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WL1835MOD: WL1837MOD

Part Number: WL1835MOD
Other Parts Discussed in Thread: WL1837MOD

Dear Sir/Madam,

Due to component shortage, we have mix part# soldering (WL1835MOD & WL1837MOD) on a batch of PCB assemble on prototypes build.

Would like to confirm the below impedance behavior on ANT1 & ANT2 pins between WL1835MOD & WL1837MOD.

- WL1835MOD ANT1 & ANT2 pin to GND is 0ohm.

- WL1837MOD ANT1 & ANT2 pin to GND is Hi-Z.

Since don't have any RAW parts on hand, cannot verify above the impedance behavior is normal or not.

Not sure is it cause by the internal filter circuitry between Single Band (WL1835MOD) and Dual Band (WL1387MOD) application.

Need this information to confirm is there any PCBA issue (solder short or not soldering well).

Best regards,

Ping

  • Hi PingL,

    Are you asking about the RF pins impedance behavior if you GND them? Why would you GND these pins?

    BR,

    Seong

  • Hi Seong,

    No, I do not GND both RF pins on the prototype boards, just connect to U.FL connector for external antenna.

    I would like to know the integrated RF filter (Pi-filter or LC filter right behind the RF pins) is there any difference between WL1835MOD & WL1837MOD.

    I think TI does not release the Schematics / BOM for both modules.

    Best regards,

    Ping

  • Hi Ping,

    Unfortunately, I am unable to disclose any specific information about what is under the shield.

    BR,

    Seong

  • Hi Seong,

    I understand that TI is not willing to disclose all the technical things inside the shield.

    But I hope you can reply simple questions below, is really helpful to decide soldering is good or not.

    I am facing trouble with different combinations of Open and Short symptoms on ANT1 & ANT2 pins after PCBA. I really need this basic characteristic to decide soldering rework or not before ship those prototype boards to our customer.

    By using DMM (resistance mode) to measure ANT1 & ANT2 pin reference to GND.

    - Measure WL1835MOD ANT1 (ANT2) pin to GND is 0 Ohm or Open?

    - Measure WL1837MOD ANT1 (ANT2) pin to GND is 0 Ohm or Open?

    Best regards,

    Ping

  • Ping,

    I'm not sure if I understand the question. Could you please be more specific? 

    In any event, the best way to confirm would be to inspect the solder joints under the module by x-ray.

    BR,

    Seong

  • Hi Seong,

    Today I received few pieces of WL1835MOD from our customer.

    From the raw material, we inspect ANT1 & ANT2 pin connectivity at the bottom side, both RF pins reference to GND is 0 Ohm.

    Could you confirm is it normal on WL1835MOD? or is an issue with raw materials need to proceed RMA?

    Best regards,

    Ping

  • Hi Ping,

    The difference between the two modules' RF_ANT1 pin:

    1. WL1835MOD - this pin is directly tied to the output of a 2.4GHz band pass filter
    2. WL1837MOD - this pin is directly tied to the output of a 2.4/5GHz diplexer

    I am not certain what to expect when measuring the resistance of these pins with respect to GND. And unfortunately, I do not have these modules on-hand to reproduce what you are reporting.

    In any event, there should not be any problems as long as you follow the Baking and SMT Recommendations stated in the datasheet (which is the same between WL1835MOD and WL1837MOD).

    BR,

    Seong