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RCAT-1A Rev A3 Designer’s manual
Serious Power for the Serious Designer
Alternatives for controlling the mosfets
Notice the schematic below that the CPU port PL0 directly controls Q3:
Figure 21
Now notice in the diagram below that PL0 also connects to jumper JP28 which then goes to J5. This opens the
option of controlling the mosfet from the CPU or from an external source. Of course if you decide to utilize
external control you will need to install a shunt on JP28. You should also make sure that port PL0 on the CPU is
configured as a high-impedance input to avoid back-driving the external input and possibly damage one or both
ends of the circuit.
One possible configuration of this arrangement might provide for PWM control of the mosfet by connecting one
of the PWM outputs (for example J5 position 2 which is the PE3/OC3A PWM output from the CPU) to the PL0_A
input of J5.
Figure 22
Install shunt
