TDA4867 데이터 시트보기 (PDF) - Philips Electronics

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TDA4867

Full bridge current driven vertical deflection booster

Philips Electronics 

Philips Semiconductors

Full bridge current driven vertical

deflection booster

Preliminary specification

TDA4867J

PINNING

SYMBOL

INP

INN

VP

OUTB

GND

OUTA

VFB

GUARD

FEEDB

PIN

DESCRIPTION

1 non-inverted input

2 inverted input

3 supply voltage

4 output B

5 ground

6 output A

7 flyback supply voltage

8 guard output or power save

mode input

9 feedback input

handbook, halfpage

INP 1

INN 2

VP 3

OUTB 4

GND 5 TDA4867J

OUTA 6

VFB 7

GUARD 8

FEEDB 9

MGU989

Fig.2 Pin configuration.

FUNCTIONAL DESCRIPTION

The TDA4867J consists of a differential input stage, two

output stages, a flyback generator, a protection circuit for

the output stages and a guard circuit.

Differential input stage

The differential input stage has a high CMRR differential

current mode input (pin INP and pin INN) that results in a

high electromagnetic immunity and is especially suitable

for driver units with differential (e.g. TDA485x or SAA4856)

and single-ended current signals.

The differential input stage delivers the driver signals for

the output stages.

In combination with the SAA4856 the power save mode

can be achieved via the input pins without additional

components.

Output stages

The two output stages are current driven in opposite phase

and operate in combination with the deflection coil in a full

bridge configuration. Therefore, the TDA4867J requires no

external coupling capacitor and operates with one supply

voltage (VP) and a separate adjustable flyback supply

voltage (VFB) only. The deflection current through the coil

(Idefl) is measured with the resistor Rm which produces a

voltage drop: Urm ≈ Rm × Idefl. At pin FEEDB a part of Idefl

is fed back to the input stage. The feedback input has a

current input characteristic which holds the differential

voltage between pin FEEDB and pin OUTB on zero.

Therefore the feedback current (IFEEDB) through Rref is:

IFEEDB ≈ R--R---r-m-e--f × Idefl

The input stage directly compares the driver currents into

pins INP and INN with the half of the feedback current

(IFEEDB). Any difference of this comparison leads to a more

or less driver current for the output stages. The relation

between the deflection current and the differential input

current (Ii(dif) = IINP − IINN) is:

Ii(dif) = 2 × IFEEDB ≈ R--R---r-m-e--f × Idefl × 2 or:

Idefl ≈ Ii(dif) × 2----R-×----r-R-e---f-m--

The deflection current can be adjusted up to ±1.25 A by

varying Rref when Rm is fixed to 1 Ω.

Flyback generator

The flyback generator supplies the output stage A during

flyback. This makes it possible to optimize power

consumption (supply voltage VP) and flyback time (flyback

voltage VFB) separately. Due to the absence of a

decoupling capacitor the flyback voltage is fully available.

In parallel with the deflection yoke and the damping

resistor (Rp) an additional capacitor (CSP) and a series

resistor (RSP) have to be used. The flyback time can be

optimized depending on the value of CSP.

2003 Feb 05

4

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