Philips Semiconductors
Product specification
Vertical deflection booster
FUNCTIONAL DESCRIPTION
Both the TDA4863J and TDA4863AJ consist of a
differential input stage, a vertical output stage, a flyback
generator, a reference circuit and a thermal protection
circuit.
The TDA4863J operates with a separate flyback supply
voltage (see Fig.1) while the TDA4863AJ generates the
flyback voltage internally by doubling the supply voltage
(see Fig.2).
Differential input stage
The differential sawtooth input signal (e.g. coming from the
deflection controller family TDA485X) is connected to the
inputs (inverted signal to pin 6 and non-inverted signal to
pin 7). The vertical feedback signal is superimposed on
the inverted signal on pin 6.
Vertical output and thermal protection
The vertical output stage is a quasi-complementary
class-B amplifier with a high linearity.
The output stage is protected against thermal overshoots.
For a junction temperature T
j
> 150
°C
this protection will
be activated and will reduce then the deflection current (I
5
).
TDA4863J; TDA4863AJ
Flyback generator
The flyback generator supplies the vertical output stage
during flyback.
The TDA4863J is used with separate flyback supply
voltage to achieve a short flyback time with minimized
power dissipation.
The TDA4863AJ needs a capacitor C
F
between
pins 2 and 3 (see Fig.2). Capacitor C
F
is charged during
scan, using the external diode D1 and resistor R5. During
flyback the cathode of capacitor C
F
is connected to the
positive supply voltage and the flyback voltage is then
twice the supply voltage. For the TDA4863AJ the
resistor R6 in the positive supply line can be used to
reduce the power consumption.
In parallel with the deflection coil a damping resistor R
P
and an RC combination (R
S1
= 5.6
Ω
and C
S1
= 100 nF)
are needed. Furthermore, another additional
RC combination (R
S2
= 5.6
Ω
and C
S2
= 47 to 150 nF)
can be used to minimize the noise effect and the flyback
time (see Figs 9 and 10).
2000 Aug 17
6
ETC [ ETC ]
