LR2257 - LRC

LR2257 AC/DC Current Mode PWM

Pin Symbol Pin Description 1 FB Feedback input 2,3 NC Test Pin * 4 VDD Power Supply 5,6 SW Power Transistor output 7,8 GND Ground *Note: Test2 should connect to Test3 while in application 2/9 + - LO HI Working Principle HI HV DC LO 1M GND SW LR2257 12 3 4 PC817A 12 56 7 8 LESHAN RADIO COMPANY, LTD. LR2257 1 T=114 2 1 1N5817 T=8 2 1 T=2.

Features

of over current and over voltage protection mechanisms Delivering up to 3W yet consumes, the typical application of the device will include: z Battery Charger, such as handset phone z Power Adapter z Offline Power Generator z Etc. ¾ Lowest Total Cost Solution ¾ Low Power for Green Environments Protection, as lower as 0.3W ¾ Current Mode PWM ¾ Over-Current Protection, Over and Under-voltage Protection ¾ Emitter Drive of Internal Power Transistor ¾ 65kHz Switching Frequency Absolute Maxim Ratings Item Power Supply FB Start Voltage FB Under-voltage Threshold FB Clamp Voltage FB input current S.