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LM2469 Monolothic Triple 9nS High Gain CRT Driver
October 2000
LM2469 Monolothic Triple 9nS High Gain CRT Driver
General Description
The LM2469 is an integrated high voltage CRT driver circuit designed for use in color monitor 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 -20 and can drive CRT capacitive loads as well as resistive loads present in other applications, limited only by the package’s power dissipation. The IC is packaged in an industry standard 9 lead TO-220 molded plastic package. n 0V to 3.75V input range n Stable with 0-20pF capacitive loads and inductive peaking networks n Maintains standard LM243X Family Pinout which is designed for easy PCB layout n Convenient TO-220 staggered 9 lead package style
Applications
n Up to 1024 X 768 at 70Hz n Pixel clock frequencies up to 75MHz n Monitors using video blanking
Features
n Higher gain to match LM126X CMOS preamplifiers
Schematic Diagram
Connection Diagram
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Note: Tab is at GND.
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FIGURE 1. Simplified Schematic Diagram (One Channel)
FIGURE 2. Top View Order Number: LM2469TA NS package Number: TA09A
© 2000 National Semiconductor Corporation
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LM2469
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. Supply Voltage, VCC Bias Voltage, VBB Input Voltage, VIN Storage Temperature Range, TSTG Lead Temperature (Soldering, < 10sec.) ESD Tolerance, Human Body Model +90V +16V 0V to 4.5V -65˚C to +150˚C 300˚C 2kV
Limits of Operating Ranges
VCC VBB VIN VOUT
(Note 2)
+60V to +85V +8V to 15V 0V to +3.75V +15V to +75V
Case Temperature -20˚C to +100˚C Do not operate the part without a heat sink.
Electrical Characteristics
(See Figure 3 for Test Circuit) Unless otherwise noted: VCC = +80V, VBB = +12V, CL = 8pF, TC = 50˚C. DC Tests: VIN = +2.25VDC AC Tests: Output = 40VPP (25V - 65V) at 1MHz Symbol ICC IBB VOUT AV ∆AV LE tR tF OS Spec Parameter Supply Current Bias Current DC Output Voltage DC Voltage Gain Gain Matching Linearity Error Rise Time Fall Time Overshoot Conditions Per Channel, No Input Signal, No Output Load All three Channels No AC Input Signal, VIN = 1.25V No AC Input Signal Note 4, No AC Input Signal Note 4, 5, No AC Input Signal Note 6, 10% to 90% Note 6, 90% to 10% Note 6 62 -18 Min Typ 8 15 65 -20 1.0 5 9.5 10.5 5 Max 12 25 68 -22 dB % nS nS % Units mA mA VDC
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 the test conditions, see the Electrical Characteristics. 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 Vin = 1.0 volts to Vin = 3.5 volts. Note 6: Input from signal generator: tR, tF
< 1nS.
AC Test Circuit
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FIGURE 3. Test Circuit (One Channel)
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LM2469
Typical Performance Characteristics
(VCC = +80VDC, VBB = +12VDC, CL = +8pF, VOUT = 40VPP (25-65V), Test Circuit - Figure 3 unless otherwise specified.
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Figure 9: Vout vs Vin
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Figure 10: Power Dissipation vs Frequency
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Figure 11: Speed vs Temperature
Figure 12: Speed vs Offset
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Figure 13: LM2469 Pulse Response
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Figure 14: Speed vs Load Capacitance
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LM2469
THEORY OF OPERATION
The LM2469 is a high voltage monolithic three channel CRT driver suitable for color monitor applications. The LM2469 operates with 80V and 12V power supplies. The part is housed in the industry standard 9-lead TO-220 molded plastic power package. The circuit diagram of the LM2469 is shown in Figure 1. 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 -20. Emitter followers Q3 and Q4 isolate the high output impedance of the amplifier from the capacitive load on the output of the amplifier, decreasing the sensitivity of the device to changes in load capacitance. Q6 provides biasing to the output emitter follower stage to reduce crossover distortion at low signal levels. Figure 3 shows a typical test circuit for evaluation of the LM2469. This circuit is designed to allow testing of the LM2469 in a 50Ω environment without the use of an expensive FET probe. In this test circuit, two low inductance resistors in series totalling 4.95KΩ form.