Hey guys just wandering if theres a way to implement a soft shut down feature on outputs similar to the soft start to reduce back EMF on output shut down
Eg a high output radiator fan with a 2 second soft start when ramping up and a 2 second ramp down when the fan conditions are no longer met.
The main question is why?
Are you trying to solve some real-life issue with this?
I don’t see how back EMF can cause any negative effects.
Please explain why you think you need a feature like that.
Its getting late here and i noticed i used the wrong term im not worried about emf more so the voltage kick back of shutting off devices
Not trying to solve a specific issue but thought that having the ability to slow the speed of a motor down before completely shutting its power off would greatly reduce the voltage kickback which can only be a good thing for the pmu and the device being powered.
There are zero negative effects from the situation you are describing.
Let me explain.
If we want to slow down the motor, we have to use PWM.
Using PWM means switching the output off for a moment.
During that PWM-off moment, you get an identical voltage spike as you would during a normal switch-off.
If we go even deeper, we can look at the design of the DC motor.
A brushed DC motor has multiple windings mechanically switched by the commutator. So even with constant power supplied to the motor, the current is constantly switched between different windings. Which creates voltage spikes and even sparks you can sometimes see inside the motor.
That’s why you never hear about the “soft stop” feature. It has no electrical benefit. A slow stop might have mechanical benefits, but that would be a consideration only for complex mechanical systems.