• State
  • +1 person also asked this people also asked this
  • Locked Locked
  • Replies 2 replies
  • Subscribers 99 subscribers
  • Views 207 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

AM62L: Capacitors for AM62L

Marinus Holzner
Intellectual 2110 points

Part Number: AM62L

Hi Sitara Team, 

Posting on customer behalv: 

For the CAP_VDDS_GENERAL1, CAP_VDDS_MMC0..2, and CAP_VDDS_GPMC pins, there is a small note in the data sheet at 5.3.20 Power Supply:

“There are three connection options if the respective VDDSHVx PIN is only operated at 1.8V. The pin can be connected to the same decoupling capacitor that is required for 3.3V operation, it can be left unconnected, or it can be Connected to the same 1.8V Power Source as the respective VDDSHVx PIN.”

Since the pins on this pcb at 1.8V, could I save myself on the capacitors on the CAP pins? Or could I connect the pins to the same 1.8V supply as the VDDSHVx pins? I guess there is an LDO hanging behind the pins that regulates to 1.8V, and the LDO becomes redundant if the supply is already 1.8V.

The only pin that could then be 3.3V would be VDDSHV3 for MMC1 as the SD card is attached here. Does I need only one capacitor at CAP_VDDSHV_MMC1, right? I think this is also described as follows: 

[FAQ] AM625 / AM623 / AM620-Q1 / AM62L / AM62Ax / AM62D-Q1 / AM62Px / AM64x / AM243x Design Recommendations / Custom board hardware design – Queries related to CAP_VDDSx CAP_VDDS - Processors forum - Processors - TI E2E support forums

 

Is that understanding correct? 

Thank you, 

Marinus 

  • 0
    TI__Guru**** 232565 points

    Hello Marinus 

    Thank you for the query.

    Marinus Holzner said:
    Since the pins on this pcb at 1.8V, could I save myself on the capacitors on the CAP pins? Or could I connect the pins to the same 1.8V supply as the VDDSHVx pins? I guess there is an LDO hanging behind the pins that regulates to 1.8V, and the LDO becomes redundant if the supply is already 1.8V.

    Please note that all the IOs in a IO group are expected to be connected to supply amplitude level that matches the dual-voltage IO supply for IO group Example VDDSHV0..VDDSHV4

    When any of the IO supply group VDDSHV0..VDDSHV4 are connected to 1.8V the relevant external capacitor connection is optional.

    Marinus Holzner said:
    The only pin that could then be 3.3V would be VDDSHV3 for MMC1 as the SD card is attached here. Does I need only one capacitor at CAP_VDDSHV_MMC1, right?

    You are correct.

    Regards,

    Sreenivasa

  • 0 in reply to Kallikuppa Sreenivasa
    TI__Guru**** 232565 points

    Hello Marinus 

    Although you did not ask, i included the information related to the internal LDO for SD card IO supply related information. Please note the below: 

    CAP_VDDSHV_MMC (1) CAP External capacitor connection for SDIO_LDO T16

    VDDA_3P3_SDIO PWR SDIO_LDO 3.3V analog supply U16

    This pin must always be connected via a 6.3V or greater, 3.3μF ±20% capacitor to VSS when the SDIO_LDO is being used to. This pin must always be connected via a 6.3V or greater, 3.3μF ±20% capacitor to VSS when the SDIO_LDO is being used to source VDDSHV3. The capacitor selected must provide a capacitance within the defined range after it has been derated for DC-bias, operating temperature, and aging effects. Otherwise, this pin may be connected directly to VSS when the VDDA_3P3_SDIO pin is also connected directly to VSS.

     Refer pin connectivity requirements 

    Regards,

    Sreenivasa