Pin Functions

STV9380A

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1

Pin Functions

Note 1. The voltage reference, accessible on pin 8, is for internal use only. No additional components

should be connected to this pin except the decoupling capacitor.

2

Functional Description

The STV9380A is a vertical deflection circuit operating in Class D. Class D is a modulation method

where the output transistors work in switching mode at high frequency. The output signal is restored

by filtering the output square wave with an external LC filter. The major interest of this IC is the

comparatively low power dissipation in regards to traditional amplifiers operating in class AB,

eliminating the need of an heatsink.

Except for the output stage which uses Class D modulation, the circuit operation is similar to the

one of a traditional linear vertical amplifier.

A (sawtooth) reference signal has to be applied to the circuit which can accept a differential or

single ended signal. This sawtooth is amplified and applied as a current to the deflection yoke. This

current is measured by means of a low value resistor. The resulting voltage is used as a feedback

signal to guarantee the conformity of the yoke current with the reference input signal.

The overvoltage necessary for a fast retrace is obtained with a chemical capacitor charged at the

power supply voltage of the circuit. At the flyback moment, this capacitor is connected in series with

the output stage power supply. This method, used for several years with the linear vertical boosters

and called “internal flyback” or “flyback generator”, avoids the need of an additional power supply,

while reducing the flyback duration.

The circuit uses a BCD process that combines Bipolar, CMOS and DMOS devices. The output

Table 1: STV9380A Pin Descriptions

Pin

Name

Function

Pin

Name

Function

Negative Supply

11

SGND

Signal Ground

Negative Supply

12

IN-

Error Amplifier Inverting Input

Negative Supply

13

IN+

Error Amplifier Non-inverting Input

4

OUT

PWM Output

14

EA out

Error Amplifier Output

5

CFLY+

Flyback Capacitor

15

Positive Supply

6

CFLY-

Flyback Capacitor

16

Positive Power Supply

7

BOOT

Bootstrap Capacitor

17

-VccPOW

Negative Power Supply

8

VREG

Internal Voltage Regulator

18

Negative Supply

9

FEEDCAP

Feed-back Integrating Capacitor

19

Negative Supply

10

FREQ

Frequency Setting Resistor

20

Negative Supply