L7987 ripple issue

[PZha.1]

HI Sir，

we have two different results of the ripple noise

base on same PCBA design, but different L7987 origin:

1. Mark of "ST e3 G9207，L7987， CHN 3L0"，ripple noise 2.2V 2.9KHz

input 24V， output 12V， load 5ohm 2.4A

2. Mark of "ST e3 7B658， L7987， PHL 037"，ripple noise 0.04V 

input 24V， output 12V， load 5ohm 2.4A

the image of the chip and the image of the ripple see below.

why is it like that, it make no sense，

could you please advise.

thanks.

with best regards,

PZha

L7987 CHN 12V 2.5A, 24V inL7987 PHL 12V 2.5A, 24V inL7987 CHNL7987 PHL

[Peter BENSCH]

The logo on the CHN looks very mysterious, so you should check the origin of this chip carefully. If the supplier cannot provide a Bulk ID, it is probably a fake.

If you have the Bulk ID, please do not post it here due to the risk of misuse, but have it checked by Online Support OLS.

Regards
/Peter

[PZha.1]

HI Peter，

thanks for your support.

how to find out what the marking "ST e3 G9207，L7987， CHN 3L0" means.

thanks.

with best regards,

PZha

[Peter BENSCH]

It doesn't say 3L0, but 310, which would actually stand for the date code. But as mentioned, I suspect a counterfeit component, which can be recognised by the bulk ID.

[PZha.1]

HI Peter，

thanks for your reply,

some packaging materials no longer exist,

but we have marked the D/C in our ERP system,

could you please send us the instruction for the logo.

appreciated.

with best regards,

PZha

[Peter BENSCH · Accepted solution]

Without at least the Bulk ID, it is no longer possible to determine whether the devices are originals without destructive testing, the file codes are not sufficient for this. However, you can contact your supplier and ask for proof of originality.

Regards
/Peter