Assuming identical voltage and current rating, which is having higher switching speed? MOSFET or Schottky diode?

In synchronous buck converter, we replace Schottky diode with MOSFET (low side) for reducing the conduction loss. I want to understand the impact on switching loss due to this.

I realise MOSFET gate-source terminals act like a capacitor which needs to be charged and discharged everytime switching occurs. Whereas Schottky diode is a majority carrier device which requires no recombination of minority carriers. So can I say Schottky diode would be faster? I'm not sure whether I'm comparing apples to oranges.

  • \$\begingroup\$ Depends. Have you compared the datasheets of two recent and popular MOSFET and Schottky diodes respectively? \$\endgroup\$ – winny Nov 12 '19 at 12:41
  • \$\begingroup\$ MOSFETs have a body diode that can be quite fast and some MOSFETs contain a schottky in addition to the regular high speed (ish) body diode so, which MOSFET and which schottky diode are you wanting to compare? \$\endgroup\$ – Andy aka Nov 12 '19 at 12:53
  • \$\begingroup\$ I'm not sure whether I'm comparing apples to oranges. In my opinion you are comparing apples to oranges. The switching speed of a MOSFET heavily depends on how fast you can (dis)charge the gate. Ideally you would need an ideal voltage source to do that, then the gate resistance would be the limiting factor. Also a diode switches on/off by reversing the voltage while a MOSFET is a controlled device. \$\endgroup\$ – Bimpelrekkie Nov 12 '19 at 13:06
  • \$\begingroup\$ @ Andy aka Let me clarify: Iam trying to compare the switching speed of MOSFET channel ( not body diode) with a standalone Schottky diode ( not in parallel with MOSFET). \$\endgroup\$ – Divya K.S Nov 14 '19 at 10:39
  • \$\begingroup\$ @Winny I could not find the rise time (switching speed) information in any of the schottky diode datasheet. Not sure why it is not specified.( eg: 1N5819, STPS2200). As per wikipedia it is up to tens of nanoseconds for special high-capacity power diodes. Whereas in many MOSFET datasheets the rise rime and fall time are specified for a certain value of gate resistance and varies from tens of nano second to higher. ( eg: sct2120af,NTGD3147F, IRF630S) \$\endgroup\$ – Divya K.S Nov 14 '19 at 10:47

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