A jumper from pin 1 to pin 2 sets MODE high, forcing the converter into the
constant-frequency, heavy-load mode.
A jumper from pin 2 to pin 3 sets MODE low, forcing the converter into the
pulsed-variable low power mode.
Letting MODE float, not using a jumper on CB1, allows the converter to operate
in auto-mode, the output load detector circuitry determines if the converter
should be running inthe constant-frequency or pulsed-variable frequency
mode.