CS51221

CS51221 CS51221 Enhanced Voltage Mode PWM Controller 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 (1nF 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 10 100 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 330pF 0.01µF 200 2200pF 4.3k D11 BAS21 100pF COMP VFB RT/CT SYNC SS LGnd 680pF D13 V33...