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LP-AM263: Launchpad Power Source from BoosterPack

Abdul Razak
Prodigy 135 points

Part Number: LP-AM263
Other Parts Discussed in Thread: TPS22965, LP-AM243

we are interfacing AM263 Launchpad with our Board.

whether it is possible to power ON the Launchpad with External Power Supply through BoosterPack Pin's (+5V >>J3.21 and J7.61)
This is to avoid the external power adapter (Through Type-C) of Launchpad.

also confirm attached documents are the one to refer for LP-AM263

in User guide J6.55 is SPI0 in Figure 4-24. AM263x LaunchPad BoosterPack Pinout and SPI1 in "Table 4-24. Pinmux Options for J6"

https://www.ti.com/lit/zip/sprr433 schematic "PROC111E2(001)_Sch"

LP-AM263- user guide.pdf

  • 0
    TI__Mastermind 18760 points

    Hi, 

    Please see my answers below: 

    Abdul Razak said:
    whether it is possible to power ON the Launchpad with External Power Supply through BoosterPack Pin's (+5V >>J3.21 and J7.61)
    This is to avoid the external power adapter (Through Type-C) of Launchpad.

    That was my initial design intent. However...

    • One problem might be the TPS22965 power switch I used to gate USB-C 5.0V to the VSYS_5V0. The datasheet states that the output it set to GND when the ON input is held LOW. It might mean held to GND through the leakage of the low-side FET (see 9.2 Functional Block Diagram), but there is also a separate component in the same family called TPS22965N which explicitly states that the output is OPEN when ON is held LOW. 
    • I also noticed that a few pull-up lines on POR, RESET and enable lines coming from the Test Automation Header (J6) are powered from the VUSB_5V0 only. This was intentional so that this interface could power cycle the board and remain powered. But those might need some additional mods to get out of the way of device reset. 
    • The 1.2V and 3.3V digital buck-converters will come on without any issue, as will the ethernet LDO. 

    Also: 

    • The J9, J10 and J13, J14 jumpers need to be installed to short VSYS_3V3 and VSYS_5V0 to the different BoosterPack power pins. This is setup so BoosterPack designers have the option of accepting/delivering power to/from the LaunchPad or not. 
    • J11 and J12 directly connect to the VSYS_3V3 and VSYS_5V0 - no jumpers

    I will try and look at this in the lab in a few days. Would probably be just a few resistor mods to make it work off the power jumpers vs. USB-C connector

    Abdul Razak said:
    in User guide J6.55 is SPI0 in Figure 4-24. AM263x LaunchPad BoosterPack Pinout and SPI1 in "Table 4-24. Pinmux Options for J6"

    Follow what is in the latest schematics in the SPRR433 SPRR452. I do need to make a correction to this in the User's Guide. Design intent was for all of the SPI0 interface to be available on J5/J8. However, some pins were placed on J1/J4 where the SPI1 channels are brought out. 

    Thank you,

    -Randy

  • 0 in reply to Randy Rosales
    Prodigy 135 points

    Hi Randy,

    Thanks for the response.

    the SPRR433 mentioned is for LP-AM243: https://www.ti.com/tool/LP-AM243#design-files 

    and SPRR452.ZIP is for LP-AM263 : https://www.ti.com/tool/LP-AM263#design-files 

    kindly confirm.

  • 0 in reply to Abdul Razak
    TI__Mastermind 18760 points

    Yes. You are correct - I have edited the previous reply to correct this. 

    -Randy

  • 0 in reply to Randy Rosales
    TI__Mastermind 18760 points

    Hi Abdul, 

    If you apply 5.0V on the J11 header, the TPS22965 (U19) power switch will power on the VUSB_5V0 and all of the downstream components. I just tried this in the lab and everything looks good (AM263x power, reset good, can connect and run code on the AM263x). 

    However, it looks like the power switch presents a larger resistive load in this back-fed mode, so the resulting VUSB_5V0 is pretty slow. This in turn makes the output of the VSYS_TA_3V3 low (2.4V or so). But this is enough for the pull resistors on the VSYS_TA_3V3 rail to get past the VIH.low of the POR reset signals they feed. 

    I am making additions for the next rev of this board. I'll add a way to power this from BoosterPack/J11 properly. 

    Thank you,

    -Randy