• State Resolved
  • Locked Locked
  • Replies 9 replies
  • Answers 1 answer
  • Subscribers 78 subscribers
  • Views 1054 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

MSP430FR5994: MSP430FR5994 Launchpad Layout appears inconsistent with Schematic

James Nadir
Expert 1120 points
Part Number: MSP430FR5994

Hello All,

The Gerber Layout appear inconsistent with the schematic representation wrt to the Micro SDCard.

  1. The pdf schematic (2nd image below) shows that the P2.7_SD_Detect signal is attached to a "pin B" of the device. The layout gerbers show P7.2_SD_Detect  connected to pin 4. The datasheet for the SDCard (Molex) does not provide a circuit diagram for the 10 pin part so  I do not know what functions pin A and pin B provide.  Can anyone help here and explain this apparent inconsistency.  
  2. Pin A is grounded on the schematic. The Gerber files show a grounded landing pad next to the R7 resistor which connects to the SD socket. Is that pin A? 
  3. From the Gerbers, it appears that the case is not grounded. 
  4. And can anyone tell me why is there an opening in the Top Metal (green) under the SDCard socket?   

thank you for any help

jjim

  • 0
    Expert 1120 points

    I found some additional information about the Molex micro SD Socket. Pin A and Pin B are the switch nail (SW / Pin A ) and  detect nail (DN / Pin B). They are the two terminals of open/close contact. P7.2_SD_DETECT is connected to SW which is Pin B. The other terminal in pin A  (DN) is GND. So nothing is inconsistent, it just took me awhile to figure out.  

    I still don't know why there is a hole in the GRD fill under the micro SD socket though....

    thanks to everyone who took the time to read this.

    jim

  • 0 in reply to James Nadir
    TI__Genius 13215 points

    Hi,

    Thanks for feedback with resolving the question. I will try to check you additional question and reply you shortly.

  • 0 in reply to James Nadir
    TI__Genius 13215 points

    Hi James,

    Could you point out which hole under the micro SD socket you are concerning? Do you mean the three holes I marked below?

  • 0 in reply to Wei.Jetim Zhao
    Expert 1120 points

    Hello Wei

    I apologize for my poor choice of wording. I did not mean hole as in via hole (made with a drill) but  the missing rectangle of the top layer metal just above the silk screen image of the jumping lamb(?). 

    thanks

    jim

     

  • 0 in reply to James Nadir
    TI__Genius 13215 points

    Hi jim,

    This is rectangle?

  • 0 in reply to Wei.Jetim Zhao
    Expert 1120 points

    yes, that the one.

    thanks

    jim

  • 0 in reply to James Nadir
    TI__Genius 13215 points

    Hi James,

    I import the layout file to Altium Designer 18 to open it. The rectangle seems to be part of the footprint of micro SD card connector, so that the poly keep the rectangle out. The rectangle information(LOT NO) on the same location of the connector could be found on the package file of the component(CONN MICRO SD R/A PUSH-PUSH SMD, Digikey WM19092CT-ND).

  • 0 in reply to Wei.Jetim Zhao
    Expert 1120 points

    Hello Wei

    I know that the keep out is part of the footprint and is in the manufacturer's package specification. I think (but not sure) that your image is the top (so the lot number would be visible). I attached a diagram of what I believe is the bottom and faces the PCB when mounted.   The red box and arrow are my additions showing the keep out area. The keep out area appears to be around some squares (no idea what these are - contact springs maybe). But I could not find an explanation or reason. With the Epson crystal the manufacturer states that the keep out is needed to prevent interference between a signal and crystal operation. But there is no such specification for the micro SD card socket. If you look at the Gerber files of the MSP430FR5994 launchpad layout you will see that all 4 layers are kept out from under the crystal. But this is not the case for the micro SD card socket, only the top metal is kept out which is puzzling.  The only reason I could imagine is that if the squares in the keep out region are exposed electrical connections then it would make sense to keep out anything that might short them (i.e. as though the micro SD card was attached to a copper plate). But this is conjecture on my part.

    I could not find an electrical specification for the micro SD card from the manufacturer that might explain the rationale for the two keep out rectangles. Do you have the electrical specifications that you could share?

    thanks

    jim

  • 0 in reply to James Nadir
    TI__Genius 13215 points

    Hi Jim,

    Yes, you are right about the bottom of the SD card package, as you were showing.  I would agree that the keep out area is for the squares.

    But I'm sorry I don't have the additional electrical specification for the micro SD card connector rather than the datasheet you were showing.

**Attention** This is a public forum