tda8358j-n2 NXP Semiconductors, tda8358j-n2 Datasheet - Page 13

• Manufacturer Part Number: tda8358j-n2
• Description: Full Bridge Vertical Deflection Output Circuit In Lvdmos With East-west Amplifier
• Manufacturer: NXP Semiconductors

Philips Semiconductors
The flyback supply voltage calculated this way is
approximately 5% to 10% higher than required.
Calculation of the power dissipation of the vertical
output stage
The power dissipation of the vertical output stage is given
by the formula:
P
The power to be supplied is given by the formula:
In this formula 0.3 [W] represents the average value of the
losses in the flyback supply.
The average external load power dissipation in the
deflection coil and the measuring resistor is given by the
formula:
Example
Table 1 Application values
Table 2 Calculated values
2002 Sep 25
P
P
I
I
L
R
R
f
t
V
R
t
x
V
P
P
P
V
coil(peak)
coil(p-p)
vert
FB
vert
sup
L
coil
P
FB
sup
L
V
Full bridge vertical deflection output circuit
in LVDMOS with east-west amplifier
coil
M
M
= P
=
+ R
SYMBOL
SYMBOL
=
------------------------------- -
sup
I
coil peak
coil
V
P
(hot)
3
P
L
I
----------------------- -
coil peak
2
2
R
+
coil
0.000641
VALUE
VALUE
V
0.02
8.91
3.74
5.17
P
640
+
1.2
2.4
0.6
7.8
50
14
30
5
6
R
0.015 [A]
M
+
0.3 [W]
UNIT
UNIT
mH
Hz
W
W
W
A
A
V
V
s
s
13
Power dissipation calculation for the east-west stage
In general the shape of the east-west output wave form is
a parabola. The output voltage will be higher at the
beginning and end of the vertical scan compared to the
voltage at the scan middle, while the output current will be
higher at the scan middle. This results in an almost uniform
power dissipation distribution during scan. Therefore the
power dissipation can be calculated by multiplying the
average values of the output voltage and the output
current of pin OUTEW.
When verifying the dissipation the switch-on and switch-off
dissipation should also be taken into account. Power
dissipation during start-up can be 3 to 5 times higher than
during normal operation.
Heatsink calculation
The value of the heatsink can be calculated in a standard
way with a method based on average temperatures. The
required thermal resistance of the heatsink is determined
by the maximum die temperature of 150 C. In general we
recommend a design for an average die temperature
not exceeding 130 C. It should be noted that the
heatsink thermal resistance R
standard calculation will be lower then normally found for
a vertical deflection stand alone device, due to the
contribution of the EW power dissipation to this value.
E
Measured or known values:
P
R
The required heatsink thermal resistance is given by:
When we use the values known we find:
The heatsink temperature will be:
T
R
R
h
XAMPLE
EW
th(j-c)
th h a
th h a
= T
= 3 W; P
–
–
amb
= 4 K/W; R
=
=
+ R
------------------------ -
P
130 40
--------------------- -
T
V
EW
th(h-a)
j
3
–
= 6 W; T
+
T
–
+
th(c-h)
6
amb
P
V
–
P
–
tot
= 1 K/W.
amb
4
R
= 40 + 5
+
th j c
1
= 40 C; T
th(h-a)
–
=
+
5 K/W
found by performing a
R
9 = 85 C
Product specification
th c h
j
TDA8358J
= 130 C;
–