LM5007: LM5007, short on Vin, 50ms startup delay ?

Hello Edgar

Would you please share the schematic? Also, label CH1, CH2, CH3 and CH4 ? I guess CH1 is VIN, CH2 is load current ..........

-EL 

Dear Eric,

CH1 is Vin, 
CH2 is LM5007 output

CH3 is 3.3V (wich shutdown if we don't have enough capacitor as output)

CH4 is Vin current (short circuit)

the CH1 blue curve represent the voltage input of lm50007 which we short thus leading to 0V (approx) during the time the fuse blow up.

Hello Edgar 

Looks like you have to measure the V(C81), V(C75), V(C53) together with the VIN node which you mentioned. Please share the waveform when it is ready. 

It is not recommended discharging the energy stored in the output capacitor through the internal high-side power MOSFET. The IC can be damaged if an excessive current flows back from the output capacitor. 

-EL  

Hi El,

On my picture, Vin is VC53 (dark blue) and VC81 is the cyan curve. VC75 is close to VC81.

indeed, the trick was to reduce C81 value to lower caapcitance to reach under 2V at the SW pin in a faster way thus enabling the start of the IC again