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MSP432P401R: Custom Dev Board Schematic Questions

Wes Piard
Prodigy 140 points
Part Number: MSP432P401R
Other Parts Discussed in Thread: MSP-FET

Hello, 

I'm making a custom development board for the MSP432P401R. I am using the MSP432 launchpad schematics as a reference when designing this. I have included my schematic below. I'm not using the low or high frequency external oscillators, so I'm just leaving the relevant pins disconnected. I just have a few questions before I start designing my PCB. 

Are all of the DVCC pins "weighted" equally? Sorry if there is better terminology. What I mean is does it matter which pin I put my 10uF electrolytic capacitor (C3) next to? Or should I put it close to my "Power" header? 

Currently, I don't have a 4.7uF capacitor (C4) on hand, but may be able to get one. If I'm not able to get one, can I use a larger electrolytic capacitor instead?

Also, is a 10-ohm resistor (R1) fine to connect VCC (3.3V) to AVCC? And does the 0.1uF (C15) cap create a low-pass filter to eliminate high-frequency noise from the analog reference?

And FYI, I'm using an MSP-FET programmer. That's why my programmer connector (P13) is setup the way it is. 

  • 0
    Guru 74080 points

    Hi Wes!

    Wes Piard said:
    What I mean is does it matter which pin I put my 10uF electrolytic capacitor (C3) next to? Or should I put it close to my "Power" header? 

    It is recommended to place a combination of 4u7 and 100n to each power pair of the MSP432. You can also read about this in the datasheet (page 180).

    Wes Piard said:
    Currently, I don't have a 4.7uF capacitor (C4) on hand, but may be able to get one. If I'm not able to get one, can I use a larger electrolytic capacitor instead?

    Larger values can be used, but they will increase ramp-up time. The capacitor on DVcc should not be smaller than the one on Vcore.

    Wes Piard said:
    Also, is a 10-ohm resistor (R1) fine to connect VCC (3.3V) to AVCC? And does the 0.1uF (C15) cap create a low-pass filter to eliminate high-frequency noise from the analog reference?

    A resistor followed by a capacitor always forms a low-pass-filter. If you do not plan to use analog parts (ADC for example) of the MSP432 you can connect both rails directly. Otherwise you may also think about decoupling capacitors at the reference pins. This depends on your future usage of the board.

    Dennis

  • 0 in reply to Dennis Eichmann
    Prodigy 140 points

    Hey!

    Dennis Eichmann said:
    Larger values can be used, but they will increase ramp-up time. The capacitor on DVcc should not be smaller than the one on Vcore.

    I have plenty of 4.7uF electrolytic caps, as far as I know the main difference is the ESR, correct? Does this matter for DVCC caps?

    Dennis Eichmann said:
    Otherwise you may also think about decoupling capacitors at the reference pins. This depends on your future usage of the board.

    I will be using the ADC for some basic audio sampling, but I won't be using any external references. Right now I have a 10-ohm resistor connecting DVCC to AVCC and two 0.1uF caps going from AVCC to GND. 

    Thank you!

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