TDA6120Q Datasheet, PDF (10/16 Pages) NXP Semiconductors – Video output amplifier

Philips Semiconductors
Video output amplifier
Preliminary specification
TDA6120Q
x
Vi
0
t
x
tst
162.5
150
Voc
100
50
37.5
overshoot (in %)
to(r)
tpd
38.75
36.25
t
MGK445
Fig.7 Output (pins 12 and 13; falling edge) as a function of input signal.
FLASHOVER PROTECTION
The TDA6120Q does NOT include protection diodes that
clamp the cathode output pin to the high voltage supply pin
during a CRT flashover discharge. Therefore an external
high voltage reverse biased diode has to be connected
between the OUTC pin and the V_DD pin. An external 147 Ω
carbon high-voltage resistor in combination with a 2 kV
spark gap between the cathode and ground will limit the
maximum clamp current (for this resistor value, the CRT
has to be connected to the main printed-circuit board).
This external network causes an increase in the rise and
fall times and a decrease in the overshoot.
Pin 10 must be decoupled to pin 8:
• By a capacitor >22 nF with good HF behaviour (e.g. foil).
This capacitor must be placed as close as possible to
pin 10 and pin 8; definitely within 5 mm.
• By a capacitor >3.3 µF on the picture tube base printed
circuit board (common for three output stages).
1997 Aug 27
10