why inductor burn out in the coax circuit of IMX6D?

[翔李]

HI,

I debug a IMX6D board,includes a MAX9286 IC to capture 4coax camera 720P25 video in,connect to imx6d by mipi.The camera is powered by the coax calbe means that the cable supply power and video at the same time.

It works well when use VDD_CAM 5V power supply to the coax cable,but when use 12V supply,the inductor 330NH burned out usually.Each camera is 100mA at 12V,150mA at 5V.

As following picture,the burned out inductor L69 in the red part ,and the OK inductor in the green partL69 is ,.LQW18CNR33J00 330NH,630mA.

Why do the inductor L69 burn out? How to debug it?

[Pavel]

It looks like that there is a resonance problem for your inductor of 330nH and capacitor of 0.22uF. See the following page:

https://en.wikipedia.org/wiki/LC_circuit

Resonance frequency for this circuit is near to 6MHz.

Change capacitor or inductor on your board.

Have a great day,
Pavel Chubakov

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[翔李]

Thanks.

why 5V supply is ok,but 12V burn out L,while the resonance is 6MHZ?

and what is suitable value of capacitor if I like to change capacitor .