Application Notes

APPLICATION NOTE
Application information for
TDA6107JF/07AJF/08JF/08AJF
triple video output amplifiers
AN10227-01
Version 1.2
July 2004
Philips
Semiconductors
E
W
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
ABSTRACT
This report gives a description of the application aspects of the TDA6107JF/07AJF/08JF/08AJF
 Philips Electronics N.V. 2004
All rights are reserved. Reproduction in whole or in part is prohibited without the prior consent
of the copyright owner. The information presented in this document does not form part of any
quotation or contract, is believed to be accurate and reliable and may be changed without
notice. No liability will be accepted by the publisher for any consequence of its use. Publication
thereof does not convey nor imply any license under patent- or other industrial or intellectual
property rights.
2
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
APPLICATION NOTE
Application information for
TDA6107JF/07AJF/08JF/08AJF
triple video output amplifiers
AN10227-01
Authors:
Roland Peters
Pieter van Oosten
Systems & Applications, Innovation Center Nijmegen,
Philips Semiconductors, Consumer Businesses
Keywords
Triple video amplifier
Black current stabilisation
Robust against flashover
Very simple application
Fixed gain
Date: July 2004
3
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
Summary
In this application note you can find an application description of the triple video output amplifiers
with the type numbers TDA6107JF, TDA6107AJF, TDA6108JF and TDA6108AJF. All types
include three video output amplifiers in a DBS9MPF package, version SOT111-1. The types are
all functional the same, but the bandwidth level and gain level is different. A description of the
differences between the types is given. Furthermore the video amplifiers are provided with a
black current measurement output for automatic black current stabilisation. An optimal application
and PCB-layout for flash protection is given.
4
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
TABLE OF CONTENTS:
1.
INTRODUCTION .................................................................................................... 7
2.
FUNCTIONAL PIN DESCRIPTION. ....................................................................... 8
2.1
Input pins 1, 2 and 3. ........................................................................................................................ 8
2.2
Pin 4. .................................................................................................................................................. 8
2.3
Pin 5. .................................................................................................................................................. 9
2.4
Pin 6. ................................................................................................................................................ 10
2.5
Output pins 7, 8 and 9 .................................................................................................................... 10
3.
DISSIPATION AND HEATSINK CALCULATION ................................................ 11
3.1
Dissipation ...................................................................................................................................... 11
3.2
Heatsink calculation ....................................................................................................................... 12
4.
FLASHOVER PROTECTION ............................................................................... 14
4.1
Checklist TDA6107JF / 07AJF for optimal flashover robustness.............................................. 15
4.2
Checklist TDA6108JF / 08AJF for optimal flashover robustness.............................................. 19
5.
THE TDA6107JF / 07AJF AND TDA6108JF / 08AJF REFERENCE / DEMO
BOARD ......................................................................................................................... 23
5
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
LIST OF FIGURES:
Figure 1: Internal circuitry ....................................................................................................................................8
Figure 2: Switch off behaviour...........................................................................................................................10
Figure 3: Thermal resistance..............................................................................................................................12
Figure 4: Power dissipation as a function of the input frequency .................................................................13
Figure 5: Grounding of aquadag and CRT board.............................................................................................14
Figure 6: Application diagram of the TDA6107JF/07AJF ................................................................................15
Figure 7: Optimal CRT PCB-layout with TDA6107JF/07AJF ...........................................................................18
Figure 8: Application diagram TDA6108JF/08AJF ...........................................................................................19
Figure 9: Optimal CRT PCB-layout with TDA6108JF/08AJF ...........................................................................22
Figure 10: Application diagram of the TDA6107JF / 07AJF reference / demo board ...................................23
Figure 11: TDA6107JF / 07AJF reference / demo board layout ......................................................................24
Figure 12: Components TDA6107JF / 07AJF reference / demo board...........................................................25
Figure 13: Application diagram of the TDA6108JF / 08AJF reference / demo board ...................................26
Figure 14: TDA6108JF / 08AJF reference / demo board layout ......................................................................27
Figure 15: Components TDA6108JF / 08AJF reference / demo board...........................................................28
6
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
1. INTRODUCTION
This application note provides a design guide for successful implementation and design-in of the
TDA6107JF/07AJF/08JF/08AJF family. It is meant as a complement of the data sheet, and should not be
used without the specific datasheet of the video amplifier that is being designed in.
