PWM npn sinking signal
Page 208 shows the block diagram of a typical I/O port.



The PWM peripheral communicates with the output drivers via the output multiplexers. Therefore the sink/source capabilities in PWM mode are the same as when they're in GPIO mode, which for this device is either 15mA or 20mA.

You may need to use an external driver fed from the PWM signal if you need strong sinking and sourcing capabilities.