深圳市丰胜达电子商行 （非本站正式会员）

     Manufacturer:RENESAS
Description:Cycle-by-cycle current limiting prevents the primary current from reaching destructive levels, whereas the fault integration feature provides hiccup fault protec- tion. For a continuous short circuit at the output, the MAX5069s fault integration feature provides hiccup fault protection. This greatly minimizes destructive tem- perature rise during persistent overload conditions. Pin 8 of the MAX5069A, capacitor C11, and resistor R9 form the fault integration circuit. Current-sense resistors R14 and R15 sense the current through the primary of transformer T1 and turn off the respective MOSFET (N1 or N2) that is switching when the trip level of 314mV (typ) is reached. The planar surface-mount transformer features a bias winding that, along with diode-pair D2, D3, and inductor L2, provide full-wave rectification for the bias voltage powering the MAX5069A once the input voltage is stable. Upon initial input-voltage application, bootstrap resistor R10 and reservoir capacitor C9 enable the MAX5069A to startup within approximately 200ms. The transformer uses a secondary-side center tap and dual Schottky diode D1 to provide full-wave rectification for reduced output-volt- age ripple. When either MOSFET is turned off and the alternate turned on, both D1 diodes are conducting. The transformer provides galvanic isolation up to 500V. Resistor R21 and capacitor C24 form a snubber network that suppresses transient overvoltage ringing at diode D1 caused by transformer T1 leakage inductance and diode D1 junction capacitance. On the transformers secondary side, a 0.6V shunt reg- ulator (MAX8515, U3) along with feedback resistors R1 and R2 provide secondary-side voltage feedback through optocoupler U2 to the primary side. The MAX5069A receives the voltage feedback signal on the primary side from biasing resistors R16, R17, R18, and optocoupler U2.