The TDA6107JF/07AJF/08JF/08AJF family consists of a complete range of triple video amplifiers to cover
the low and midrange TV sets. All types include three video output amplifiers in a DBS9MPF package,
version SOT111-1.
The features of these amplifiers are:
•
•
•
•
•
•
•
Single package for three amplifiers
One supply voltage
Fixed gain (less spread and saving external resistors)
Black current stabilisation output
Internal flash protection
Low power dissipation
Internal thermal protection
Table 1 gives an overview of the bandwidth and gain factors.
Type
TDA6107JF
TDA6107AJF
TDA6108JF
TDA6108AJF
Typical Gain
Large signal bandwidth
51
81
51
81
4.5 MHz
4.5 MHz
8.0 MHz
8.0 MHz
Table 1
7
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
2. FUNCTIONAL PIN DESCRIPTION.
The internal circuitry of the video amplifier can be seen as an operational amplifier with negative feedback,
see Figure 1 below.
TDA610XX
Rf
Vin
–
Ri
Vout
Ra
+
+
Vref =
2.5V
–
Figure 1: Internal circuitry
2.1 Input pins 1, 2 and 3.
These pins are the inputs of channel 1, 2 and 3.
The internal resistor Ri is given in the datasheet, and can be used to calculate Ra and Rf. This is normally
not useful, however if adding external resistors for EMC reasons or suppressing interference it can be
useful.
The gain and the gain difference depend on the ratio between Rf and Ri, so if the value of Ri changes due
to adding external resistors, the gain will change.
The new gain can be calculated with the following equation.
GNEW =
GSPEC * RISPEC
RISPEC + RS
Where:
GNEW
GSPEC
RISPEC
RS
is the new gain.
is the typical gain mentioned in the datasheet.
is the typical input resistance as mentioned in the datasheet.
is the added series resistance.
We do not recommend to add these extra series resistance, because there will be a bigger spread in gain
between products due to the spread in Ri.
Furthermore adding extra series resistance makes the step response worse. This means that the ringing
and overshoot will increase.
2.2 Pin 4.
This pin is the ground connection of the amplifier. It should be directly connected to the small signal GND,
with a trace as short as possible (see chapter 4).
8
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
2.3 Pin 5.
Pin 5 is the black current measurement output of the amplifier. The current flowing out of this pin is
equivalent to the sum of the currents flowing in the cathodes of the CRT (between certain limits). This
output is intended to be used in the cathode calibration loop (black current stabilization), but can also be
used for discharging the CRT after set switch-off (except the TDA6108JF). This pin can be directly
connected to the TV-signal processor, but for stability it is allowed to add a series resistance and a
capacitor to ground. When calculating this RC combination, keep in mind that the output must be stable
within 39µs (due to timing of the TV-signal processor) after start of the measurement line.
Another possibility to minimize disturbances is to shield the return wire and to embed the Iom track in a
ground plane on the PCB layout.
The maximum average current for the TDA6108AJF must be limited to 5.6mA; therefore a series
resistance must be used. An internal zener diode is connected to the Iom pin, and limits the voltage of this
output between 6V and 10V. By means of this data, the minimal value of the resistor can be calculated
with:
R min =
Vomclamp max − Vbias
Iom max
Where:
VOMCLAMPmax
VBIAS
IomMAX
is the maximal clamp voltage of the internal zener diode
is the minimal bias voltage of the Iom input of the TV-signal processor
is the maximal allowed average current of the RGB amplifier
For the TDA110XXH/TDA120XXH family (UOCIII series) this results in a minimal resistance of:
R min =
10V − 3V
= 1250Ω
5.6mA
The maximal value of this resistor is determined by the TV-signal processor. If the resistor value is chosen
too high, the feedback current will be influenced.
