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PSoC™ 4 Forum Discussions

ALDE_1053476
Level 3
Level 3
10 replies posted 10 questions asked 10 sign-ins

Hello,

I'm working to a Project that has an USB connection configured as Self Powered.

I'll use CY8CKIT-149 to make a first Prototype.

In order to implement Self powered configuration, R7 and D1 will be removed.

Kitprog will be fed throug J6, PSoc and BLE module will be fed through J1 / J2.

My question is:

What happens if I switch off supply to CY8CKIT-149 while USB Cable remains connected to host?

Should I expect damages to Kitprog  USB Interface?

Thanks,

Alfonso

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Ekta
Moderator
Moderator
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250 solutions authored 100 likes received 250 sign-ins

What about if I only remove D1, leaving PSoC5LP bus Powered?

Should I expect Any damage to PSoC 4 when it's not powered?


If you remove D1 PSoC 4 will not longer be powered from the VBUS (USB) but PSoC 5LP will be powered. Thus you would not be able to program PSoC 4 if you are not powering it externally through VTARG.


Should I expect any Damage to PSoC5LP when PSoC 4 is Powered and USB Cable is not connected?

There should not be any damages to the PSoC 5lp when PSoC 4 is powered and USB Cable is bot connected.

Note that in case you are removing bot R7 and D1 then you need to power PSoC 5LP and PSoC 4 externally using the VDDD and VTARG pins respectively.

Best Regards

Ekta

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ALDE_1053476
Level 3
Level 3
10 replies posted 10 questions asked 10 sign-ins

One more question:

What about if I only remove D1, leaving PSoC5LP bus Powered?

Should I expect Any damage to PSoC 4 when it's not powered?

Should I expect any Damage to PSoC5LP when PSoC 4 is Powered and USB Cable is not connected?

Thanks,

Alfonso

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Ekta
Moderator
Moderator
Moderator
250 solutions authored 100 likes received 250 sign-ins

What about if I only remove D1, leaving PSoC5LP bus Powered?

Should I expect Any damage to PSoC 4 when it's not powered?


If you remove D1 PSoC 4 will not longer be powered from the VBUS (USB) but PSoC 5LP will be powered. Thus you would not be able to program PSoC 4 if you are not powering it externally through VTARG.


Should I expect any Damage to PSoC5LP when PSoC 4 is Powered and USB Cable is not connected?

There should not be any damages to the PSoC 5lp when PSoC 4 is powered and USB Cable is bot connected.

Note that in case you are removing bot R7 and D1 then you need to power PSoC 5LP and PSoC 4 externally using the VDDD and VTARG pins respectively.

Best Regards

Ekta

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Hi Ekta, 

Thanks for Your Reply.

However I'm still concerned of one detail:

Let's suppose Power supply to Kit-prog to be OFF while USB voltage and/or Target Voltage are ON.

USB Voltage reaches P1.7 of Kit-Prog PSoC through R2-R36.

Target Voltage reaches P3.3 through R15-R50.

Both pins are standard GPIOs (not SIOs) thus withstanding max 100 uA Current flowing through them from a Source voltage higher than Supply Voltage.

This limit may be trespassed  when power to KIt-prog is off.

Do you agree?

Thanks,

Alfonso

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Ekta
Moderator
Moderator
Moderator
250 solutions authored 100 likes received 250 sign-ins

Hello Alfonso,

On removing the R7 resistor PSoC 5LP will no longer be powered through VBUS.

On removing D1 diode PSoC 4 will no longer be powered from VBUS.

    


What happens if I switch off supply to CY8CKIT-149 while USB Cable remains connected to host?

Should I expect damages to Kitprog  USB Interface?


Although the USB cable remains connected USB would not be able to power the PSoC 5LP . This should not cause any damage to the USB Interface.

Best Regards

Ekta

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