Vertical deﬂection booster
6.2 Pin description
positive supply voltage 1
ﬂyback supply voltage
ﬂyback generator output
supply voltage 2 for vertical output
ground or negative supply voltage
inverted input of differential input stage
non-inverted input of differential input stage
7. Functional description
Both the TDA4865J and TDA4865AJ consist of a differential input stage, a vertical output
stage, a ﬂyback generator, a reference circuit and a thermal protection circuit.
The TDA4865J operates with a separate ﬂyback supply voltage (see Figure 1) while the
TDA4865AJ generates the ﬂyback voltage internally by doubling the supply voltage
(see Figure 2).
7.1 Differential input stage
The differential sawtooth input current signal (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.
7.2 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 of
Tj > 150 °C the protection will be activated and will reduce the deﬂection current (IVOUT).
7.3 Flyback generator
The ﬂyback generator supplies the vertical output stage during ﬂyback.
The TDA4865J is used with a separate ﬂyback supply voltage to achieve a short ﬂyback
time with minimized power dissipation.
The TDA4865AJ needs a capacitor (CF) connected between pins VP3 and VP2 (see
Figure 2). Capacitor CF is charged during scan, using the external diode D1 and resistor
R5. During ﬂyback the cathode of capacitor CF is connected to the positive supply voltage
and the ﬂyback voltage is then twice the supply voltage. For the TDA4865AJ the
resistor R6 in the positive supply line can be used to reduce the power consumption.
Product data sheet
Rev. 02 — 3 November 2006
© NXP B.V. 2006. All rights reserved.
4 of 18