Why is the internal clock of the MCP39F5xx not working?

There is no configuration to turn the built-in oscillator (OSC) off. The use of external traces on the OSC pin can make the pin ring, causing the device to consider the noise as coming from an external OSC. If you are going to use the internal OSC, there should be NO traces connected to the OSC pins. Please refer to the "MCP39F511 Power Monitor Demonstration Board User's Guide".

Note that on the layout side, there are no trace pads connected to the OSC pins.

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