LM2429TE [TI]
IC,VIDEO AMPLIFIER,TRIPLE,BIPOLAR,ZIP,11PIN,PLASTIC;
| 型号： | LM2429TE |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | IC,VIDEO AMPLIFIER,TRIPLE,BIPOLAR,ZIP,11PIN,PLASTIC 放大器 |
| 文件： | 总12页 (文件大小：721K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
October 2004
LM2429
Monolithic Triple Channel 15 MHz DTV Driver
General Description
Features
n 0V to 5V input range
The LM2429 is an integrated high voltage CRT driver circuit
designed for use in DTV applications. The IC contains three
high input impedance, wide band amplifiers which directly
drive the RGB cathodes of a CRT. Each channel has its gain
internally set to −51 and can drive CRT capacitive loads as
well as resistive loads present in other applications, limited
only by the package’s power dissipation.
n Greater than 130VPP output swing capability
n Stable with 0–20 pF capacitive loads and inductive
peaking networks
n Convenient TO-220 staggered thin lead package style
Applications
The IC is packaged in an industry standard 11-lead TO-220
molded plastic power package designed specifically to meet
high voltage spacing requirements. See Thermal Consider-
ations section.
n AC coupled DTV applications using the 480p format as
well as standard NTSC and PAL formats.
Connection Diagram
Schematic Diagram
20073102
Note: Tab is at GND
Top View
Order Number LM2429
20073101
FIGURE 1. Simplified Connection and Pinout Diagram
FIGURE 2. Simplified Schematic Diagram
(One Channel)
© 2004 National Semiconductor Corporation
DS200731
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Absolute Maximum Ratings (Notes 1,
3)
Operating Ranges (Note 2)
VCC
+130V to +180V
+7V to +13V
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
VBB
VIN
+0V to +4V
VOUT
+15V to +175V
Refer to Figure 11
Supply Voltage (VCC
)
+200V
+15V
Case Temperature
Bias Voltage (VBB
)
)
Do not operate the part without a heat sink.
Input Voltage (VIN
-0.5V to VBB +0.5V
−65˚C to +150˚C
Storage Temperature Range (TSTG
Lead Temperature
)
<
(Soldering, 10 sec.)
300˚C
ESD Tolerance,
Human Body Model
Machine Model
Junction Temperature
θJC (typ)
2kV
200V
150˚C
2.9˚C/W
Electrical Characteristics
(See Figure 3 for Test Circuit) Unless otherwise noted: VCC = +180V, VBB = +8V, CL = 8pF, TC = 50˚C. DC Tests: VIN
=
2.5VDC. AC Tests: Output = 130VPP (35V - 165V) at 1MHz.
LM2429
Symbol
ICC
Parameter
Supply Current
Conditions
Units
Min
Typical
Max
All Three Channels, No Input Signal,
No Output Load
16
30
mA
IBB
Bias Current
All Three Channels
12
105
168
-51
1.0
8
17
mA
VDC
VDC
VOUT, 1
VOUT, 2
AV
DC Output Voltage
DC Output Voltage
DC Voltage Gain
Gain Matching
Linearity Error
Rise Time
No AC Input Signal, VIN = 2.5VDC
No AC Input Signal, VIN = 1.2VDC
No AC Input Signal
100
163
-48
110
173
-54
∆AV
LE
(Note 4), No AC Input Signal
(Notes 4, 5), No AC Input Signal
(Note 6), 10% to 90%
dB
%
tR
26
30
5
ns
ns
%
tF
Fall Time
(Note 6), 90% to 10%
OS
Overshoot
(Note 6)
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.
Note 2: Operating ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. For guaranteed specifications and
test conditions, see the Electrical Characteristics. Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis. The guaranteed
specifications apply only for the test conditions listed. Some performance characteristics may change when the device is not operated under the listed test
conditions.
Note 3: All voltages are measured with respect to GND, unless otherwise specified.
Note 4: Calculated value from Voltage Gain test on each channel.
Note 5: Linearity Error is the variation in DC gain from V = 1.1V to V = 3.8V.
IN
IN
<
f
Note 6: Input from signal generator: t , t
1 ns.
r
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2
AC Test Circuit
20073103
Note: 8pF load includes parasitic capacitance.
FIGURE 3. Test Circuit (One Channel)
Figure 3 shows a typical test circuit for evaluation of the LM2429. This circuit is designed to allow testing of the LM2429 in a 50Ω
environment without the use of an expensive FET probe. The two 4990Ω resistors form a 400:1 divider with the 50Ω resistor and
the oscilloscope. A test point is included for easy use of an oscilloscope probe.The compensation capacitor is used to
compensate the network to achieve flat frequency response.
