Fusible resistor damage

Hi,
Thank you for using power integrations product.
Can you provide me the schematic and the inrush current waveforms?
What is the output voltage and current of this design?
usually we can use both, ntc and fuse in the same design

Hi,
Thank you for using power integrations product.
Can you provide me the schematic and the inrush current waveforms?
What is the output voltage and current of this design?
usually we can use both, ntc and fuse in the same design

Thanks for reply.
actually i am asking for can we use fusible resistor and NTC in series not NTC & fuse.
What happens if Fusible resistor replaced by NTC?
output voltage and currents are
24V@ 0.150A
5V@ 0.250A
5V@ 0.250A
Actually waveforms are not available. Readings observed using DMM.

Hi,

Most of the design uses NTC in series with Fuse. Usually Fusible resistors will already limit current surge in the circuit

Few tips:

The Inrush current is limited by the impedance of the input loop, that is the NTC, any series resistance ,DC resistance of the inductor (CMC\differential choke), trace resistance and the ESR of the input capacitors.

As a quick calculation, The maximum inrush current is equal to the maximum peak voltage divided by the impedance or resistance. To make it simpler, majority of the resistance will come from the NTC if there are no other series resistors. Hence, the formula is Vinput(peak)/NTC resistance.

For Fusible resistor, its similar Vpeak/Rf, this current should not exceed the maximum pulse current rating (or maximum instantaneous Power) of the resistor.