cupoftea
Advanced Member level 6
Hi,
The attach shows the well known input circuit to an SMPS, (here vin = 24V and power is 50W.)
The SMPS controller must stay disabled until the PFET(s) switch has completely turned ON.
The PFET(s) must stay off until the 220R resistor has charged the input capacitor up to VIN.
The comparator should turn off the controller if VIN falls below 8V.
However, I suspect that the comparator (MIC7712) will, just after the VIN gets switched in,
turn on spuriously for a short interval and turn on the PFETs prematurely and give an unfortunate inrush
surge through the PFETs.
Would you agree?
The attach shows the well known input circuit to an SMPS, (here vin = 24V and power is 50W.)
The SMPS controller must stay disabled until the PFET(s) switch has completely turned ON.
The PFET(s) must stay off until the 220R resistor has charged the input capacitor up to VIN.
The comparator should turn off the controller if VIN falls below 8V.
However, I suspect that the comparator (MIC7712) will, just after the VIN gets switched in,
turn on spuriously for a short interval and turn on the PFETs prematurely and give an unfortunate inrush
surge through the PFETs.
Would you agree?
