8 years, 1 month ago.  This question has been closed. Reason: Off Topic

FRDM-K64F: Wrong power output

Hi,

I have an eval board FRDM-K64F connected to a Lenovo laptop through USB (nothing else connected on the eval baord) and when I measure voltage I read value that are 1.5V to 2V higher than expected. The VBUS-5V pin is around 7V whereas the one labelled 3.3V are around 4.8V. Even when I'm trying to control the DAC0_OUT pin, I need to compute the value as if the maximum output was 5V instead of 3.3V:

Want 1.8V but for some reason all voltages are 2V too high on the eval board gAnalogOut.write_u16((1.8 * 0xFFFF) / 4.9);

Using this formula, I obtain close to 1.8V on DAC0_OUT.

It this normal?

We need two 5V sources and if we use the 3.3V ones (since we recorded something close to 5V) there seems to not have enough current.

My goal is to power to 5V two external boards and provide 1.8V as a ref to one of the two. Can I achieve this using the FRDM-K64F board?

Thanks,

Sylvain