As the voltage drop across the resistor will be too high and thus the zener diode will conduct and therefore
a part of the current will flow through the zener diode instead of into the TV-signal processor. The maximal
value can be calculated by:
Vomclamp min − Vbias
R max =
Imax
Where:
VOMCLAMPmin
VBIAS
IMAX
is the minimal clamp voltage of the internal zener diode
is the minimal bias voltage of the Iom input of the TV-signal processor
is the maximal current running into the TV-signal processor during discharge or during a
measuring line (if no discharge function is used).
For the TDA110XXH/TDA120XXH family (UOCIII series) this results in a maximal resistance of:
R max =
6 − 3V
= 3kΩ
1mA
9
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
TDA6107A / TDA6108A
–
Vin
+
+
Vref
–
6V-10V
Iom
1k2
560pF
&
Fixed
current
discharge
1 mA
During a transition of the video signal, there will be some voltage spikes on the Iom output. These spikes are
a result of fast charging and discharging parasitic capacitance. The amplitude of the spikes is limited to the
clamp voltage of the internal zener diode and will cause no problems.
2.4 Pin 6.
This pin is the VDD connection, it must be decoupled to ground with a capacitor and an electrolytic capacitor
to ground, to protect the video amplifier for flashover, see the chapter 4
2.5 Output pins 7, 8 and 9
These are the outputs of channel 3, 2 and 1, with a defined switch-off behavior.
These pins stay under control of the input voltage even for low values of VDD. This means that the output
voltage VOC follows the discharge curve of VDD when the TV set is switched off. See Figure 2: Switch off
behaviour.
1
2
CH 1
50V
CH2
5 0V
M 250m s C H 1
Figure 2: Switch off behaviour
10
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
3. DISSIPATION AND HEATSINK CALCULATION
3.1 Dissipation
The total amount of dissipation in the triple video amplifiers consists of a sum of two powers.
The first part is the static dissipation, which is the result of the quiescent current and can be calculated
with:
PSTAT = VDD * IDD + 3 * (VOCdc * IOCdc )
Where:
VDD
IDD
VOCdc
IOCdc
is the supply voltage.
is the supply current.
is the value of the cathode offset.
is the value of the dc output current.
The second part is the dynamic dissipation, which is a result of continuously switching of the internal
circuitry and thus charging and discharging of on-chip parasitic and load capacitance.
For a sinusoidal signal, it can be calculated with:
PDYN


1
= 3 * VDD * CTOT * fIN * VOCpp * δ *

fIN

1+
BL







Where:
VDD
CTOT
fIN
VOCpp
δ
BL
is the supply voltage.
is the sum of the internal- and load capacitance.
Frequency of the input signal.
Peak to peak AC component of the output signal.
Non-blanking duty cycle.
Large signal bandwidth of the video amplifier.
This formula however is not representative for a real condition in a TV set. A nominal TV picture consists of
a complex variety of signals. If we would use these formulas to calculate a heatsink, the heatsink would be
far too big and too expensive. So to calculate a proper heatsink, it is better to see what the video amplifier
dissipates in a worst-case condition.
Figure 4 shows the power dissipation as a function of the input frequency. The test conditions for these
graphs are given in Table 3: Test conditions.
All video amplifiers are equipped with an internal thermal protection. This circuit gives a decrease of the
slew rate if the temperature of the die is higher than 130°C. This prevents thermal ageing and reduces the
necessary heatsink size. Taking this into account, the worst-case condition whereby the slew rate should
not be influenced is a multiburst video signal. So the heatsink should be calculated for this condition.
11
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
3.2 Heatsink calculation
How the heatsink can be calculated is shown underneath.
Ptot
TJMAX − TA
− (RTH , J − F + RTH , F − H )
RTH , H − A =
PTOT
Tj
Rth,j-f
Where:
RTH,H-A
RTH,J-F
RTH,F-H
TJMAX
TA
PTOT
Rth,f-h
is the thermal resistance from heatsink to ambient.
is the thermal resistance from junction to fin.
is the thermal resistance from fin to heatsink.
is the maximum junction temperature.
is the ambient temperature in a TV set.
is the total of dissipated power.
