LM2453
Monolithic Triple 6 nS CRT Driver With Integrated Clamp
and G1 Blanking
General Description
The AC2DC driver is an integrated high voltage triple CRT
driver circuit designed for use in color monitor applications.
The input signal interface to the IC is a multiplexed signal
containing both clamp and video signal information, relative
to a 1.7 V
DC
reference.
The IC contains three high gain, high input impedance, wide
band amplifiers which directly drive the RGB cathodes of a
CRT. Each channel has its gain internally set to -52 and can
drive CRT capacitive loads as well as resistive loads present
in other applications, limited only by the package's power
dissipation.
Integrated with the driver is triple clamp circuit for DC recov-
ery of each of the AC coupled outputs. The DC clamp circuit
amplifies the clamp signal that is multiplexed on the video
signal input. The DC clamp amplifiers are high gain, high in-
put impedance amplifiers, setting a low impedance DC level
at the clamp output which can be used to restore the DC
level of the cathode drive. Each channel has a gain that is in-
ternally set to +73.
Also integrated within the package is a 40 V
P-P
vertical
blanking driver that is designed to provide vertical retrace
blanking on G1 of the CRT. This is a current limited, low im-
pedance output capable of driving normal G1 decoupling ca-
pacitances via an external resistor. The output of the G1
driver can also be used to drive a voltage boost capacitor (22
F). When connected between the G1 drive output and the
120V supply input pin, a 120V boost supply is achieved
which can be used to drive the internal DC clamp circuit,
thereby eliminating the requirement for a 120V clamp supply.
The IC is packaged in an industry standard 15-lead TO-220
molded plastic power package.
Features
n
Low power dissipation
n
Well matched with LM1253A video pre-amp
n
Three wideband video amplifiers
n
Three integrated active clamp circuits
n
Convenient TO-220 staggered lead package
n
Built in horizontal blanking
n
Integrated 120V supply and G1 vertical blank drive
circuit
Applications
n
1280 x 1024 Resolution displays up to 85 Hz refresh
n
Pixel clock frequencies up to 135 MHz
n
Monitors requiring horizontal video blanking
Block Diagram
Package Pinout
DS101302-1
FIGURE 1. LM2453 Block Diagram
DS101302-2
FIGURE 2. LM2453 Package Pinout
Order Number LM2453TA
April 2000
LM2453
Monolithic
T
riple
6
n
S
CRT
Driver
W
ith
Integrated
Clamp
and
G1
Blanking
2000 National Semiconductor Corporation
DS101302
www.national.com
Special Features
MULTIPLEXED VIDEO SIGNAL INPUT
The LM2453 accepts the multiplexed video signal from the
LM1253 which contains the video signal and DC clamp level.
This multiplexed signal is shown in
Figure 3. It was designed
to simplify the interface between the pre-amp and CRT
Driver. Slightly over 1V of dynamic range is provided for the
video and OSD portions of the waveform. The clamp signal
control voltage range is approximately 0.9V. The typical
numbers for the black and white levels shown correspond to
a nominal swing of 40 V
P-P
(from 25 to 65) at the video out-
puts of the LM2453. The clamp pulse lower level is used to
set the voltage at the clamp outputs of the LM2453.
DS101302-3
FIGURE 3. National LM1253 Multiplexed Video Signal
LM2453
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2
Absolute Maximum Ratings
(Notes 1, 3)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
80V Voltage, V
CC1
+90V
120V Supply V
CC2
+130V
Bias Voltage, V
BB
+15V
Input Voltage, V
IN
0V to 4V
V
BLANK
Input Voltage, V
BLANK
0V to V
BB
V
Storage Temperature Range, T
STG
-65C to +150C
Lead Temperature
(Soldering,
<
10 sec.)
