cupoftea
Advanced Member level 6
Hi,
Why do we see schems of eg synchronous SMPS with no diode turn-off for the synch fets?
Its well known that we often need to increase the gate series resistor so that turn on is slowed up.
However, we never want a synch rect fet to turn off slowly...because it lingering on may cause shoot-through currents.
So thus a synch rect fet needs a turn off diode, which bypasses any series high value gate turn on resistor.
But why do all the demo boards not feature this?
Why do we see schems of eg synchronous SMPS with no diode turn-off for the synch fets?
Its well known that we often need to increase the gate series resistor so that turn on is slowed up.
However, we never want a synch rect fet to turn off slowly...because it lingering on may cause shoot-through currents.
So thus a synch rect fet needs a turn off diode, which bypasses any series high value gate turn on resistor.
But why do all the demo boards not feature this?