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Is it possible to switch an AC load using two MOSFETs in anti-series such as the picture below?

enter image description here

In this mode, each MOSFET is on during one half of the wave and the other's body diode conducts to complete the circuit.

enter image description here

Source

With some MOSFET's RDSON approaching 4mOhm, there is very little loss (heat generation) by the FET. However, the body diode or even external Schottkey diode can easily dissipate one watt/ampere given the near 1Volt drop.

Is there a more efficient a circuit that would use just the transistors and no diodes for the typical AC wave?

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    \$\begingroup\$ Why do you think the body diode is conducting during one half-cycle? If Vgs is high enough to turn the FET on, it turns BOTH FETs on as the gates and sources are tied together. The challenge is the floating drive to the gates, but there are optically coupled photovoltaic solutions if you don't need high speed switching. \$\endgroup\$ – John D Dec 12 '18 at 20:13
  • \$\begingroup\$ When one fet is on, so is the other. The diode only comes into play when the solid state relay is inactivated. \$\endgroup\$ – Andy aka Dec 12 '18 at 20:50
  • \$\begingroup\$ Are you trying to make a full wave rectifier with low voltage drop? \$\endgroup\$ – Harry Svensson Dec 13 '18 at 3:17
  • \$\begingroup\$ @JohnD I'm going off of page five of TI's app note. I updated the pictures. They suggest flow through the diode. Is that wrong? or am I missing something? \$\endgroup\$ – MandoMando Dec 14 '18 at 14:43
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    \$\begingroup\$ @MandoMando I'm sorry to say that the TI guy who drew that picture is wrong. Both MOSFETs are on and both shunt their respective body diodes no matter what direction current is flowing. \$\endgroup\$ – Andy aka Dec 14 '18 at 15:08
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In this mode, each MOSFET is on during one half of the wave and the other's body diode conducts to complete the circuit.

No that's not true precisely. Both MOSFETs turn-on when the correct gate-source voltage is applied and their respective channels will conduct in either direction of current. Thus, the body diodes are shunted by their respective DS channels: -

enter image description here

The above graph is from here and clearly shows that with reverse DS voltage and current (but still the same positive gate-source voltage) you get nearly identical conduction compared to the forward case.

Clearly, when VGS = 0 the body diode starts to conduct in reverse as seen by the light blue line.

So, I'm sorry to say that the TI person who drew and described that picture is wrong. Both MOSFETs are on and both shunt their respective body diodes no matter what direction current is flowing. I've submitted an error report to TI by the way.

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