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PSoC 5, 3 & 1 MCU

New Contributor II

hello all ,

i have a custom pcb with psoc 5 on it ,

i have 5 diffrent  voltage inputs (3.3v , 2.5v, 2.4v  ,1.1v ,1v) that i want to constantly monitor ,

for this task i want to use the Voltage Fault Detector block ,

the problem is that on the 3.3v rail i cannot seems to generate powergood signal

it always stays 0 , my settings -  OV: 3.6V UV: 3.1V DAC range:4V ,

all others rails is generating powergood signals as expected,

i measured with scope and i know there is a stable 3.3V input ,

if i switch to Power Monitor block all rails is good ,

am i doing somting wrong ?

mybe the Voltage Fault Detector block just cant measure 3.3V ??

Thanks lampel

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1 Solution
Employee

Hi,

The Voltage Fault Detector uses the internal VDAC to define the OV and UV threshold. If you are powering PSoC at 3.3V the maximum voltage you can drive the internal VDAC is around 85% of VDDA.

That's why you can't monitor the 3.3V input directly (assuming you are powering PSoC at 3.3V). There are two ways to solve this:

- Increase the VDDA to 5V

- Use a circuit divider to drop 3.3V below of 85% of 3.3V

View solution in original post

3 Replies
Employee

Hi,

The Voltage Fault Detector uses the internal VDAC to define the OV and UV threshold. If you are powering PSoC at 3.3V the maximum voltage you can drive the internal VDAC is around 85% of VDDA.

That's why you can't monitor the 3.3V input directly (assuming you are powering PSoC at 3.3V). There are two ways to solve this:

- Increase the VDDA to 5V

- Use a circuit divider to drop 3.3V below of 85% of 3.3V

View solution in original post

New Contributor II

hello ,

thanks for the answer ,

if so why is the powerMonitor block is working fine ?

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Employee

The Power Monitor component does not use the VDAC. It uses the ADC to scan the voltages. Therefore, it will not present the problem you described.