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Hello everybody,
this is my first interaction in the community. I'm looking forward to be a part of this community.
So, this is my Question:
At the moment I work on a Cypress Controller Board (Like mbed) to control other Applications with CY8C5868AXI-LP035. And I have a question about the power supply from my 5LP Development Board. In this board they route from the USB port to the VIN and VOUT of the LDO. What is the reason? Could I not simply route from USB to VOUT pin to supply the design?
Sorry for my bad english!
Best regards,
Florian
Solved! Go to Solution.
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PSoC 5LP
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It is simply for voltage regulation.
Do you know, voltage of USB Vbus is not always 5.0v
When relay via USB Hub, the voltage down to 4.0v occasionally.
So, LDO will regulate these voltage to stable.
OK?
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Are you working with your own board or with a cypress kit if so which kit is it?
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A "typical" LDO needs anywhere from sub 100 mV to 300 mV to keep
its output at the regulation point. However the AP1117, which supplies
Vbus, has a droput > 1V, consult spec sheet. Looks more like a non-
LDO to me.
This is a linear lDO, so when regulator is in droput, the output drops
linearly with input V. So if dropout is 1.3V, and input to LDO is at 5.0
V, then its output, essentially saturated, is at 3.7 V.
Compounding this is a schottky is used on LDO in to insure no reverse
current flows back into LDO input, otherwise LDO could be damaged
and or USB physical interface. This diode further aggravates dropout
voltage.
Regards, Dana.
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The 10 pin header, from the board manual -
4.2.2 Programming Interface
This kit allows programming in two modes:
■ Using the on-board programming interface
Using the JTAG/SWD programming interface with a MiniProg3
and
4.2.2.2 JTAG/SWD Programming
Apart from the on-board programming interface, the board also provides the option of using the
MiniProg3. This interface is much faster than the on-board program interface. The JTAG/SWD
programming is done through the 10-pin connector, J3.
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Okay, thank you Dana!
And everybody else for your support.
Nice feature.
Best regards,
Flo