TDA8153 데이터 시트보기 (PDF) - STMicroelectronics
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TDA8153 Datasheet PDF : 11 Pages
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TDA8153
Power Dissipation
Taking as reference the IC internal schematic dia-
gram we can calculate the power dissipated by the
video amplifiers.
The power dissipation of the IC is defined by a static
an a dynamic part.
The statically dissipated power is given by :
PS
=
3
Vht
Vht − Vobl
R1
+
Vobl
Rf
−
3
Vobl2
Rf
−
3
(Vref
+ 2Vbe)2
Rb
Where Rf is the feedback resistance and Rb the
input to ground resistance with a black level
Vobl = 150V, Vht = 200V, Rf = 68kΩ and Rb = 1.8kΩ
we have : PS = 1.75W
The dynamic power dissipation has been calcu-
lated with a 5MHz, 80Vpp sinusoidal output signal
and a load capacitor CL = 10pF with the following
expression :
Pd
=
0.8
Vht
(2f
CL
Vop)
−
0.8
Vop2
2Rf
=
1.90W
The value is reduced by 20% (0.8 factor) because
during the flyback time there is not signal.
The total power dissipated by the IC is therefore :
PT = PS + Pd = 1.75 + 1.90 = 3.65W
One of the worst working condition of the TV set as
regards the power dissipation, is when you get
white noise on the screen, for example, when you
disconnect the TV aerial or the channels are not
properly tuned.
In these cases if we set the TV receiver for 80VPP
Figure 5 : Mounting Examples
white noise output signal with a black level
Vob1 = 125V, the total power dissipated by the IC
can be measured.
It results about PT = 4.8W.
With a maximum ambient temperature of 70°C and
a junction temperature of 150°C a 15°C/W heatsink
is required.
Figure 4 : Maximum Allowable Power Dissipation
versus Ambient Temperature
10/11
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