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AN443 APPLICATION NOTE

Example

– Given:

– Use of a 3-BYT12PI-1000 for VM = 2500V

– Operating conditions:

– Tj = 100°C

– di/dt = 20A/ms

– F = 25 kHz

–

δ = .5

– Rectifier specification:

Problem

3 TRANSIL diodes are connected in series across each rectifier. What is the suitable part number?

Design Steps

– Power dissipation in steady state:

with

P1 < 330mW

– Power dissipation in switching phase:

with

F = 25 kHz and n = 3

then P2 < 1.2W

– Max total power dissipation P1 + P2 1.530 W

Solution: 1.5 KE series can be used (1.5KE300CP)

CONCLUSION

When using several fast rectifiers in series it is necessary to make sure that no diode will be subjected to

continuous or transient voltages in excess of their ratings.

In most cases, this is achieved by using sharing networks across each diode. It is important to optimize

this circuit in order to reduce power consumption and to save space.

Parallel resistors can be optimized by using the model of the fast recovery diodes reverse characteristic

proposed in this paper. Then, thanks to a good knowledge of the reverse current and its variation in the

V

2500

3x3

-------------

277V

=

>

V

1000

3

-------------

333V

=

>