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LMG1210: Only bottom channel is working, top channel gives zero output (Counterfeit?)

Kawsar Ali
Intellectual 320 points
Part Number: LMG1210

Hi,

I have followed LMG1210EVM-012 (SNVU572) to design some DCDC converters and they were all working fine until recently when I had some over-current failure of the GaN chips that took away the LMG1210 drivers with them. Due to the ongoing global chip shortage, I had to source the LMG1210 drivers from some vendor on eBay who charged me a whooping £20 per chip! I was desperate, so I paid for that and got some from them. But unfortunately, I have not had success with one single chip out of 5 yet. I have replaced every component on that reference design (SNVU572) with new components just to make sure that the source of error is the driver chip itself. I am getting normal output from the bottom channel, but a flat zero from the top channel. The voltage across the bootstrap cap is fine at about 6V.

I have doubts that these chips from the vendor are counterfeit, but I can not prove that conclusively yet. So I thought I shall ask here.

Markings on the previously working chips (sourced from Digikey):

LMG1210

TI 9BJ

PFTX

Markings of the new chips (sourced from eBay):

LMG1210

TI 88J

PDC4

Can someone please comment on whether I am missing something technical here, or the chips are faulty? Thank you.

  • 0
    TI__Genius 9431 points

    Hello,

    6V across the bootstrap cap is too high. The recommended max from HB to HS pins is 5.25V. 

    TI recommends submitting purchasing from TI authorized distributors or from TI directly. Due to uncertainties in the supply chain regarding chain of custody of the products, TI does not provide warranty coverage or customer support for semiconductor products purchased outside of its authorized sources. All other verification requests must be worked through their supply chain: http://www.ti.com/support-quality/quality-policies-procedures/anti-counterfeit.html

    If you suspect that you have counterfeit parts, please create a new case following the instructions in the link.

    Best regards,

    Leslie