LM5180-Q1: Queries related to transient response

HI

1. feeback resistor is decide by turn ratio, Vout, Vd(diode votlage drop) and Rset(defaul it 12.1K), so it is fixed when you have fixed turn ratio and Vout

2. as the feedback is from primary, so effecitve way is adding more input and output capacitor

3. Rset is set a FB current level, for 12.1K, it is 100uA, which let the 100uA*Rfb=(Vo+Vd)*Nps=Vsw-Vin(when mosfet is on) , you can take it as reference 

Hi Daniel,

Thank you for the response. Can you please validate the design.

Hi

can I know the transformer inductance and turn ratio, and input range. the schematic is not very clear, I can see 120V diode for 12V  and 100V diode for-4V output, is that right?

Thanks

Hi,

Transformer parameters are as below. Input range is 9 -16V. Output +15V and -4V and  100mA each. Diode VR for 15V Output is 200V and -4V Output is 100V.

HI Yusuf:

thank you , let me check it and feedback to your later.

Hi Daniel,

We are using the flyback IC as gate driver secondary side power supply (Dual supply +15V and -4V for turn on and turn off of MOSFET). Since the load is not a constant one how to improve the load and line transient response.

Is there any specific recommendations you can provide which as to be taken care during the design and layout.

This is the switching waveform (at switch node pin 1) @ 100mA load. Kindly suggest how to reduce the overshoot and ringing.

Can I know how you test the waveform? is it the smallest test area at SW and GND?

Connected 100mA load at both output and probed across SW and GND.

Hi Daniel,

We performed load transient and found the output is not regulated. Can you please suggest the needful.

load is switching from 100mA to no load.