE 90 1.5 LTC3805-5 1.33k 8.5V LOSS 5V LOSS I OC TH 3k 85 1 191k SSFLT I SENSE 0.1F 20k FS FB 80 0.5 SYNC GND 470pF 118k 8m 13.7k 38055 TA01a 75 0 1 0.01 0.1 10 LOAD CURRENT (A) 38055TA01b 38055fe 1 EFFICIENCY (%)LTC3805-5 ABSOLUTE MAXIMUM RATINGS (Note 1) V to GND OC, I .................................................... 0.3V to 1V CC SENSE Low Impedance Source ........................ 0.3V to 8.8V Operating Junction Temperature Range Current Fed ........................................25mA into V * (Notes 2, 3) ........................................... 55C to 150C CC SYNC ........................................................... 0.3V to 6V Storage Temperature Range ..................65C to 150C SSFLT........................................................... 0.3V to 5V Lead Temperature (Soldering, 10 sec) FB, I , FS ................................................. 0.3V to 3.5V MSE Package ....................................................300C TH RUN ........................................................... 0.3V to 18V *LTC3805-5 internal clamp circuit regulates V voltage to 9.5V CC PIN CONFIGURATION TOP VIEW TOP VIEW SSFLT 1 10 GATE SSFLT 1 10 GATE I 2 9 V TH CC I 2 9 V TH CC 11 11 FB 3 8 OC FB 3 8 OC RUN 4 7 I SENSE RUN 4 7 I SENSE FS 5 6 SYNC FS 5 6 SYNC MSE PACKAGE 10-LEAD PLASTIC MSOP DD PACKAGE T = 125C, = 45C/W JMAX JA 10-LEAD (3mm 3mm) PLASTIC DFN EXPOSED PAD (PIN 11) IS GND, MUST BE CONNECTED TO GND T = 125C, = 45C/W JMAX JA EXPOSED PAD (PIN 11) IS GND, MUST BE CONNECTED TO GND ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3805EMSE-5 PBF LTC3805EMSE-5 TRPBF LTDGX 10-Lead Plastic MSOP 40C to 85C LTC3805IMSE-5 PBF LTC3805IMSE-5 TRPBF LTDGX 10-Lead Plastic MSOP 40C to 125C LTC3805HMSE-5 PBF LTC3805HMSE-5 TRPBF LTDGX 10-Lead Plastic MSOP 40C to 150C LTC3805MPMSE-5 PBF LTC3805MPMSE-5 TRPBF LTDGX 10-Lead Plastic MSOP 55C to 150C LTC3805EDD-5 PBF LTC3805EDD-5 TRPBF LDHB 10-Lead (3mm 3mm) Plastic DFN 40C to 85C LTC3805IDD-5 PBF LTC3805IDD-5 TRPBF LDHB 10-Lead (3mm 3mm) Plastic DFN 40C to 125C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on lead based finish parts. For more information on lead free part marking, go to: