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TDA6111

Video output amplifier

Philips Electronics 

Philips Semiconductors

Video output amplifier

Preliminary specification

TDA6111Q

TEST AND APPLICATION INFORMATION

Dissipation

Regarding dissipation, distinction must first be made

between static dissipation (independent of frequency) and

dynamic dissipation (proportional to frequency).

The static dissipation of the TDA6111Q is due to high and

low voltage supply currents and load currents in the

feedback network and CRT.

The static dissipation equals:

Pstat = VDDL × IDDL + VDDH × IDDH

+

Voc

×

Ioc

–

Vfb

×







R-V----ff--bb-







Rfb = value of feedback resistor.

Ioc = DC value of cathode current.

With Vfb = Voc = 100 V, Rfb = 68 kΩ, Ioc = 0.6 mA and

other typical conditions as mentioned in Chapter

“Characteristics”, the static dissipation Pstat = 2.0 W.

The dynamic dissipation equals:

Pdyn = VDDH × (CL + Cfb + Cint) × fi × Vo(p-p) × δ

CL = load capacitance.

Cfb = feedback capacitance (≈ 150 fF).

Cint = internal load capacitance (≈ 4 pF).

fi = input frequency.

Vo(p-p) = output voltage (peak-to-peak value).

δ = non-blanking duty-cycle (≈ 0.8).

With CL = 10 pF, Cfb = 0, Cint = 4 pF, fi = 8 MHz

(simulation of worst-case noise), Vo(p-p) = 100 V and

δ = 80% then Pdyn = 1.8 W

The IC must be mounted on the picture tube base print to

minimize the load capacitance (CL).

The total power dissipation, Ptot = Pstat + Pdyn thus

amounts to 3.6 W under given conditions.

From Tj = Tamb + Ptot × Rth j-a < Tj(max) = 150 °C, Rth j-a of

the package and heatsink together must be < 24 K/W.

1995 Feb 07

11

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