MK24FN1M0VDC12 does not run from the fast clocks, VOUT33 dips

[j_sikken]

I have a problem that the MK24FN1M0VDC12 MCU does not start from the "fast" clocks. It can be programmed fine. It runs fine in debug mode stepping through the code. The VOUT33 which is 3.3V has dips down to 1.7V with 5ms interval and the MCU resets. I power the MK24FN1M0VDC12 with 5V on the VREGIN pin and the 3.3V LDO output on pin VOUT33 is connected to the VDD pins of the MCU. There is an 2.2uF ceramic capacitor on the output. According to datasheet/manual the LDO has two different maximum output currents. 120mA in RUN mode and 1mA in STANDBY mode.

Do you think my LDO was in STANDBY mode?

How do I change it to RUN mode?

Please note I have not programmed this MCU myself. When I was away my colleague tried to run the embedded code.

[jingpan]

Hi Jasper,

Internal power mode signals control whether the module is in RUN or STANDBY mode. So, it is not control by software. Can you share your hardware diagram?

There is USB hardware design guide in below document. You can take a reference.

https://community.nxp.com/servlet/JiveServlet/download/472565-1-286410/KQRUG.pdf

Regards,

Jing