3
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Typical Performance Characteristics (VCC = +180VDC, VBB = +8VDC, CL = 8pF, VOUT = 130VPP
(35V − 165V), Test Circuit - Figure 3 unless otherwise specified)
20073105
20073104
FIGURE 7. Speed vs Load Capacitance
FIGURE 4. VOUT vs VIN
20073106
20073108
FIGURE 5. LM2429 Pulse Response
FIGURE 8. Speed vs Offset
20073118
20073109
FIGURE 6. Bandwidth
FIGURE 9. Speed vs Case Temperature
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4
Typical Performance Characteristics (VCC = +180VDC, VBB = +8VDC, CL = 8pF, VOUT = 130VPP
(35V − 165V), Test Circuit - Figure 3 unless otherwise specified) (Continued)
20073107
FIGURE 10. Power Dissipation vs Frequency
20073116
FIGURE 11. Power Derating Curve
20073119
FIGURE 12. Cathode Pulse Response
5
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Typical Performance Characteristics (VCC = +180VDC, VBB = +8VDC, CL = 8pF, VOUT = 130VPP
(35V − 165V), Test Circuit - Figure 3 unless otherwise specified) (Continued)
TABLE 1. Power Dissipation for Various Video Patterns
Power Dissipation (W)
Pattern
Format
480i
480p
1.8
4.0
3.1
3.3
2.8
3.0
2.7
3.9
2.6
4.1
7.3
8.9
4.3
4.4
6.2
6.3
7.1
8.7
11.4
15.4
Raster
Full White Field
1.8
4.0
3.1
3.2
2.7
3.0
2.7
3.6
2.3
3.8
5.2
6.1
3.4
3.7
5.0
4.6
5.0
5.6
7.2
11.5
White Box, 75% Screen Size
Gray Bars
Color Bars 75% Amplitude
Color Bars 100% Amplitude
SMPTE Color Bars
SMPTE 133
Cross Hatch 16x12
Resolution Chart
Multiburst
White Text on Black Background
Windows Pattern
Windows Pattern
Windows Pattern
Vertical Lines 5 On 5 Off
Vertical Lines 4 On 4 Off
Vertical Lines 3 On 3 Off
Vertical Lines 2 On 2 Off
Vertical Lines 1 On 1 Off
<
f
Note: Input from signal generator: t , t
2 ns.
r
Theory of Operation
Application Hints
The LM2429 is a high voltage monolithic three channel CRT
driver suitable for HDTV applications. The LM2429 operates
with 180V and 8V power supplies. The part is housed in the
industry standard 11-lead TO-220 molded plastic power
package with thin leads for improved metal-to-metal spacing.
INTRODUCTION
National Semiconductor (NSC) is committed to provide ap-
plication information that assists our customers in obtaining
the best performance possible from our products. The fol-
lowing information is provided in order to support this com-
mitment. The reader should be aware that the optimization of
performance was done using a specific printed circuit board
designed at NSC. Variations in performance can be realized
due to physical changes in the printed circuit board and the
application. Therefore, the designer should know that com-
ponent value changes may be required in order to optimize
performance in a given application. The values shown in this
document can be used as a starting point for evaluation
purposes. When working with high bandwidth circuits, good
layout practices are also critical to achieving maximum per-
formance.
The circuit diagram of the LM2429 is shown in Figure 2. The
PNP emitter follower, Q5, provides input buffering. Q1 and
Q2 form a fixed gain cascode amplifier with resistors R1 and
R2 setting the gain at −51. Emitter followers Q3 and Q4
isolate the high output impedance of the cascode stage from
the capacitance of the CRT cathode which decreases the
sensitivity of the device to load capacitance. Q6 provides
biasing to the output emitter follower stage to reduce cross-
over distortion at low signal levels.
Figure 3 shows a typical test circuit for evaluation of the
LM2429. This circuit is designed to allow testing of the
LM2429 in a 50Ω environment without the use of an expen-
sive FET probe. In this test circuit, the two 4.99kΩ resistors
form a 400:1 wideband, low capacitance probe when con-
nected to a 50Ω coaxial cable and a 50Ω load (such as a
50Ω oscilloscope input). The input signal from the generator
is ac coupled to the base of Q5.
IMPORTANT INFORMATION
The LM2429 performance is targeted for the HDTV market.
The application circuits shown in this document to optimize
performance and to protect against damage from CRT ar-
cover are designed specifically for the LM2429. If another
member of the LM242X family is used, please refer to its
datasheet.
