Servo supply issue

Back to Robobot_B

The 5V supply and X9MG

The 5V servo supply may suddenly turn off. The issue is that when the servo stops, the extra energy is returned to the supply. The power supply enters shutdown mode when current flows in the reverse direction and can only be reset by a power cycle.

It looks like this:

The Orange and blue are the servo power (5V), and the green is the control pulse to the servo.

• The servo runs for about 130ms, then stops.
• When it stops, the supply reaches above 6V.
• After this, the 5V supply shut down.

5V protection 33uF

A series diode followed by a capacitor, in the 5V supply line.

With 33uF capacitor (Diode is 1A3 from DC components)

This looks good, but the overvoltage is high (>2V)

5V protection 100uF

A series diode followed by a capacitor, in the 5V supply line.

With 130uF capacitor (Diode is 1A3 from DC components)

This looks good, but the overvoltage is now ~1V, and that should be OK.