NSC LM2453TA Datasheet

April 2000

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

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 recovery 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 input 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 internally set to +73.

Also integrated within the package is a 40 V blanking driver that is designed to provide vertical retrace blanking on G1 of the CRT. This is a current limited, low impedance output capable of driving normal G1 decoupling ca-

reference.

P-P

vertical

pacitances via an external resistor. The output of the G1 driver can also be used to drive a voltage boost capacitor (22 µF). 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

Special Features

LM2453

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 to simplify the interface between the pre-amp and CRT

Figure 3

. It was designed

FIGURE 3. National LM1253 Multiplexed Video Signal

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

(from 25 to 65) at the video out-

P-P

puts of the LM2453. The clamp pulse lower level is used to set the voltage at the clamp outputs of the LM2453.

DS101302-3

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LM2453

Absolute Maximum Ratings (Notes 1, 3)

ESD Tolerance, Machine Model 200V

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.

80V Voltage, V 120V Supply V Bias Voltage, V Input Voltage, V V

BLANK

CC1 CC2

Input Voltage, V

BLANK

Storage Temperature Range, T

STG

−65˚C to +150˚C

+90V

+130V

+15V

0V to 4V

0V to VBBV

Lead Temperature

(Soldering,

10 sec.) 300˚C

ESD Tolerance, Human Body

Model 2 kV

Operating Ranges (Note 2)

CC1

BOOST

REF

Input Voltage, V V V

BLANK OUT CLAMP

BLANK

Case Temperature −20˚C to 100˚C

+60V to +85V

to +125V

CC1

7.0V to +9V

0.8V to +3.5V

+1.6V to +1.9V

0V to 5.5V

+15V to +78V

+55V to +118V

AC Driver Electrical Characteristics

(See

Figure 4

Unless otherwise noted: VCC= +80V, VBB= +8V, VIN= 2.500 VDC,CL= 8 pF, Output = 40 VPPat 1 MHz, TC= 50˚C, V

= 1.735V, HEATSINK MUST BE GROUNDED.

REF

Symbol Parameter Conditions Min Typ Max Units

OUTTYP

VTYP

RTYP

+OS Overshoot on Rising Edge 5 % t

FTYP

−OS Overshoot on Falling Edge 6 % LE Linearity Error V

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 Note 5: Input from signal generator: t

for Test Circuit)

VCCSupply Current All 3 Channels, No Output Load 35 45 mA VBBSupply Current All 3 Channels, No Output Load 22 35 mA Typical DC Output Voltage No AC Input Signal, VIN= 2.100 V

62 66 70 V

Typical DC Voltage Gain No AC Input Signal −52 V/V Typical Rise Time 10% to 90%, (Note 5) 6.0 ns

Typical Fall Time 90% to 10%, (Note 5) 6.0 ns

2.0 VDCto 3.0 VDC, (Note 4) 6 %

= 2.0 to 3.0.

r,tf

1 ns.

DRIVER Test Circuit

FIGURE 4. Test Circuit (One Channel)

Figure 4

FET probe. The 4950Ω resistor at the output forms a 200:1 voltage divider when connected to a 50Ω load. C justed for equivalent performance to the FET probe. Performance will be affected slightly by the 5k load.

shows the test circuit for the LM2453. This circuit allows testing of the LM2453 in a 50Ω environment as well as with a

COMP

DS101302-4

must be ad-

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DRIVER Test Circuit (Continued)

LM2453

FIGURE 5. CRT Driver VOvs V

DS101302-5

DS101302-8

FIGURE 8. CRT Driver Power

Dissipation vs. Frequency

DS101302-6

FIGURE 6. CRT Driver Speed vs. Temperature

DS101302-7

FIGURE 7. CRT Driver Transient Response

DS101302-9

FIGURE 9. CRT Driver Speed vs. Offset

DS101302-10

FIGURE 10. Speed vs. Load

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LM2453

DC CLAMP Electrical Characteristic Targets and Limits (See

Unless otherwise noted: V

CC1

= +80V, V

= 120V, VBB= +8V, TC= 50˚C, V

CC2

= 1.735V, SW1 open.

REF

Figure 11

for Test Circuit)

HEATSINK MUST BE GROUNDED.

Symbol Parameter Conditions Min Typ Max Units

CC2

OUT

VTYP

TYP

Note 6: Linearity Error is the variation in DC gain from VIN= 1.0V to VIN= 1.6V.

Supply Current All 3 Channels VIN= 1.20 V

CC2

47mA DC Output Voltage No AC Input Signal, VIN= 1.400V 87 92 97 V Typical DC Voltage Gain No AC Input Signal 73 Typical Linearity Error No AC Input Signal (Note 6) 2 %

Clamp Amplifier Test Circuit

Figure 7

shows the test circuit for evaluation of the LM2453 clamp amplifier. A high impedance VM (>100 MΩ) is used for DC

measurements at the outputs.

FIGURE 11. Test Circuit (One Channel)

DS101302-12

FIGURE 12. Clamp Circuit VOvs. V

DS101302-11

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