3 Key parameters of damper diodes
TA0319 - TECHNICAL ARTICLE
Current, voltage and switching energy in DAMPER diode at turn on
For high switching frequencies, P
is high and V
becomes a critical parameter. V
increases with (dI/dt)ON. In this application, this parameter is mainly fixed and is generally
lower than 100A/µs.
Leakage current and reverse losses
The new family of DAMPER diodes uses new technology allowing a very low leakage current
and negligible reverse losses in comparison with the other losses.
Reverse recovery time (t
) and turn off switching losses (P
At t=t0, when the diode turns off, the reapplied voltage is low (V
of the transistor), and the
corresponding switching energy W
is also very low (between t0 and t1). Due to this low
reapplied voltage, the DAMPER diode takes time to evacuate all these reverse recovery
For a given frequency, if t
is too high, there are still charges when the transistor turns off (at
t1). In this situation the reverse recovery charge is evacuated over a high voltage inducing high
switching energy W
We can consider this as a critical frequency F
. Below F
is negligible (the DAMPER
diode has evacuated all the reverse recovery charges at t0).
, the switching energy increases very rapidly and can lead to a thermal runaway
problem. This critical frequency depends not only on the reverse recovery time, but also on the
operating junction temperature of the diode and V
of the transistor.
This is the reason why STMicroelectronics has developed two DAMPER diode families with t
optimized for the CRT TV deflection frequencies and optimized for CRT monitor frequencies.
summarizes the main features of the different losses as follows:
are proportional to V
depend on V
are negligible for F<F
and increase very quickly for F>F
depends on t