Meassoring the voltage across the FreeSoC2 Development Board - PSoC5LP

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Anonymous
Not applicable

hello I am currently using PSoc5 LP-096 in my project and i have 2 questions

1)On the  board I wanted to messure the voltage between the 5V and GND(ground) how ever when i messured it the voltage was 4.06V and not 5V why is that ?

2) I am using ADC block and my question is what is default Vref ? the reason i am asking is that if the Vref is 5 and in real messirment it gives me 4.06V it gives me wrong answer of the Output of the ADC 

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1 Solution

You power the board from USB - which probably is already less than 5V. From the Vusb pin to the 5V header pin, there is a reverse protection diode (about 0.3V loss) and LDO regulator (another 0.3-0.4V loss). These losses depend on the current the board is drawing. But do the math and you see that can expect, in the best case, 4.4V at this pin.

The 5V pin is actually a power _input_.

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5 Replies
HeLi_263931
Level 8
Level 8
100 solutions authored 50 solutions authored 25 solutions authored

1) where are you measuring the 5V? When you power by USB and select 5V, then the voltage regulator U2 (a MIC5219) is in the loop, together with D1. They account for at least 0.5V drop, probably more with some load. Look at the FreeSOC2 schematic for reference.

2) you can configure the reference in the ADC settings - you can use the internal reference or Vdda.

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Anonymous
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this is how i how i connected the voltage meter to the board :

Voltage_meter.png

and this the actually voltage i see :

20180424_162151.jpg

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Given the schematic, this voltage is to be expected at these connections.

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Anonymous
Not applicable

what do you mean ? all i did is measure the voltage between 2 pins

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You power the board from USB - which probably is already less than 5V. From the Vusb pin to the 5V header pin, there is a reverse protection diode (about 0.3V loss) and LDO regulator (another 0.3-0.4V loss). These losses depend on the current the board is drawing. But do the math and you see that can expect, in the best case, 4.4V at this pin.

The 5V pin is actually a power _input_.

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