AN280

Snubber design considerations

Doc ID 1703 Rev 3

11/15

4.1

Current in the snubber circuit

Figure 12.

Turn-on 2.0 A/div

The power dissipated in the snubber resistor is the sum of the dissipation during the turn-on

and turn-off of the bridge. The resistor dissipation is:

Equation 5

where

●

I1 = current at turn-on

●

I2 = current at turn-off

●

R = snubber resistor

●

DC = duty cycle of current flow

For the design example the power dissipation, not considering the duty cycle is:

Equation 6

If the device is chopping for only a portion of the time the dissipation in the resistor is

reduced.

AM15179v1

Pd

I1

2

RDC

⋅⋅

()

I2

2

RDC

⋅⋅

()

+

=

Pd

2.5

()

2

7.5

0.01

·

⋅⋅

()

5

()

2

7.5

0.01

·

⋅⋅

() 0.469 1.875 2.344W

=

+

=

+

=