Rth,h-a
Ta
Figure 3: Thermal resistance
The value for RTH,J-F can be found in the datasheet, which is 11K/W for the DBS9MPF (SOT111-1)
package. The value for RTH,F-H depends on the mounting method and will be under normal conditions about
0.5K/W.
TJMAX is the temperature where the internal thermal protection starts to operate, and is approximately
130°C. The maximum ambient temperature in a TV set can be about 65°C, and PTOT can be found in
Figure 4.
Using this equation for the TDA6108AJF, this would result in a heatsink with a thermal resistance of at
least 13.9K/W. The power curves given in Figure 4, are typical values, considering this, we should subtract
2K/W because of the variation in power dissipation. To minimise the dissipated power, it is advised to use
the supply voltage VDD as low as possible.
Table 2 gives a summery for the recommended heatsink values.
Amplifier type:
TDA6107JF/TDA6107AJF
TDA6108JF/TDA6108AJF
Power
(multiburst)
Calculated heatsink value
1.9W
2.56W
21.5 K/W
12 K/W
Table 2
12
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
Typical performance characteristics.
Table 3: Test conditions
VDD = 200V
Type
VOCdc = 100V
VOCpp
TDA6107JF/AJF
TDA6108JF/AJF
100
100
δ=0.8
CTOT
4.5 pF
5.3 pF
P=f(Fsin) (80% because of Fly Back)
4,00
TDA6108AJF
3,50
3,00
TDA6108JF
Ptot (W)
2,50
2,00
TDA6107JF
TDA6107AJF
1,50
1,00
0,50
0,00
0
1000
Nominal Picture
2000
3000
Multiburst
4000
Noise
5000
6000
7000
8000
F (kHz)
Figure 4: Power dissipation as a function of the input frequency
13
9000
10000
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
4. FLASHOVER PROTECTION
A picture tube has generally several high voltage discharges (flashovers) in its lifetime. During the
flashovers, a high voltage will be present on the cathodes. The video amplifier must be protected from
these flashovers. For optimal flashover protection the grounding wire from aquadag to CRT-board and from
CRT-board to main board must be connected like in Figure 5 below.
Vdd
CRT-board
C1
D1
100nF BAV21
250V
C2
10uF
250V
6
7,(8,9)
3x
EHT
R1
100 ohm
R FLASH
KB
video amplifier
Spark gap
KG
G2
KR
4
G1
G3
f f
aquadag
To GND of main board close to LOT/FBT
To GND of main board
Figure 5: Grounding of aquadag and CRT board.
The TDA6107JF / 07AJF does not need an external flash protection, when RFLASH is larger than 1k. The
TDA6108JF / 08AJF always needs external flash protection to protect against flashovers. The external
flash protection consists of an external diode D1 and external resistor R1. The diode clamps the output
voltage to the VDD. To limit the diode current an external surge resistor (high voltage resistor) RFLASH must
be used together with a 2kV spark gap. A more detailed description about the external flash protection is
given in the checklist in the next paragraph: 4.1.
14
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
4.1 Checklist TDA6107JF / 07AJF for optimal flashover robustness
C3
220pF - 4.7nF
250V
2
TV-signal
processor
Vi(2)
R3
100 ohm
R FLASH3
1k5 / 0.5W
R2
100 ohm
8
Voc(2)
R1
100
ohm
9
RFLASH2
1k5 / 0.5W
7
Voc(3)
Vi(3)
TDA6107JF/
07AJF
1
C2
C4
10uF
220pF - 2.7nF
250V
250V
D3 *1
BAV21
D2
BAV21
D1
BAV21
C1
100 nF
VDD 6 250V
3
R4
47 ohm - 100 ohm
RFLASH1
1k5 / 0.5W
V
Vi(1)
Internal block diagram oc(1)
5
is drawn in the
Iom datasheet on page 2
4 GND
EHT
KB
KG
KR
f f
C5
1nF
2kV
*1 = D1,2,3 and R1,2,3 only needed when RFLASH1,2,3 =< 1k5
VDD = 200V
G1 G2 G3
R5
1k5 / 0.5W
= Small signal GND
VG2
= Large signal GND
Figure 6: Application diagram of the TDA6107JF/07AJF
Checklist:
TDA6107JF / 07AJF
1.
2.
Recommended value
/ type
Grounding of the CRT PCB-layout
On the CRT PCB-layout the
large signal GND must be
isolated from the small signal
GND. So pin 4 GND of the
TDA6118JF must not be
connected directly to the
spark gap GND (focus, G2
and cathodes) of the CRTsocket. See Figure 7.
It is also strongly
recommended to place no
components (capacitors,
resistors and coils) between
the small signal GND and the
large signal GND. See Figure
7.
15
Explanation
Prevents that large flashover voltage /
current peaks can directly flow through the
small signal GND.
Prevents that large flashover voltage /
current peaks can directly flow through the
small signal GND
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
3.
4.
5.
6.
7.
8.
9.
Application Note
AN10227-01
Ground loops in the small
Ground loops could reveal in large voltage
signal GND must be avoided.
peaks due to long tracks. V = L*di/dt
So pin 4 GND must have one
generated during a flashover
connection to the connector
to the main board. See
Figure 7.
Small signal ground track
To avoid current / voltage peaks at pin 4
must be around the
GND during a flashover.
TDA6107JF / 07AJF. See
Figure 7.
External protection components, decoupling circuits
High frequency decoupling
100nF / 250V
C1 has to reduce fast large voltage peaks
capacitor, C1
between pin 6 VDD and pin 4 GND due to V
= L*di/dt. (See points x + x for optimal PCB
layout)
Low frequency current peaks from a
Low frequency decoupling
• 4.7uF / 250V for
flashover flows via D1, D2 and D3 into C2.
capacitor, C2
≤21 inch picture
tube size
• 10uF / 250V for
>21 inch picture
tube size
High frequency decoupling
220pF - 2.7nF / 250V
C3 has to reduce fast large voltage peaks
capacitor, C3
between pin 6 VDD and pin 4 GND due to V
= L*di/dt.
Series resistor, R4
In combination with C3 and C4 for optimal
47Ω - 100Ω / 0.25W
flash robustness.
High frequency decoupling
220pF - 2.7nF / 250V
C4 has to reduce fast large voltage peaks
capacitor, C4
between pin 6 VDD and pin 4 GND due to V
= L*di/dt.
All external capacitors of the TDA6107JF / 07AJF application must be grounded to the small signal
GND
The value of C3, C4 and R4 depend on the layout of the CRT-board. During a flashtest can be checked
which values give the lowest voltage peaks between pin 6 VDD and pin 4 GND. These voltage peaks can be
measured with a digital oscilloscope with probes and grounding as close as possible to pin 6 VDD and pin 4
GND. A special provision can be made on the probe to be close to the pins. It is very important that the
grounding wire of the probe is short for not picking up spikes in the GND.
10.
External protection components, diodes and resistors
Flash resistor, RFLASH
1.5kΩ / 0.5W surge
•
=> Always needed in
resistor (high voltage
•
application
resistor). RFLASH must
be capable of handling •
large peak voltages
from a flashover
•
16
Limits flashover current peaks
When the value is larger than 1.5kΩ,
the bandwidth will be reduced.
When the value is smaller than 1.5kΩ,
larger than 3A flash current peaks can
be expected and external flash
protection (D1 + R1) must be used.
When the value ≥ 1.5kΩ, a maximum
value of 3A flash current peaks can be
expected and the external flash
protection (D1 + R1) is NOT needed.
The internal flash diodes are capable
of handling a maximum value of 3A
flash current peaks.
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
11.
Diode, D1, D2 and D3
=> Only needed when the
value of RFLASH is lower than
1.5kΩ
12.
Resistor, R1, R2 and R3
=> Only needed when the
value of RFLASH is lower than
1.5kΩ
Resistor, R5
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
Application Note
AN10227-01
BAV21 or equivalent.
D1 must have a fast
transient response,
low shunt capacitance
and capable of
handling large peak
currents from a
flashover.
100Ω / 0.25W
D1, D2 and D3 clamp the output to the VDD
supply during a flashover.
Limits current into video amplifier
1.5kΩ / 0.5W surge
Limits flashover current peaks on the CRTresistor (high voltage
board
resistor). R5 must be
capable of handling
large peak voltages
from a flashover
Optimal PCB-layout to have optimal flash robustness
If D1, D2 and D3 are needed, <5mm
A small discharge loop. The track between
the cathodes of D1, D2 and
diodes and capacitor must be short to
D3 must be close to C1 in the
avoid high voltages V = L*di/dt generated
layout. See Figure 7 below.
during a flashover.
C1 must be as close as
<5mm
Prevent that large flashover voltage /
possible to pin 6 VDD and pin
current peaks can directly flow through the
4 GND of the video amplifier.
small signal GND.
See Figure 7 below.
Distance of G2, G1, R, G and > 3 mm
Prevent arcing during flash over.
B copper tracks to adjacent
tracks
G2 CRT pins must have 2
Prevent arcing during flash over.
slots cut on the PCB to
increase the distance from
the adjacent R and B pins.
No copper track in between
Prevent arcing during flash over.
CRT pins.
No sharp edges on the
Prevent arcing during flash over.
copper track.
Large signal GND and (if
Prevent arcing during flash over.
> 2mm
used) EHT info track distance
must be 2mm from all other
tracks.
CRT wire between aquadag
A small discharge loop during flashover.
layer and CRT-board must
be as short as possible.
CRT wire between aquadag
Low impedance discharge loop during
layer and CRT-board must
flashover.
not be too thin.
17
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
Figure 7 shows the optimal CRT PCB-layout for good flashover robustness.
Figure 7: Optimal CRT PCB-layout with TDA6107JF/07AJF
18
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
4.2 Checklist TDA6108JF / 08AJF for optimal flashover robustness
C3
220pF - 2.7nF
250V
R4
47 ohm - 100 ohm
D3
BAV21
VDD 6
7
3
V i(3)
TV-signal
processor
2
V i(2)
1
V i(1)
5
I om
D2
BAV21
D1
BAV21
C1
100 nF
250V
Voc(3)
TDA6108JF/
08AJF
Internal block diagram
is drawn in the
datasheet on
page 2
8
Voc(2)
9
VDD = 200V
C2
10uF
250V
R3
100 ohm
R FLASH3
1k / 0.5W
R2
100 ohm
R FLASH2
1k / 0.5W
R1
100 ohm
R FLASH1
1k / 0.5W
Voc(1)
4 GND
C4
220pF - 2.7nF
250V
EHT
KB
KG
KR
f f G1 G2 G3
C5
1nF
2kV
= Small signal GND
= Large signal GND
R5
1k5 / 0.5W
VG2
Figure 8: Application diagram TDA6108JF/08AJF
Checklist:
TDA6108JF / 08AJF
1.
2.
3.
Recommended value
/ type
Grounding of the CRT PCB-layout
On the CRT PCB-layout the
large signal GND must be
isolated from the small signal
GND. So pin 4 GND of the
TDA6108JF / 08AJF must
not be connected directly to
the spark gap GND (focus,
G2 and cathodes) of the
CRT-socket. See Figure 9.
It is also strongly
recommended to place no
components (capacitors,
resistors and coils) between
the small signal GND and the
large signal GND. See Figure
9.
Ground loops in the small
signal GND must be avoided.
So pin 4 GND must have one
connection to the connector
to the main board. See
Figure 9.
19
Explanation
Prevents that large flashover voltage /
current peaks can directly flow through the
small signal GND.
Prevents that large flashover voltage /
current peaks can directly flow through the
small signal GND
Ground loops could reveal in large voltage
peaks due to long tracks. V = L*di/dt
generated during a flashover
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
4.
5.
Small signal ground track
must be around the
TDA6108JF / 08AJF. See
Figure 9.
External protection components, decoupling circuits
High frequency decoupling
100nF / 250V
capacitor, C1
6.
Low frequency decoupling
capacitor, C2
7.
High frequency decoupling
capacitor, C3
8.
9.
Application Note
AN10227-01
•
4.7uF / 250V for
≤21 inch picture
tube size
• 10uF / 250V for
>21 inch picture
tube size
220pF – 2.7nF / 250V
To avoid current / voltage peaks at pin 4
GND during a flashover.
