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LAUNCHXL-F28P65X: hardware design questions

Lawrence Wang
Prodigy 600 points
Part Number: LAUNCHXL-F28P65X
Other Parts Discussed in Thread: TMS320F28P659DK-Q1

Tool/software:

Hi team

 

My customer is using F28P65X for single stage OBC project. Pls help with the below questions they have during designing the main controller circuit of TMS320F28P659DK-Q1 (176Pins) based on TI’s development board “LAUNCHXL-F28P65X”

1. For the pin path from XTAL to DSP, there is a 50ohm impendence matching marked on schematics, but no 50ohm resistor is connected in series. So how to achieve the impendence matching?

                

2. Regarding the MCU ADC ports, why the input capacitors are commented out? In the customer’s understanding, the input capacitors are used to provide filter function and provide transient current in high frequency sampling conditions, even need resistor in series to eliminate the oscillation.

3. Due to the special design in our project, customer put the MCU GND reference on HVDC- (high voltage DC output minus). Is it necessary to put an isolator between MCU side and JTAG input side? If yes, they need to generate additional 3.3V based on LV_GND for JTAG side and they also heard from their software engineer that the CCS may not be able to connect with their board with isolator (happens in the previous project). Could you please provide professional suggestions?

  • 0
    TI__Mastermind 45236 points

    Hi,

    1. This is highly dependent on your PCB design and manufacturing. If PCB design / manufacturer can guarantee 50 Ohm impedance matching for the clock signals these resistors really shouldn't be necessary, or the specific value needed may be different (not 10 ohm).
    2. Many of the inverter boosterpacks TI offers have RC caps on analog sensing signals already. The pads are included so the user can add RC filter as needed.
    3. I suggest looking at this eval board for isolated JTAG instead. Include a connector to directly connect to this board. https://www.ti.com/tool/XDS110ISO-EVM

    Best,

    Kevin