Hello,
I'm working with isolated DC-DC converter modules and have a question about their current handling capabilities.

While datasheets typically specify the maximum continuous output current, I don't see clear information about their tolerance for non-repetitive peak currents. like, how well do these modules handle short-term overcurrent situations, and is there a general rule of thumb or standard for determining the maximum allowable peak current?

Additionally, if a module features short-circuit protection with auto recovery, is it safe to assume it can withstand brief current spikes without sustaining damage? like for example a 5A current draw to charge the gate capacitor of a Mosfet.

Thanks in advance!

 

like for example a 5A current draw to charge the gate capacitor of a Mosfet.

That sort of short term current surge would come from the capacitors on the output. The power supply would likely not even notice it.

 

That sort of short term current surge would come from the capacitors on the output. The power supply would likely not even notice it.

Then what's the use of the 1W/2W dual output (15V / -3V) isolated DC-DC supply usually used with gate drivers. Is it just to power the high power side of the gate driver?

 

If the circuit is a flyback converter, then it will most likely have current mode control, so every cycle is current limited.

 

If the circuit is a flyback converter, then it will most likely have current mode control, so every cycle is current limited.

there is no mention in the datasheet or anywhere of the topology used for these Isolated Module DC-DC Converter

 

there is no mention in the datasheet or anywhere of the topology used for these Isolated Module DC-DC Converter

True, but if the output is regulated and the input is tolerant of a wide range of voltages then it's a safe bet that it is a flyback converter.

 

Then what's the use of the 1W/2W dual output (15V / -3V) isolated DC-DC supply usually used with gate drivers. Is it just to power the high power side of the gate driver?

* if I am understanding your concern correctly*

You are confusing two separate issues.
These dual voltage supplies are used for very high power IGBTs, which require a negative bias to properly turn off.
This fact doesn’t have a relationship with your original question, which is the current surge capability, which as Bob answered accurately, it is handled by the supply’s output capacitors.

If our answers don’t explain your concern, then explicitly indicate what issues you’re experiencing.

 

* if I am understanding your concern correctly*

You are confusing two separate issues.
These dual voltage supplies are used for very high power IGBTs, which require a negative bias to properly turn off.
This fact doesn’t have a relationship with your original question, which is the current surge capability, which as Bob answered accurately, it is handled by the supply’s output capacitors.

If our answers don’t explain your concern, then explicitly indicate what issues you’re experiencing.

Yes, Bob already explained that the surge needed to charge the internal parasitic caps of the mosfet comes from the output caps of the supply ..
Previously, I thought the dc dc module needs to supply the surge current to charge the mosfet gate caps (and thats in the Amperes range).. but now i just need to confirm whether the DC-DC module only needs to provide power for the gate driver IC!? so that i will be able to size it right ..

 

Yes, Bob already explained that the surge needed to charge the internal parasitic caps of the mosfet comes from the output caps of the supply ..
Previously, I thought the dc dc module needs to supply the surge current to charge the mosfet gate caps (and thats in the Amperes range).. but now i just need to confirm whether the DC-DC module only needs to provide power for the gate driver IC!? so that i will be able to size it right ..

No, not quite: the DC/DC converter has to supply the average current used to charge the gates plus the gate driver IC quiescent current.
The average current = Qg.f

 

No, not quite: the DC/DC converter has to supply the average current used to charge the gates plus the gate driver IC quiescent current.
The average current = Qg.f

Thank you Ian,
Now it's clear