SC4808BIMSTRT Semtech

SC4808A/B High Performance Dual Ended PWM Controller POWER MANAGEMENT Description Features The SC4808A/B is a dual-ended, high frequency, integrated 120A starting current PWM controller, optimized for isolated applications that Pulse by pulse current limit require minimum space. It can be configured for current Programmable operation up to 1MHz or voltage mode operation with required control circuitry Internal soft start where secondary side error amplifier is used. Programmable line undervoltage lockout Over current shutdown Some of the key features are high frequency operation of Dual output drive stages on push-pull configuration 1 MHz that allows the use of smaller components thus Programmable internal slope compensation saving cost and valuable board space. An internal ramp Programmable mode of operation (peak current mode on the Current Sense pin allows Internal Slope or voltage mode) Compensation programmed by an external resistor. Other External frequency synchronization features include programmable frequency up to 1MHz, Pulse by Pulse current and Line Monitoring Input with Bi-phase mode of operation Hysteresis to reduce stress on the power components. -40 to 105 C operating temperature 10 Pin MSOP lead free package available. WEEE and A unique oscillator is used to synchronize two SC4808s to RoHS compliant. work out of phase. This minimizes the input and output ripple thus reducing noise on the output line and reducing Applications stress and size of input/output filter components. The dual Telecom equipment and power supplies outputs can be configured in Push-Pull, Half Bridge and Networking power supplies Full Bridge format with programmable dead time between Industrial power supplies two outputs depending on the size of the timing Push-pull converter components. Half bridge converter Full bridge converter The SC4808 also features a turn on threshold of 12V for SC4808A and 4.4V for SC4808B. They are available in Isolated VRMs MSOP-10 packages. Typical Application Circuit Vo Vin Gnd Out RSENSE Gnd In OUTA RC OUTB REF CS VCC FB SYNC SYNC LUVLO GND SC4808 Revision October 20, 2005 1 www.semtech.comSC4808A/B POWER MANAGEMENT Absolute Maximum Ratings Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not implied. Plarameter SmymboMsaximu Unit SVupply Voltage -V0.5 to18 CC SIupply Current 2A0 m CC SYNC, RC,CS, LUVLO, REF to GND -V0.5 to 7 FVB to GND -0.5 to (V+V0.5) FB REF RIEF Current 1A0 m REF OVUTA/OUTB to GND -V0.5 to 18 OUTA/B OIUTA/OUTB Source Current (peak) -A250 m source OIUTA/OUTB Sink Current (peak) 2A50 m sink Power Dissipation at T=P25C 1W.105 A D Thermal Resistance 1W13.1 C/ JA JTunction Temperature -C40 to 150 J STtorage Temperature Range -C65 to 150 STG LTead Temperature (Soldering) 10 Sec. +C300 LEAD EVSD Rating (Human Body Model) 2Vk ESD Electrical Characteristics Unless specified: VCC = 12V CL = 100pF T = -40C to 105C A Psarameter Tnest Condition Mpi Txy Mta Uni PWM M,aximum Duty Cycle Fosc = 50kHz, FB = 5V 498 405% Measured at OUTA or OUTB M,inimum Duty Cycle Fosc = 50kHz, FB = 1.5V 0% Measured at OUTA or OUTB Current Sense Gain 3 Maximum Input Signal 4575 552 5V7 m CS to Output Delay 1s00 n Over Current Threshold .0850 .195 V Internal Slope Compensation 2k5 Resistor FB to CS Offset 10.3010.5 1V.7 Output OUT Low Level 00.05 .V7 OUT High Level 151.0101.2 1V2.0 Rise Time 2s5 n Fall Time 2s5 n 2005 Semtech Corp. 2 www.semtech.com