TA0319 - TECHNICAL ARTICLE
Figure 4.
Main features of the different losses
Power losses
3 Key parameters of damper diodes
P
on
= F(V
FP
, F)
P
cond
= F(V
F
, I
P
)
P
off
= F(F
C
)
P
rev
<<<<
F
C
= F(trr, V
CEsa
t, T
j
)
Frequency
3.3
DAMPER diodes design rules
For CRT TV applications, the deflection frequency in a 100Hz or HDTV CRT TV design is lower
than 56kHz. Therefore, a maximum t
rr
of 250ns is fully compatible with high end CRT TV
designs. For CRT Monitor application, where deflection frequencies can go up to 110kHz, the
t
rr
value becomes a critical parameter to minimize the power losses.
The qualification criteria for damper diodes, in addition to good screen image quality, is the
temperature of the case and the leads at the solder joins (consequence of power losses). This
temperature has to remain inside the design rules (lower than a defined value).
Also, a key qualification criteria is the total solution cost of the deflection circuit.
In addition, for big screen size, the deflection circuit is enriched with an east-west correction
circuit. This circuit needs 600V diodes. These diodes are either standalone (in axial or through
hole package) or integrated with the damper diode in a 3-pin full molded TO-220 package. The
choice between stand alone and integrated solution is based on the cost / performance trade-
off.
Figure 5.
Basic circuit of the horizontal deflection circuit with East-West correction
B+
HT
5/10
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