Switching Frequency
It is the value showing how many times per second the power stage turns on and off, expressed in hertz. In low-voltage DC motor drivers it is typically chosen between 1 kHz and 25 kHz. The choice determines the balance between audible hum and driver heating.
When you raise the frequency, three things improve: the current ripple in the motor winding decreases, the mechanical hum moves out of the audible band above 20 kHz, and current control becomes smoother. In return, because switching loss increases in direct proportion to frequency, the driver heats up more.
A low frequency (typically 1–4 kHz) does the opposite: the loss decreases, but a clear hum is heard from the motor and the current ripple grows. This means both a slight oscillation in torque and additional heating in the winding.
The practical recommended range is this: 16–20 kHz solves most hum complaints, and in MOSFET-based drivers 20–25 kHz is widely accepted as an optimum. The frequency is determined by the driver manufacturer at the design stage and may not be open to user adjustment. On AXI's DC driver modules the adjustment pots the user has access to are for speed and ramp; the switching frequency is not offered as a user-changeable parameter.
Context where this term is used: DC Motor Driver Selection Guide