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LDC2114EVM: LDC211X Coil schematic consult

Part Number: LDC2114EVM
Other Parts Discussed in Thread: LDC2114

Hello

This is Fang from GREE in Zhuhai city.

EVM211X and Coil sample are used, but I found COM pin and IN pin is connecting in schematic (Doc :SNOU146A-January 2017- Revised July 2017), as below.

My question are :

1. Why they are connecting , I think they should be opened .The input and ouput of coil are between COM and IN (picture 2 )

2. What are the 1K resister and Jumper used for if COM and IN connecting .

Thank you so much

BR

  • Hello,

    Can you reattach your pictures? I'm not able to view them.

    In general, INx and COM are shorted in the schematic because this will form the coil in the layout. We know that the spiraled trace forms an inductor, but the layout tool sees it as a short. 

    Best Regards,

  • Hello,

    EVM211X and Coil sample are used, but I found COM pin and IN pin is connecting in schematic (Doc :SNOU146A-January 2017- Revised July 2017), as picture 1 .

    My question are :

    1. Why they are connecting , I think they should be opened .The input and ouput of coil are between COM and IN (picture 2 )

    2. What are the 1K resister and Jumper used for if COM and IN connecting in picture 1 ?

    Thank you so much

    picture1

    picture 2

  • Upload the pictures again.

    picture 1

    picture 2

  • Hello,

    INn and COM must be shorted in the schematic in order to construct the PCB coil. The coil is not a surface mount component; it is made of a single spiraled trace. In order to create the coil in the PCB layout with a single trace, the INn and COM pins must be shorted in the schematic. 

    The 1kohm resistors are added so that the Rp value of the coils does not exceed the maximum Rp value that the LDC2114 can drive (10kohms). Additional series resistance decreases Rp.

    Best Regards,