C1 has to reduce fast large voltage peaks
between pin 6 VDD and pin 4 GND due to V
= L*di/dt. (See points x + x for optimal PCB
layout)
Low frequency current peaks from a
flashover flows via D1, D2 and D3 into C2.
C3 has to reduce fast large voltage peaks
between pin 6 VDD and pin 4 GND due to V
= L*di/dt.
Series resistor, R4
In combination with C3 and C4 for optimal
47Ω - 100Ω / 0.25W
flash robustness.
High frequency decoupling
220pF – 2.7nF / 250V
C4 has to reduce fast large voltage peaks
capacitor, C4
between pin 6 VDD and pin 4 GND due to V
= L*di/dt.
All external capacitors of the TDA6108JF / 08AJF application must be grounded to the small signal
GND
The value of C3, C4 and R4 depend on the layout of the CRT-board. During a flashtest can be checked
which values give the lowest voltage peaks between pin 6 VDD and pin 4 GND. These voltage peaks can be
measured with a digital oscilloscope with probes and grounding as close as possible to pin 6 VDD and pin 4
GND. A special provision can be made on the probe to be close to the pins. It is very important that the
grounding wire of the probe is short for not picking up spikes in the GND.
10.
11.
12.
13.
External protection components, diodes and resistors
Flash resistor, RFLASH
1kΩ / 0.5W low ohmic
• Limits flashover current peaks
=> Always needed in
surge resistor (high
• When the value is larger than 1kΩ, the
application
voltage resistor).
bandwidth will be reduced.
RFLASH must be
• When the value is smaller than 1kΩ,
capable of handling
larger than 5A flash current peaks can
large peak voltages
be expected.
from a flashover
Diode, D1, D2 and D3
BAV21 or equivalent.
D1, D2 and D3 clamp the output to the VDD
=> Always needed in
supply during a flashover.
D1 must have a fast
application
transient response,
low shunt capacitance
and capable of
handling large peak
currents from a
flashover.
Resistor, R1, R2 and R3
Limits flashover current peaks on the CRT100Ω / 0.25W
=> Always needed in
board
application
Resistor, R5
1.5kΩ / 0.5W surge
Limits flashover current peaks on the CRTresistor (high voltage
board
resistor). R5 must be
capable of handling
large peak voltages
from a flashover
20
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
14.
15.
16.
17.
18.
19.
20.
21.
22.
Application Note
AN10227-01
Optimal PCB-layout to have optimal robustness
If D1, D2 and D3 are needed, <5mm
the cathodes of D1, D2 and
D3 must be close to C1 in the
layout. See Figure 9 below.
C1 must be as close as
<5mm
possible to pin 6 VDD and pin
4 GND of the video amplifier.
See Figure 9 below.
Distance of G2, G1, R, G and > 3 mm
B copper tracks to adjacent
tracks
G2 CRT pins must have 2
slots cut on the PCB to
increase the distance from
the adjacent R and B pins.
No copper track in between
CRT pins.
No sharp edges on the
copper track.
Large signal GND and (if
> 2mm
used) EHT info track distance
must be 2mm from all other
tracks.
CRT wire between aquadag
layer and CRT-board must
be as short as possible.
CRT wire between aquadag
layer and CRT-board must
not be too thin.
21
A small discharge loop. The track between
diodes and capacitor must be short to
avoid high voltages V = L*di/dt generated
during a flashover.
Prevent that large flashover voltage /
current peaks can directly flow through the
small signal GND.
Prevent arcing during flash over.
Prevent arcing during flash over.
Prevent arcing during flash over.
Prevent arcing during flash over.
Prevent arcing during flash over.
A small discharge loop during flashover.
Low impedance discharge loop during
flashover.
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
Figure 9 shows the optimal CRT PCB-layout for good flashover robustness.
Figure 9: Optimal CRT PCB-layout with TDA6108JF/08AJF
22
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
5. THE TDA6107JF / 07AJF AND TDA6108JF / 08AJF REFERENCE /
DEMO BOARD
The TDA6107JF / 07AJF reference board is shown in Figure 11 and Figure 12. The TDA6108JF / 08AJF
has its own reference / demo board and is shown in Figure 14 and Figure 15. These boards are meant for
evaluation and demonstration purposes.
