Hey All,
I am new to implementing buck converter in a design. I recently used AP63356 in a design with the following specification:
Vin = 6V - 30V
Vout = 5.4V
Fsw 450 kHz
While testing the design I noticed the output voltage spikes of as high as 10V for a duration of 20-30 microseconds or so. This only seems to happen when there is sudden interruption of power to the buck converter for a short period.
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I am concerned that this could potentially damage the devices such as a microcontroller with absolute maximum voltage of 6V. I implemented this design by studying the typical application examples in the datasheet which does not show a need to add additional protection at the output.
I can Confirm this, these spikes have enough energy to kill sensitive MCU and similar devices.
From my experience, these look like control loop instabilities, caused by input voltage steps. Always take care to test your regulator circuis for such behaviour. Then take each useful measure to stop that. It might not just be layout or input voltage noise causing that, it's an intrinsic issue of the general control loop architecture - you may want to ask the manufacturer for support, or carefully read their app notes and datasheets - these should give you some valuable hints on their designs and how to use them in a successful manner.
If you want to learn something, go and study control loop theory at a university course - that's no simple matter that I'd be able to explain in a few words.
Schematic:
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I would love to know from those who are more experienced in buck converter design how big of the problem this is and what are the general design guidelines to mitigate suck output voltage spikes. As far asn the PCB layout is concerned I am aware that everything in the buck converter circuit should have as low imedance as possible.
Component placement:
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Layout:
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https://ibb.co/3kmVN64https://ibb.co/89DZ33fhttps://ibb.co/JKv7YCRhttps://ibb.co/wSdmTrP [ Attachment Invalid Or Does Not Exist ]
Thanks,
Kind Regards,
Sparsh
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