n Power Amplifier
n Flyback Generator
n Output Current up to 2 App
n Thermal Protection
n Stand-by Control
Description The STV9302A is a vertical deflection booster designed for TV and monitor applications.
This device, supplied with up to 35 V, provides up to 2 App output current to drive the vertical deflection yoke.
The internal flyback generator delivers flyback voltages up to 70 V. in double-supply applications, a stand-by state will be reached by stopping the (+) supply alone.
1. Usually the flyback voltage is slightly more than 2 x VS. This must be taken into consideration when
2. Versus pin 4
3. V3 is higher than VS during the first half of the flyback pulse.
4. Such repetitive output peak currents are usually observed just before and after the flyback pulse.
5. This non-repetitive output peak current can be observed, for example, during the Switch-On/Switch- Off phases. This peak current is acceptable providing the SOA is respected ( Figure 8 and Figure 9).
6. All pins have a reverse diode towards pin 4, these diodes should never be forward-biased.
7. Input voltages must not exceed the lower value of either VS + 2 or 40 volts.
When DC coupled (see Figure 4), the display vertical position can be adjusted with input bias. On the other hand, 2 supply sources (VS and -VEE) are required.
A Stand-by state will be reached by switching OFF the positive supply alone. In this state, where both inputs are the same voltage as pin 2 or higher, the output will sink negligible current from the deviation coil.
When both ramp signal and bias are provided by the same driver IC, you can gain natural rejection of any ripple caused by a voltage drop in the ground (see Figure 5), if you manage to apply the same fraction of ripple voltage to both booster inputs. For that purpose, arrange an intermediate point in the bias resistor bridge, such that (R8 / R7) = (R3 / R2), and connect the bias filtering capacitor between the intermediate point and the local driver ground. Of course, R7 should be connected to the booster reference point, which is the ground side of R1.
When idle, both driver outputs provide icm and the yoke current should be null (R1 is negligible),
4.3.2 Peak Current
Scanning current should be IP when positive and negative driver outputs provide respectively
icm - ip and icm + ip, therefore
and since R7 = R2:
Choose R1 in the 1W range, the value of R2 = R7 follows. Remember that i is one-quarter of driver
peak-peak differential signal! Also check that the voltages on the driver outputs remain inside
l Example: for icm = 0.4mA, i = 0.2mA (corresponding to 0.8mA of peak-peak differential
current), Ip = 1A
Choose R1 = 0.75W, it follows R2 = R7 = 1.875kW.
STV 9302A Comnparison is LA78040, STV9302B, AN5522, STV9378.