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Strange voltage on RST pin msp430g2553 TSSOP 20 pin

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Did you measure VCC on the problematic boards? Did you try powering from a 5V power supply?

 

220uF is to much capacitance on VBUS and total overkill for this kind of application. I think the USB spec only allows for 10uF or so. Inrush current may lead to the USB power supply to be shut off and on and off etc.

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Did you measure VCC on the problematic boards? Did you try powering from a 5V power supply?

 

220uF is to much capacitance on VBUS and total overkill for this kind of application. I think the USB spec only allows for 10uF or so. Inrush current may lead to the USB power supply to be shut off and on and off etc.

I also try to connect to VCC/GND pins on G2 Launchpad (without LDO and 220uF). Voltage still dropped.

Both of voltage on P2.2 button and VCC pin (my PCB) is fine, around 3.3 Volt. Only RST pin has problem.

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Did you measure VCC on the problematic boards? Did you try powering from a 5V power supply?

 

220uF is to much capacitance on VBUS and total overkill for this kind of application. I think the USB spec only allows for 10uF or so. Inrush current may lead to the USB power supply to be shut off and on and off etc.

Could you please help to explain about high capacitance on VBUS will cause problem? I just think it will make more stable.

Which kind of 10uF (footprint 0805, 1206, ...) I should use in this situation ?

Thanks!

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A large capacitor needs to be charged on initial power-up. This will cause a current spike for a few milliseconds on startup. USB outputs on PCs are protected from overcurrent to avoid damaging the PC in case of a short. This means that the PC may shut off USB power if it sees to much current.

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Take a look at the output cap(s) on the regulator as well, I assume the regulator is TLV70033 not TLV33.

TI recommend a 1uF low ESR ceramic cap (> 0.1uF should be ok according to the datasheet), IMO close to the terminals, for stability.

Why the 220uF? - it may cause problems for the regulator...

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Dear

 

Take a look at the output cap(s) on the regulator as well, I assume the regulator is TLV70033 not TLV33.

TI recommend a 1uF low ESR ceramic cap (> 0.1uF should be ok according to the datasheet), IMO close to the terminals, for stability.

Why the 220uF? - it may cause problems for the regulator...

May be that is my problem, could you suggest a specific part of 1uF, should I use a electrolytic capacitor or 0805, 1206, ... surface mount?

Anyone who has experience with this problem, please help

Thanks!

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Dear everyone,

I solved my problem, it came from the way I solder the MCU.

Thank for all support! By this thread, I was learned many thing.

Much appreciated!

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