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LM2437 Dataheets PDF



Part Number LM2437
Manufacturers National Semiconductor
Logo National Semiconductor
Description Monolithic Triple 7.5 ns CRT Driver
Datasheet LM2437 DatasheetLM2437 Datasheet (PDF)

LM2437 Monolithic Triple 7.5 ns CRT Driver August 1999 LM2437 Monolithic Triple 7.5 ns CRT Driver General Description The LM2437 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 −14 and can drive CRT capacitive loads as well as resistive loads present in other applications, limited only by th.

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LM2437 Monolithic Triple 7.5 ns CRT Driver August 1999 LM2437 Monolithic Triple 7.5 ns CRT Driver General Description The LM2437 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 −14 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 power package. See Thermal Considerations section. Features n Well matched with LM1279 video preamp n 0V to 4.5V input range n Stable with 0–20 pF capacitive loads and inductive peaking networks n Convenient TO-220 staggered lead package style n Standard LM243X Family Pinout which is designed for easy PCB layout Applications n 1024 x 768 displays up to 85 Hz refresh n Pixel clock frequencies up to 100 MHz n Monitors using video blanking Schematic and Connection Diagrams DS100932-2 Note: Tab is at GND Top View Order Number LM2437T DS100932-1 FIGURE 1. Simplified Schematic Diagram (One Channel) © 1999 National Semiconductor Corporation DS100932 www.national.com 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) +90V +16V 0V to 6V −65˚C to +150˚C Lead Temperature (Soldering, < 10 sec.) ESD Tolerance, Human Body Model Machine Model 300˚C 2 kV 250V Operating Ranges (Note 2) VCC +60V to +85V +8V to +15V VBB +0V to +5V VIN +15V to +75V VOUT Case Temperature −20˚C to +100˚C Do not operate the part without a heat sink. Electrical Characteristics (See Figure 2 for Test Circuit) Unless otherwise noted: VCC = +80V, VBB = +12V, VIN = +2.7 VDC, CL = 8 pF, Output = 40 VPP at 1 MHz, TC = 50˚C. Symbol ICC IBB VOUT AV ∆AV LE tR tF OS Parameter Supply Current Bias Current DC Output Voltage DC Voltage Gain Gain Matching Linearity Error Rise Time Fall Time Overshoot Conditions All Three Channels, No Input Signal, No Output Load All Three Channels No AC Input Signal, VIN = 1.2V No AC Input Signal (Note 4), No AC Input Signal (Notes 4, 5), No AC Input Signal (Note 6), 10% to 90% (Note 6), 90% to 10% (Note 6) 62 −12 LM2437 Min Typical 34.5 11 65 −14 1.0 8 7.5 7.5 5 68 −16 dB % ns ns % Max 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 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 = 1.0V to VIN = 4.5V. Note 6: Input from signal generator: tr, tf < 1 ns. AC Test Circuit DS100932-3 Note: 8 pF load includes parasitic capacitance. FIGURE 2. Test Circuit (One Channel) Figure 2 shows a typical test circuit for evaluation of the LM2437. This circuit is designed to allow testing of the LM2437 in a 50Ω environment without the use of an expensive FET probe. The two 2490Ω resistors form a 200:1 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 stray capacitance of the two 2490Ω resistors to achieve flat frequency response. www.national.com 2 Typical Performance Characteristics (VCC = +80 VDC, VBB = +12 VDC, CL = 8 pF, VOUT = 40 VPP (25V−65V), Test Circuit - Figure 2 unless otherwise specified) DS100932-4 FIGURE 3. VOUT vs VIN DS100932-7 FIGURE 6. Power Dissipation vs Frequency DS100932-5 FIGURE 4. Speed vs Temp. DS100932-8 FIGURE 7. Speed vs Offset DS100932-6 FIGURE 5. LM2437 Pulse Response DS100932-9 FIGURE 8. Speed vs Load Capacitance 3 www.national.com Theory of Operation The LM2437 is a high voltage monolithic three channel CRT driver suitable for high resolution display applications. The LM2437 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 LM2437 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 −14. Emitter followers Q3 and Q4 isolate the high output impedance of the cascode stage from the capacitance of the CRT ca.


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