CS51221 Datasheet | Cherry Semiconductor Corporation

Description The CS51221 fixed frequency feed forward voltage mode PWM controller contains all of the features necessary for basic voltage mode operation. This PWM controller has been optimized for high frequency primary side control operation. In addition, this device includes such features as: Soft Start, accurate duty cycle limit control, less than 50µA startup current, over and under voltage protection, and bidirectional synchronization. The CS51221 is available in 16 lead PDIP and SO narrow surface mount packages. s s Features 1MHz Frequency Capability Fixed Frequency Voltage Mode Operation, with Feed Forward Thermal Shutdown Under Voltage Lock-out Accurate Programmable Max Duty Cycle Limit 1A Sink/Source Gate Drive Programmable Pulse by Pulse Over Current Protection Leading Edge Current Sense Blanking 75ns Shutdown Propagation Delay Programmable Soft Start Under Voltage Protection Over Voltage Protection with Programmable Hysteresis Bidirectional Synchronization 25ns GATE Rise and Fall Time (1n F load) 3.3V 3% Reference Voltage Output s s s s s s s Application Diagram 36V-72V to 5V/5A converter s s s s s BAS21 VIN (36V to 72V) 51k FZT688 11V 1µF 22µF 18V 160k T3 100:1 0.1µF 24.3k VC VREF VCC UV OV ISET FF GATE ISENSE U1 s T2 2:5 VOUT (5V/5A) 100µF SGnd 510k 10k T1 4:1 MBRB2545CT 10 CS51221/2 0.22µF 10k 1µF SYNC 330p F 0.01µF 200 2200p F 4.3k D11 BAS21 100p F P VFB RT/CT SYNC SS LGnd 680p F D13 V33MLA1206A23 20.25k 13k 10 IRF634 Package Options 16 Lead SO Narrow & PDIP GATE ISENSE PGnd 470p F VC PGnd VCC VREF LGnd SS P VFB 0.1µF 5.1k SYNC 2k 5.6k 180 1k TL431 2k 150 4700p F MOC81025 FF UV OV RTCT ISET 1k Cherry Semiconductor Corporation 2000 South County Trail, East Greenwich, RI 02818 Tel: (401)885-3600 Fax: (401)885-5786 Email: info@cherry-semi. Web Site: .cherry-semi. Rev....