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I'm using IRF3710 MOSFET H-bridge for 40A 12V motor driver. Should I use a schottky diode inside or should I use a separate one?

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  • \$\begingroup\$ What does the datasheet say? Your question is if you need one is unanswerable without much more information, including schematic. \$\endgroup\$ – winny Jan 20 at 9:05
  • \$\begingroup\$ The body diode that is inherent to most MOSFETs is NOT Schottky. Rather: it is an ordinary silicon diode. \$\endgroup\$ – Dwayne Reid Jan 22 at 2:54
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The IRF3710 has a body diode inside. See: IRF3710 - Datasheet

H-Bridge:

Diodes parallel to the MOSFET's (see schematic below) will ensure that the peak transistor voltage is limited to the input DC voltage and will also provide a conduction path for the magnetizing load current. (See: R. W. Erickson and D. Maksimović, Fundamentals of power electronics. New York: Kluwer Academic, 2004.)

schematic

simulate this circuit – Schematic created using CircuitLab

Body-Diode

The connection of bulk an drain in a MOSFET results in a body diode. Thus, a MOSFET always has such a diode. (Information about the Body Diode on Wikipedia)

Body diodes can be used in applications. However, usually they have a high reverse recovery time. If needed the body diode can be blocked with two diodes.

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  • \$\begingroup\$ They all do.... \$\endgroup\$ – Blair Fonville Jan 20 at 9:17
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    \$\begingroup\$ Yes =). I added some information. \$\endgroup\$ – Johannes Jan 20 at 10:06
  • \$\begingroup\$ Where you write "Full-Bridge", I think you mean H-Bridge or "Full-H" (maybe nitpicky). Also, they are usually constructed of 2 NFETs and 2 PFETs (you have drawn 4 NFETS). And the diodes need to be connected at the centers, otherwise what's the point of have two on each side? \$\endgroup\$ – Blair Fonville Jan 20 at 10:18
  • \$\begingroup\$ Oh, you fixed the diodes... \$\endgroup\$ – Blair Fonville Jan 20 at 10:19
  • \$\begingroup\$ You are right, I will change it to H-Bridge. \$\endgroup\$ – Johannes Jan 20 at 10:20

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