R1
1E2
C5
220pF - 2n7
500V
TDA6107(A)JF
1 2 3 4 5 6 7 8 9
C4
4u7 - 10u
250V
KB
KG
KR
R4
1k5
5
4
3
2
R5
1k5
1
R6
47E - 100E
C6
220pF - 2n7
500V
ff
GND
4
5
6
AQUA
Vdd
EHT
R3
1k5
X1
Blue
Green
Red
GND
Iom
X2
1
2
3
G2
G1 G3
f f
C3
100nF
250V
C2
2n7
500V
R7
1k
R2
1k5
Vg2
Aqua
C1
1n
2kV
Figure 10: Application diagram of the TDA6107JF / 07AJF reference / demo board
When the TDA6107JF / 07AJF is used with 1k5 flash resistor (R3, R4, R5), the external flash diodes are
not needed. If the TDA6107JF / 07AJF is used with 1k flash resistors, external flash diodes + 100Ω
resistors must be used. See for a detailed description section 4.1. For the TDA6107JF / 07AJF with
external flash protection, the TDA6108JF / 08AJF reference / demo must be used.
G1 is connected to the small signal GND via a 1k flash resistor.
23
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
TDA6107JF / 07AJF reference / demo board (layout side)
Figure 11: TDA6107JF / 07AJF reference / demo board layout
This reference / demo board has an option to use the aquadag ground for the EHT info. This can be done
by leaving out the jumper wire above connector X2. Then the aquadag ground is isolated from the large
signal ground (heater and VG2 decoupling capacitor).
24
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
TDA6107JF / 07AJF reference / demo board (component side)
Figure 12: Components TDA6107JF / 07AJF reference / demo board
On this TDA6107JF / 07AJF reference / demo board a 15.2 K/W heatsink is mounted, however a smaller
heatsink of 21.5K/W would be sufficient for the TDA6107JF / 07AJF. See section: 3.2
25
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
Application diagram of the TDA6108JF / 08AJF reference / demo board:
R1
1E2
C5
220pF - 2n7
500V
C4
10uF
250V
X1
5
4
3
2
Blue
Green
Red
GND
1
Iom
R8
D1
100E BAV21
R3
1k
R9
100E
R4
1k
R10
100E
D2
BAV21
D3
BAV21
R5
1k
ff
GND
4
5
6
AQUA
Vdd
R6
47E - 100E
C6
220pF - 2n7
500V
TDA6108(A)JF
1 2 3 4 5 6 7 8 9
X2
1
2
3
KB
KG
KR
EHT
G2
G1 G3
f f
C3
100nF
250V
C2
2n7
500V
R7
1k
R2
1k5
Vg2
C1
1n
2kV
Figure 13: Application diagram of the TDA6108JF / 08AJF reference / demo board
External flash diodes must always be used with the TDA6108JF / 08AJF.
G1 is connected to the small signal GND via a 1k flash resistor.
26
Aqua
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
TDA6108JF / 08AJF reference / demo board (layout side)
Figure 14: TDA6108JF / 08AJF reference / demo board layout
This reference / demo board has an option to use the aquadag ground for the EHT info. This can be done
by leaving out the jumper wire above connector X2. Then the aquadag ground is isolated from the large
signal ground (heater and VG2 decoupling capacitor).
27
Philips Semiconductors
TDA6107JF/07AJF/08JF/08AJF
Triple video output amplifiers
Application Note
AN10227-01
TDA6108JF / 08AJF reference / demo board (component side)
Figure 15: Components TDA6108JF / 08AJF reference / demo board
On this TDA6108JF / 08AJF reference / demo board a 12 K/W heatsink is mounted, which is sufficient for
the TDA6108JF / 08AJF. See section: 3.2.
28
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Contact information
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Fax: +31 40 27 24825
For sales offices addresses send e-mail to: [email protected]
© Koninklijke Philips Electronics N.V. 2002
SCB74
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