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AN1510
ST video kit for CRT monitor: Optimization of the video performances with input networks
written by ADRIEN BONNAT
The purpose of the present Application Note is to help the designers of the Video board for Monitor to get optimum video performances with the ST Video device kit (PreAmplifier + Amplifiers) in stand alone by using a proper Amplifier Input network.
Although this report is referring to the TDA9210 (Preamplifiers) + STV9556 (7.5ns Amplifier), it is valid for the whole range of the ST stand alone Video devices. (PreAmplifiers TDA9210/9210S./STV9211 and Amplifiers: STV9556/9555/9553 ) .
Note:
The components values hereafter indicated per network are also the ones used on our reference video board to ensure the best matching between the TDA9210 and the STV9556. When using different ST Devices such as TDA92xx/ STV9211+ STV95xx, the values of the network components might be slightly different.
Note also that these values depend on the board layout. It is possible that the parasitical components differ from one layout to another. This also affects the network components. We do not guarantee that the networks presented in this document are usable in a non-ST video system. This network list,which is not exhaustive, shows the common networks used.
Scope
Scope: Purpose: CRT Monitor - Video devices in Stand alone Adjustment of the Networks between the preamplifier and the amplifier to get the optimum video performances.
April 2002
ADCS 7359218
RELEASE NUMBER 1.0
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Measurement conditions
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1
Measurement conditions
The nominal measurement conditions included in this document are the following:
q q q
Video Board: ST EVALCRT51 (ref AB25BX) with TDA9210 + STV9556 Pattern generator: Chroma 2251 (250MHz) Timing: #62 (ADI1280-60) 1280 x 1024, H= 64KHz, V= 60Hz, Pix = 110MHz Pattern: #42 (5 - Mosaic) 5 white square boxes on black background Monitor: VITA 17" 70KHz / (ST7 + TDA9111 + TDA8172) Oscilloscope: Tektronix TDS754A, Digital, 500MHz Probes:

q q q q
Low voltage: Tektronix P6205, active, 10x, 750MHz, <2pF High voltage: Tektronix P5100, passive, 100x, 250MHz, <2.7pF
The following waveforms (Figures 1 and 2) show the video signal on the Red channel, both on the input of the amplifier and on the cathode and with only a 51 resistor between the preamplifier and the amplifier:
Figure 1: Red signals without network
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The 3 networks and their effects
2
2.1
2.1.1
The 3 networks and their effects
Network 1
Description
Figure 2: Network 1
C1 1.5nF
R1 51R C2 10pF
q q
C1 and R1 are adjusted to correct an eventual smear effect and to increase the bandwidth. The C2 capacitor adds a high frequency peaking. It is mandatory that this capacitor matches R1 to avoid the preamplifier overload and the bandwidth downgrading.
Advantages: Network 1 increases the bandwidth. Drawbacks: A small ringing may appear if the bandwidth of the application is already high. Network 1 is used for applications requiring a high bandwidth. It corrects two kinds of smear:
q
Static smear: visible after a "white box" on a black background (or the opposite). This is corrected with C1 // R1. Dynamic smear: visible after a "high frequency pattern" box (1 pixel on 1 pixel off). This is corrected with C2.
q
2.1.2
Effects
The following waveforms (Figures 4 and 5) show the video signal on the Red channel, both on the input of the amplifier and on the cathode.
Figure 3: Red signals with network 1
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The 3 networks and their effects
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2.2
2.2.1
Network 2
Description
Figure 4: Network 2
L1 0.33H
R1 82R C2 10pF
q q
The coil L1 reduces the high bandwidth phenomena, which may disturb the preamp. The capacitor C2 is used to increase the effect of the coil and to add a high frequency peaking.
Advantages: Drastically reduces the high frequency perturbations affecting either the amplifier or the preamplifier. Drawbacks: Slightly reduces the system bandwidth. This network is useful in case of rebound effect (after the overshoot) or in case of high bandwidth cross talk. If some high frequency parasites affect the video performance, using this kind of network can drastically increase the video quality.
2.2.2
Effects
The following waveforms (Figure 7 and 8) show the video signal on the Red channel, both on the input of the amplifier and on the cathode.
