器件名称: DI-69
功能描述: 15 W Multi-Output DC-DC Converter
文件大小: 264.77KB 共2页
简 介:Design Idea DI-69 DPA-Switch 15 W Multi-Output
DC-DC Converter
Application VoIP Phone Device DPA424P Power Output 15 W Input Voltage 36-75 VDC Output Voltage 5 V / 7.5 V / 20 V Topology Forward
Design Highlights
Low component count Built-in accurate OV/UV with single resistor programming High efciency (88%) using synchronous rectication Multiple outputs with good cross-regulation Built-in output overload, open loop and thermal protection 400 kHz switching frequency No primary current sense resistor required
Capacitor C1, C2 and L1 provide line ltering. Resistor R2 programs the U1 current limit. The Q22 reected gate capacitance provides optimum reset for transformer T1. Zener VR1 clamps the peak drain voltage to a safe level during transient conditions. Resistors R21, R22, C21 and MOSFETs Q21 and Q22 form a capacitively coupled direct driven synchronous rectier for the main (5 V) output. Zener diode VR21 acts both as a clamp and as a diode to quickly recharge the Q21 drive capacitor C21. Resistor R23 holds Q21 off when no switching signal is present. The 20 V output is generated from a yback winding on the L2 inductor, which is rectied and ltered by diode D41 and C41. Zener VR31 and diode D32 provide a pre-load on the 7.5 V output to enhance regulation at light load.
D41 BAV19WS C41 4.7 F, 35 V VR31 D32 6.8 V IN4148
20 V, 10 mA J2-4
Operation
Resistor R1 programs the input under/over voltages to 33 V and 86 V. It also linearly reduces the maximum device duty cycle (D……