Tool/software:
Hi team,
My customer is using UCC27524A and output RMS current is 340mA. Peak current is about 1A.
Datasheet shows that continues current is 0.3A max and peak current is 5A within 0.5us.
Q1: 340mA AC RMS is ok for 0.3A max?
Q2: 1A/0.6us peak is ok for 5A/0.5us?
Are there any risk under this use case?
Zoom in figure1
zoom in figure 2
Hi Gary,
For Q1, 340mA AC RMS is not going to work for the 0.3A max because 340mA is breaking the specs. You should get the RMS/avg current down to below 0.1A per channel.
From looking at your waveforms, there seems to be ringing before the actual peak current, and ground bouncing from the yellow and green channels. It is unclear whether your undershoot is within specs, so can you please send another waveform that is zoomed in on these spikes:
For Q2, 1A/0.6us peak is sufficient for 5A/0.5us. The absolute maximum ratings, 5A, 12V, and .5us, determine the total energy that can be handled by calculating 5A*12V*0.5us = 30uJ. As long as the changes made are under 30uJ and 5A (at 12 VDD), the IC should be able to handle it.
In addition, could you clarify which channel is for which pin measurement and if the current waveform is measuring one or both channels? What is the application of UCC27524A? Could you send a schematic of this application?
Thanks,
Suzuko
Hi Suzuko,
Thanks for your reply.
What is the failure type if they insist this usage. Thermal issue? EOS? IC damage?
Hi Gary,
For that rippling current and overshoot/undershoot question, it would be an EOS (electrical overstress damage) if they insist the usage (high RMS current, overshoot, undershoot).
To make adjustments in case of output EOS, you might want to add gate resistor placeholders at OUTA and OUTB.
Also, can you send a more zoomed in picture of the overshoots/undershoots?
Thanks,
Suzuko
Hi Suzuko,
Customer submitted a FA report and the result shows Electrically Induced Physical Damage. PIN6(VDD) in short to GND.
Customer want to know if this issue is relevant to that FA case. Will this OC EOS have a effect on VDD？
Customer want to increase the OC and want to artificially damage the VDD. Can you do it on your side or do you have any suggestions, like increasing the cap value?
What is the series resistor value you recommend to add? 10ohm or 33ohm？
Hi Gary,
What is your QEM #? You are experiencing a short from VDD to GND because you are experiencing overshoot and undershoot. To manage this, I recommend starting with a small resistor like 1ohms and then increasing the value.
What is the intention behind destroying the VDD? For the capacitors, are you referring to C54 and C55?
Thanks,
Suzuko
