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Question about VDDD, USB, and Programming | Cypress Semiconductor

Question about VDDD, USB, and Programming

Summary: 1 Reply, Latest post by bobgoar on 10 Sep 2015 01:31 PM PDT
Verified Answers: 1
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R04's picture
16 posts



I'm working on a layout that is using a PSOC5LP. I'd like to run the PSOC5LP off 3.3V but still provide a USB interface with computers. With VDDD hooked to 3.3V, I'll have to set the USBUART block to run in 3.3 mode, is there anything I have to hook up externally to the USB pins to make it work with a computer? If VDDD is set to 3.3V and I use a 5V computer USB input, am I destined to destroy the PSOC?



Thanks for the help in advanced,


user_242978793's picture
961 posts

Ro4: You have to remove diode D1 from the board if you plan to run the board on 3.3 Volts and you have to remove the On Board  Programming section of the 5LP. And program it with that before you connect your external Power source. 

In order to use an external power supply, while KitProg is connected to the PCB USB, remove
diode, D1, from the board. This ensures that VTARG supply from KitProg is not supplied to the target
device. KitProg measures the target voltage and adjusts the logic levels on the programming pins
It is important to understand that this prototyping kit does not have any onboard ESD protection
circuitry. Therefore, the power source for the PSoC 5LP Prototyping Kit must be of a high quality to
ensure that the board is protected from any over-current conditions and swapped-power

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