cupoftea
Advanced Member level 5
Hi,
Our customer sent us a 43W Offline SMPS with half wave rectification.
It needed to be half wave as the Neutral was required to be the ground of the output.
Anyway, do you agree, that half wave rectification is very bad, because it provides no
protection whatsoever against negative going transients on the mains?
A full wave bridge will quench both positive and negative mains transients, by quenching them
into the post rectifier filter capacitor....but a half wave rectified SMPS has no defence
whatsoever against a negative going mains transient. Its diode will pop with a
half decent transient.
As such, a half wave rectified SMPS needs the shown circuit to be included, shown ringed in the
attached.
Would you agree this circuit is needed?.....(the cap is made only 10uF, for cost reasons....not great,
but a lot better than nothing.)
(LTspice and .PNG attached)
Our customer sent us a 43W Offline SMPS with half wave rectification.
It needed to be half wave as the Neutral was required to be the ground of the output.
Anyway, do you agree, that half wave rectification is very bad, because it provides no
protection whatsoever against negative going transients on the mains?
A full wave bridge will quench both positive and negative mains transients, by quenching them
into the post rectifier filter capacitor....but a half wave rectified SMPS has no defence
whatsoever against a negative going mains transient. Its diode will pop with a
half decent transient.
As such, a half wave rectified SMPS needs the shown circuit to be included, shown ringed in the
attached.
Would you agree this circuit is needed?.....(the cap is made only 10uF, for cost reasons....not great,
but a lot better than nothing.)
(LTspice and .PNG attached)