300C
ESD Tolerance, Human Body
Model
2 kV
ESD Tolerance, Machine Model
200V
Operating Ranges
(Note 2)
V
CC1
+60V to +85V
V
BOOST
V
CC1
to +125V
V
BB
7.0V to +9V
V
IN
0.8V to +3.5V
V
REF
+1.6V to +1.9V
V
BLANK
Input Voltage, V
BLANK
0V to 5.5V
V
OUT
+15V to +78V
V
CLAMP
+55V to +118V
Case Temperature
-20C to 100C
AC Driver Electrical Characteristics
(See
Figure 4 for Test Circuit)
Unless otherwise noted: V
CC
= +80V, V
BB
= +8V, V
IN
= 2.500 V
DC
, C
L
= 8 pF, Output = 40 V
PP
at 1 MHz, T
C
= 50C,
V
REF
= 1.735V, HEATSINK MUST BE GROUNDED.
Symbol
Parameter
Conditions
Min
Typ
Max
Units
I
CC
V
CC
Supply Current
All 3 Channels, No Output Load
35
45
mA
I
BB
V
BB
Supply Current
All 3 Channels, No Output Load
22
35
mA
I
OUTTYP
Typical DC Output Voltage
No AC Input Signal, V
IN
= 2.100 V
DC
62
66
70
V
DC
A
VTYP
Typical DC Voltage Gain
No AC Input Signal
-52
V/V
I
RTYP
Typical Rise Time
10% to 90%, (Note 5)
6.0
ns
+OS
Overshoot on Rising Edge
5
%
t
FTYP
Typical Fall Time
90% to 10%, (Note 5)
6.0
ns
-OS
Overshoot on Falling Edge
6
%
LE
Linearity Error
V
IN
2.0 V
DC
to 3.0 V
DC
, (Note 4)
6
%
Note 1: Limits of "Absolute Maximum Ratings" indicate limits below which damage to the device will not occur.
Note 2: Limits of "Operating Ratings" indicate required boundaries of conditions for which the device is functional, but is not guaranteed to meet specific performance
limits.
Note 3: All voltages are measured with respect to GND, unless otherwise specified.
Note 4: Linearity error is the variation in DC gain from V
IN
= 2.0 to 3.0.
Note 5: Input from signal generator: t
r
, t
f
<
1 ns.
DRIVER Test Circuit
Figure 4 shows the test circuit for the LM2453. This circuit allows testing of the LM2453 in a 50
environment as well as with a
FET probe. The 4950
resistor at the output forms a 200:1 voltage divider when connected to a 50
load. C
COMP
must be ad-
justed for equivalent performance to the FET probe. Performance will be affected slightly by the 5k load.
DS101302-4
FIGURE 4. Test Circuit (One Channel)
LM2453
www.national.com
3
DRIVER Test Circuit
(Continued)
DS101302-5
FIGURE 5. CRT Driver V
O
vs V
IN
DS101302-6
FIGURE 6. CRT Driver Speed vs. Temperature
DS101302-7
FIGURE 7. CRT Driver Transient Response
DS101302-8
FIGURE 8. CRT Driver Power
Dissipation vs. Frequency
DS101302-9
FIGURE 9. CRT Driver Speed vs. Offset
DS101302-10
FIGURE 10. Speed vs. Load
LM2453
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4
DC CLAMP Electrical Characteristic Targets and Limits
(See
Figure 11 for Test Circuit)
Unless otherwise noted: V
CC1
= +80V, V
CC2
= 120V, V
BB
= +8V, T
C
= 50C, V
REF
= 1.735V, SW1 open.
HEATSINK MUST BE GROUNDED.
Symbol
Parameter
Conditions
Min
Typ
Max
Units
I
CC2
V
CC2
Supply Current
All 3 Channels V
IN
= 1.20 V
DC
4
7
mA
V
OUT
DC Output Voltage
No AC Input Signal, V
IN
= 1.400V
87
92
97
V
DC
A
VTYP
Typical DC Voltage Gain
No AC Input Signal
73
LE
TYP
Typical Linearity Error
No AC Input Signal (Note 6)
2
%
Note 6: Linearity Error is the variation in DC gain from V
IN
= 1.0V to V
IN
= 1.6V.
Clamp Amplifier Test Circuit
Figure 7 shows the test circuit for evaluation of the LM2453 clamp amplifier. A high impedance VM (
>
100 M
) is used for DC
measurements at the outputs.
DS101302-11
FIGURE 11. Test Circuit (One Channel)
DS101302-12
FIGURE 12. Clamp Circuit V
O
vs. V
IN
LM2453
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5
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