TDA4864J Datasheet, PDF (6/16 Pages) NXP Semiconductors – Vertical deflection booster

Philips Semiconductors
Vertical deflection booster
Product specification
TDA4864J; TDA4864AJ
FUNCTIONAL DESCRIPTION
Both the TDA4864J and TDA4864AJ consist of a
differential input stage, a vertical output stage, a flyback
generator, a reference circuit and a thermal protection
circuit.
The TDA4864J operates with a separate flyback supply
voltage (see Fig.1) while the TDA4864AJ generates the
flyback voltage internally by doubling the supply voltage
(see Fig.2).
Differential input stage
The differential sawtooth input current signal (coming from
the deflection controller) is connected to the inputs
(inverted signal to pin INN and non-inverted signal to
pin INP). The vertical feedback signal is superimposed on
the inverted signal on pin INN.
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_V-OUT).
Flyback generator
The flyback generator supplies the vertical output stage
during flyback.
The TDA4864J is used with separate flyback supply
voltage to achieve a short flyback time with minimized
power dissipation.
The TDA4864AJ needs a capacitor C_F between
pins V_P3 and V_P2 (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 TDA4864AJ 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).
2003 Oct 31
6