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6
EFFECT OF OFFSET
Application Hints (Continued)
Figure 8 shows the variation in rise and fall times when the
output offset of the device is varied from 95V to 105VDC. The
rise time shows a variation of less than 8% relative to the
center data point (100VDC). The fall time shows a variation of
less than 9% relative to the center data point.
POWER SUPPLY BYPASS
Since the LM2429 is a wide bandwidth amplifier, proper
power supply bypassing is critical for optimum performance.
Improper power supply bypassing can result in large over-
shoot, ringing or oscillation. 0.1µF capacitors should be con-
nected from the supply pins, VCC and VBB, to ground, as
close to the LM2429 as is practical. Additionally, a 22µF or
larger electrolytic capacitor should be connected from both
supply pins to ground reasonably close to the LM2429.
THERMAL CONSIDERATIONS
Figure 9 shows the performance of the LM2429 in the test
circuit shown in Figure 3 as a function of case temperature.
The figure shows that the rise and fall times of the LM2429
increase by approximately 15% and 30%, respectively, as
the case temperature increases from 50˚C to 90˚C. This
corresponds to a speed degradation of 3.75% and 7.5% for
every 10˚C rise in case temperature.
ARC PROTECTION
During normal CRT operation, internal arcing may occasion-
ally occur. Spark gaps, in the range of 300V, connected from
the CRT cathodes to CRT ground will limit the maximum
voltage, but to a value that is much higher than allowable on
the LM2429. This fast, high voltage, high energy pulse can
damage the LM2429 output stage. The application circuit
shown in Figure 13 is designed to help clamp the voltage at
the output of the LM2429 to a safe level. The clamp diodes,
D1 and D2, should have a fast transient response, high peak
current rating, low series impedance and low shunt capaci-
tance. 1SS83 or equivalent diodes are recommended. D1
and D2 should have short, low impedance connections to
VCC and ground respectively. The cathode of D1 should be
located very close to a separately decoupled bypass capaci-
tor (C3 in Figure 13). The ground connection of D2 and the
decoupling capacitor should be very close to the LM2429
ground. This will significantly reduce the high frequency
voltage transients that the LM2429 would be subjected to
during an arcover condition. Resistor R2 limits the arcover
current that is seen by the diodes while R1 limits the current
into the LM2429 as well as the voltage stress at the outputs
Figure 10 shows the power dissipation of the LM2429 vs.
Frequency when all three channels of the device are driving
an 8pF load with a 130VPP alternating one pixel on, one pixel
off signal. The graph assumes a 72% active time (device
operating at the specified frequency) which is typical in a TV
application. The other 28% of the time the device is assumed
to be sitting at the black level (165V in this case). Table 1
also shows the typical power dissipation of the LM2429 for
various video patterns in the 480i and 480p video formats.
Figure 10, Figure 11, and Table 1 give the designer the
information needed to determine the heatsink requirement
for the LM2429. For example, if an HDTV application uses
the 480p format and "Vertical Lines 2 On 2 Off" is assumed
to be the worst-case pattern to be displayed, then the power
dissipated will be 11.4W (from Table 1). Figure 11 shows that
the maximum allowed case temperature is 117˚C when
11.4W is dissipated. If the maximum expected ambient tem-
perature is 70˚C, then a maximum heatsink thermal resis-
tance can be calculated:
of the device. R2 should be a 1⁄
2W solid carbon type resistor.
1
R1 can be a ⁄
4W metal or carbon film type resistor. Having
large value resistors for R1 and R2 would be desirable, but
this has the effect of increasing rise and fall times. Inductor
L1 is critical to reduce the initial high frequency voltage
levels that the LM2429 would be subjected to. The inductor
will not only help protect the device but it will also help
minimize rise and fall times as well as minimize EMI. For
proper arc protection, it is important to not omit any of the arc
protection components shown in Figure 13.
This example assumes a capacitive load of 8pF and no
resistive load. The designer should note that if the load
capacitance is increased the AC component of the total
power dissipation will also increase.
Note: A LM126X preamplifier, with rise and fall times of about
2 ns, was used to drive the LM2429 for these power mea-
surements. Using a preamplifier with rise and fall times
slower than the LM126X will cause the LM2429 to dissipate
less power than shown in Table 1.
OPTIMIZING TRANSIENT RESPONSE
In Figure 13, there are three components (R1, R2 and L1)
that can be adjusted to optimize the transient response of
the application circuit. Increasing the values of R1 and R2
will slow the circuit down while decreasing overshoot. In-
creasing the value of L1 will speed up the circuit as well as
increase overshoot. It is very important to use inductors with
very high self-resonant frequencies, preferably above 300
MHz. Ferrite core inductors from J.W. Miller Magnetics (part
20073110
FIGURE 13. One Channel of the LM2429 with the
Recommended Application Circuit
#
78FR_ _k) were used for optimizing the performance of the
device in the NSC application board. The values shown in
Figure 14 and Figure 15 can be used as a good starting point
for the evaluation of the LM2429. Using a variable resistor
for R1 will simplify finding the value needed for optimum
performance in a given application. Once the optimum value
is determined, the variable resistor can be replaced with a
fixed value.
