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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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ispn:40045:1:0
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l1:314:1:0
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PSoC4MCU
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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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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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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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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