Figure 5: Red signals with network 2
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ADCS 7359218
AN1510
The 3 networks and their effects
2.3
2.3.1
Network 3
Description
Figure 6: Network 3
R1 33R C2 15pF
q
The capacitor C2 is used to slightly increase the bandwidth. It also corrects a potential dynamic smear by adding a high frequency peaking. The resistor R1 must match C2 to adjust the peaking without degrading the bandwidth of the system
q
Advantages: Slightly increases the system bandwidth and corrects the dynamic smear. Drawbacks: A good balance between the resistor and the capacitor is necessary to achieve the right effect. Otherwise, network 3 will create the opposite effect. This network can be used in many applications to slightly increase the bandwidth and improve the video quality without modifying the resistors or coils at the amplifier outputs.
2.3.2
Effects
The following waveforms (figures 10 and 11) show the video signal on the Red channel, both on the input of the amplifier and on the cathode.
Figure 7: Red signals with network 3
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3
D3 3 7
Vcc
Green 3 IN2
C23
1N4148 C4 OUT1 110/0.25W 18 In1 Out1 1 11 RK F2 200V R R15 GK F4 200V 110/0.25W G B 100nF R9 R7 51 R6 L1 D5 1N4148 C9 100nF 4 GNDL C33 1.5nF 10pF VCCP 17 R8 15
5V
Vdd
GNDA
GNDS
H2
G1
G2
5
6
8
SCL 10 OSD3 FBLK
RP
R47 100 11 SCL
9
5
7
10 H1
1
GND
VS
R35 100
3
VS
VCO
14
Vco R44 5.6k C34 10nF
C13 100pF
J10 110V J7 C21 10nF/250V optional GND 5V Heater
TDA9210
L4 1H 3.3V SDA 1 2 3 4 I2C R28 0
HFLY R41 100 C2 C37 100F/25V 100nF
4 HFLY
AVDD 13
AVdd
R43 1M
4.7nF/2kV
C14 100nF C19 F3 1.5
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4 In3 110/0.25W Out3 9 9 R45 15k
3.3V
L5 1H
5
DVDD
FBLK
12
C12 100pF
C28 100nF 6
DVSS BOUT 11
G1
R27 150/0.25W
R36 330
D11 1N4004
C20 4.7nF/1kV
R31 30/0.5W
C32
7
TEST GOUT
10
100F/25V
R32 330
8 OVDD ROUT 9
12V 8V 110V J16 C16 47F/25V C15 BLK
3.3V R37 51
R33 330
STV9936
HS1 5V 1 2 3 RadAB20
J8 G2
R34 330 J17 G1 HEATER VS HS HFLY
1 2 3 4 5 6 7 8 47F/25V Power C27 47F/25V
3V0
STMicroelectronics MonitorBusinessUnit - Video application CMG - Imagingand DisplayDivision(IDD) 12, rue JulesHorowitz- B.P. 217 38019Grenoblecedex - FRANCE
7 6 5 4 3 2 1
ABL
ZD1
C27 47F/25V
Sync
EVALCRT52/STV955xdemoboard(AB25)
Version1.4
WednesdayOctober3, 2001
12 GND
SCL
2
15
Rp
GNDP
6/8
HS C1 110V R29 39 8V 12V BLK ABL 100pF R11 2.7 U1 R4 2.7 C26 R25 100 100pF R1 100
C10 C18 4.7F/160V
110V
5V
10nF/250V C8 C7 100nF D2 FDH400 D10 110V 0.33H 110/0.25W FDH400 D7
D1 R2 15 C3 1 IN1 ABL C31 1.5nF HS/CLP 19 BLK 2 20 100nF 5V D4
Test board schematics
Blue
1N4148
47F/25V
J1
R3 75
1N4148
STMicroelectroni cs Confidential
CRT small neck R12 15 5 IN3 6 OUT2 16 GNDP C5 100nF 15 C36 1.5nF R17 51
10pF C24
1 2 3 4 5 6 C6 100nF R13 51 2 In2 110/0.25W 110V 0.33H D12 FDH400 Out2 10
R5 75
D6
video
Red
1N4148
U2 STV9556
R14
D8 C22 100nF
R10 75
FDH400 L2
1N4148
GNDA VCCA D9
C25 10pF
R16 2.7 7
OUT3 SDA SCL FDH400
R40 100 R21 2.7k 12 13 R22 L3 R23 5V R19 2.7k
14
Test board schematics
U3
8
SDA
R38 100
1
SDA
AVSS
16
R46 5.6k C35 10nF
OSD1 OSD2 D13
FDH400
BK F1 200V
0.33H 110/0.25W
R39 100
Rev. C
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Test board layout
4
Test board layout
Figure 8: STV95XX test board
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AN1510
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.
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