EFFECT OF LOAD CAPACITANCE
Figure 7 shows the effect of increased load capacitance on
the speed of the device. This demonstrates the importance
of knowing the load capacitance in the application.
7
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•
•
•
C19—VCC bypass capacitor, located very close to pin 2
and ground pins
Application Hints (Continued)
Figure 12 shows the typical cathode pulse response with an
C20—VBB bypass capacitor, located close to pin 11 and
ground
output swing of 130VPP using a LM1269 preamplifier.
C46, C48—VCC bypass capacitors, near LM2429 and
VCC clamp diodes. Very important for arc protection.
PC BOARD LAYOUT CONSIDERATIONS
For optimum performance, an adequate ground plane, iso-
lation between channels, good supply bypassing and mini-
mizing unwanted feedback are necessary. Also, the length of
the signal traces from the preamplifier to the LM2429 and
from the LM2429 to the CRT cathode should be as short as
possible. The following references are recommended:
The routing of the LM2429 outputs to the CRT is very critical
to achieving optimum performance. Figure 17 shows the
routing and component placement from pin 10 (V1OUT) of
the LM2429 to the blue cathode. Note that the components
are placed so that they almost line up from the output pin of
the LM2429 to the blue cathode pin of the CRT connector.
This is done to minimize the length of the video path be-
tween these two components. Note also that D8, D9, R24
and D6 are placed to minimize the size of the video nodes
that they are attached to. This minimizes parasitic capaci-
tance in the video path and also enhances the effectiveness
of the protection diodes. The anode of protection diode D8 is
connected directly to a section of the the ground plane that
has a short and direct path to the LM2429 ground pins. The
cathode of D9 is connected to VCC very close to decoupling
capacitor C48 which is connected to the same section of the
ground plane as D8. The diode placement and routing is
very important for minimizing the voltage stress on the
LM2429 during an arcover event. Lastly, notice that S3 is
placed very close to the blue cathode and is tied directly to
CRT ground.
Ott, Henry W., “Noise Reduction Techniques in Electronic
Systems”, John Wiley & Sons, New York, 1976.
“Video Amplifier Design for Computer Monitors”, National
Semiconductor Application Note 1013.
Pease, Robert A., “Troubleshooting Analog Circuits”,
Butterworth-Heinemann, 1991.
Because of its high small signal bandwidth, the part may
oscillate in a TV if feedback occurs around the video channel
through the chassis wiring. To prevent this, leads to the video
amplifier input circuit should be shielded, and input circuit
wiring should be spaced as far as possible from output circuit
wiring.
TYPICAL APPLICATION
A typical application of the LM2429 is shown in the sche-
matic for the NSC demonstration board in Figure 14 and
Figure 15. Used in conjunction with an LM126X preamplifier,
a complete video channel from input to CRT cathode can be
achieved. Performance is ideal for DTV applications. The
NSC demonstration board can be used to evaluate the
LM126X/LM2429 combination in a TV.
This demonstration board uses large PCB holes to accom-
modate socket pins, which function to allow for multiple
insertions of the LM2429 in a convenient manner. To benefit
from the enhanced LM2429 package with thin leads, the
device should be secured in small PCB holes to optimize the
metal-to-metal spacing between the leads.
NSC DEMONSTRATION BOARD
Figure 16 shows the routing and component placement on
the NSC LM126X/LM2429 demonstration board. This board
provides a good example of a layout that can be used as a
guide for future layouts. Note the location of the following
components:
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8
Application Hints (Continued)
20073111
FIGURE 14. LM126X/LM242X/LM248X Demonstration Board Schematic
9
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Application Hints (Continued)
20073112
FIGURE 15. LM126X/LM242X/LM248X Demonstration Board Schematic (continued)
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10
Application Hints (Continued)
20073113
FIGURE 16. LM126X/LM242X/LM248X Demonstration Board Layout
20073114
FIGURE 17. Trace Routing and Component Placement for Blue Channel Output
11
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Physical Dimensions inches (millimeters) unless otherwise noted
CONTROLLING DIMENSION IS INCH
VALUES IN [ ] ARE MILLIMETERS
NS Package Number TE11B
Order Number LM2429
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.
For the most current product information visit us at www.national.com.
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