Is it acceptable to use a body diode between the drain and source?

It is possible to actively use a body diode between drain and source. It is actually used in motor drive circuits, power supply circuits, etc.

The figure below shows the positions where body diodes are formed in MOSFET cross-section, and the equivalent circuitry considering parasitic elements.
For MOSFET used in these applications, we describe the specifications for body diodes in the datasheet.

Fig. 1: Example of absolute maximum ratings
Fig. 1: Example of absolute maximum ratings
Table 1: Items and Descriptions

Item

Symbol

Unit

Description

Drain reverse current (continuous)
Drain reverse current (pulse)

IDR

IDRP

A

The maximum forward current allowed for the body diode of the MOSFET.

Forward voltage (diode)

VDSF

V

Drain-source voltage when forward current is applied to the body diode.

Reverse recovery time

trr

ns

These are the time (trr) and charge (Qrr) until the reverse recovery current disappears in the reverse recovery operation of the body diode under the specified measuring conditions. The peak current at that time is Irr.

Amount of reverse recovery charge

Qrr

μC

Peak reverse recovery current

Irr

A

Diode dv/dt ruggedness

dv/dt

V/ns

Ruggedness the drain-to-source voltage fluctuation during diode reverse recovery.
Table 2: Examples of data sheets

Item

Symbol

Measurement conditions

Minimum

Standard

Maximum

Unit

Forward voltage (diode)

VDSF

IDR = 30.8 A, VGS = 0 V

-

-

-1.7

V

Reverse recovery time

trr

IDR = 15.4 A, VGS = 0 V-dIDR/dt = 100 A/μs

-

135

220

ns

Amount of reverse recovery charge

Qrr

-

0.6

-

μC

Peak reverse recovery current

Irr

-

10

-

A

Diode dv/dt tolerance

Dv/dt

IDR = 15.4 A, VGS = 0 V, VDD = 400 V

50

-

-

V/ns

The body diode is described in the application note "Electrical properties: Power MOSFET application note". Please refer to this as well.

Back to FAQs of MOSFETs / Bipolar Transistors / IGBTs

A new window will open