Questions and discussions about the hardware aspects of the TD RF modules, boards and accessories.
ramon2015
 
Posts: 51
Joined: Mon Jul 06, 2015 4:06 pm

ESD protection for the antenna - BOM?

by ramon2015 Tue Nov 10, 2015 5:54 pm

Hello,

I would like to know the part number of the SMD ESD protection for the antenna.

By the way, Is there any BOM of the EVB, so we can use the part numbers from the EVB?

I am currently using the TD1208 EVB.

How does the ESD impact on the 50ohm antenna impedance?
I think I should include it into my matching network, so the RF pin sees 50 ohm including the ESD. what do you think?

Regards, Ramon.
yluque
 
Posts: 3
Joined: Tue Nov 03, 2015 12:51 pm

Re: ESD protection for the antenna - BOM?

by yluque Thu Nov 12, 2015 8:15 am

Dear Ramon,

You can use « ESDA-MLP7 » SMD ESD reference.
This reference, dedicated for RF application, have low capacitance in order to avoid antenna mismatching.

Best regards,

Yohann Luque
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mstempin
 
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Joined: Thu May 07, 2015 9:24 am

Re: ESD protection for the antenna - BOM?

by mstempin Thu Nov 12, 2015 8:42 am

Hi Ramon,

The recommended reference to use is documented in the TD1208 datasheet on page 16, just below the typical application diagram: it is an ESD9R3.3ST5G (On Semiconductor).

This part is designed for RF applications and features an ultra-low capacitance (0.5pF typical), which should not change the nominal 50 ohms impedance.

It is important to add an ESD protection if you have an antenna connector that is accessible by the user like on the TD EVB boards, but it is always a good thing to add one even if the antenna is internal for clamping over-voltages (> 6V) that may be induced in the antenna by nearby thunderstorms, that may destroy the input RF LNA.
ramon2015
 
Posts: 51
Joined: Mon Jul 06, 2015 4:06 pm

Re: ESD protection for the antenna - BOM?

by ramon2015 Tue Feb 09, 2016 12:09 pm

Hi,

Thanks for your answer.

I have acquired the ESD9R3.3ST5G and it is very small (SOT-923) and thus very hard to solder properly.
Having a look at the EVB I have seen you assembly another ESD protection (0603ESDA-MLP), which has a 0603 footprint.

Do you still recommend the ESD9R3.3ST5G rather than the 0603ESDA-MLP?

Regards, Ramon.
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mstempin
 
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Re: ESD protection for the antenna - BOM?

by mstempin Tue Feb 23, 2016 2:24 pm

Yes, the ESD9R3.3ST5G has better performance than the 0603ESDA-MLP, but you can use both. The important thing is to use a special purposed RF ESD devices here with very small capacitance values, not general purpose ones, as they will influence the antenna matching.
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