LH2422 NSC | Alldatasheet
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N nx Po . = CA National PRELIMINARY Semiconductor CRT Video Driver Amplifier General Description Features The LH2422 CRT Video Driver is a wide bandwidth, large @ 110 MHz bandwidth at 40V swings signal amplifier designed to swing large voltages of short @ Rise/fall times of 3.3 ns duration. It works on a transimpedance principle, in that ™ Drives 8.5 pF capacitive load about +6.5 mA input current results in an output voltage Of ~—™ Pin compatible with CR2424 +20V. The primary application for this very fast slewing am- gs pcg led f it level adjust plier is for driving High Resolution Monochrome or Color & Output 3 oe outa sO graphics monitors. These drivers can easily energize a ‘0 ng 10 ns pixel. This makes the LH2422 very attractive for 1024 x 1024 displays. The LH2422 is DC coupled and can APPlications ; interface to National’s LM1201 and LM1203 Preamplifiers, | ™ CRT driver for color and monochrome monitors ® High voltage transimpedance amplifier Schematic and Connection Diagrams ‘9 OUTPUT
8 GROUND
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3 GROUND
WAT Z {INVERTING INPUT i 2,3,7.8 Lo |
6 TUK/10128-2
GROUND Order Number LH2422J TUK10128-1 See NS Package Number HY09A | 3-8
Absolute Maximum Ratings iS If Military/Aerospace specified devices are required, Storage Temperature Range, TSTG 40°C to + 125°C 8 please contact the National Semiconductor Sales Operating Temperature Range, Tcase —20°C to +80°C Office/Distributors for availability and specifications. Lead Temperature (Soldering, < 10 sec) 300°C Supply Voltage, Voc +70V ESD Tolerance Ted Power Dissipation, Pg 7wW Electrical Characteristics vcc = +s0v, Ri = 2150, C1 = 60 PF, CLoap = 8.5 pF, 40 Vp-p swing with 30 Vpc offset. See Figure 1. Tcasc = 25°C unless otherwise noted (Note 1). Symbol Conditions Tested | Design Unless Typical | Limit Limit | Otherwise (Note 2) | (Note 3) Noted) loc Supply Current No Input or Output Load [475 | 60 | ma Vinoc | input Offset Voltage No Input or Output Load [ 7 [|_| v [oats fT venti Vouroc | Output Oftset Voltage ee [26 fT vieniny Po SomHzsquerewave | 53 | 6 [| ow | risetime | towtooox | aa | t 20% to 10% ee Vrur__| LowFrequencyTitVottage | ikHzSquarewave | 13 | | S| Bw__| Bandwiath [mses 000 at ti Vos Owmmet | VG Insertion Gain 500 Source Z 14.5 wv 11.5, V/V (Min) Vourtom+sviorsv [ 1 [os [se | % Note 1: Boldface limits are guaranteed over full temperature range. Note 2: Tested limits are guaranteed and 100% Production tested. Note 3: Design limits are guaranteed (but ‘ot production tested) over the indicated temperature range. These limits are not used to calculate outgoing quality level, i
= Typical Performance Characteristics Voitage Ratio at Output Voltage RF Input Port Voltage Ratio at Pin 1 vs Input Current u TLLLLL wh LL a ‘ | a a | wf} fr tt eUN TPT) seerr 4 fee ¥ NSN gS) gg SE NEE iS ee B. NS i 2 148 7 i a |
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° rt S| Se a ne A w~LtLETEN i SEEEEES 0 2 BW 40 3 o n “” 6 o » 0 o DC OUTPUT VOLTAGE (V) DC OUTPUT VOLTAGE (V) DC OUTPUT VOLTAGE (V) Power Dissipation Frequency Response vs Frequency 0 pommee wes TES =, Seed OD PUTTTELEEBAEL EEL] «© Baal awe! heen SeLLTEETTTEIN TTT) Essent [Le 8 -150 IN 55 ra | seein «= E =| ee “200 ‘ 5 SLi wsmet A SCN #4 no LOTT Rs Pas agen se LOTTA weer TTT | ve LOTT TTT oo a L} K o wo 10 wpnnn no DOW FREQUENCY (MHz) FREQUENCY (MHz) TUK/10128-3 Application Hints OUTPUT INFORMATION the job. Cables of 752 and 932 or 3002 twin-lead, termi- The LH2422 is designed as a power amp for driving a Cath- nated by capacitance, will exhibit inductance. A damping ode Ray Tube (CRT). It can provide a 40V output swing and resistor should be used here. energize a 10 ns pixel. A CRT generally has a capacitance SHORT CIRCUIT PROTECTION 0f 8.5 pF. ; ‘The LH2422 does not have output short circuit protection. It Since a wire of some length is usually needed between is racommended that an output series resistance of at least tthe wor end are oe, eco grout is oe bloe 6000 be used for protection to ground or V+. 1@ wire’s inductance a 's capacitance. Objec- tionable ringing and overshoot can be evoided by using a INPUT INFORMATION damping resistor in series with the output and load. This The “Output Voltage vs Input Current” graph shows that a resistance can be calculated by using: +20V swing (from a 30V output DC bias) can be achieved R=20/76 with an input current swing of only +6.5 mA. The “Voltage " i "1 Ratio at RF Input Port” graph relates the input voltage as The output resistor is also recommended for protection m red at RF input port to the voltage at the output: note against tube arcing. Typical resistor values are 502 to easu - i : 1002. Sometimes the lead inductance may be artificially in- that the amplifier is phase-inverting. A 13.5 ratio is achieved. creased to obtain peaking if desired. Typically 0.2 H will do The above values are used to calculate a low frequency " vee input impedance of 2302 at the RF input port. 3-10
23 TT” PF
FIGURE 1. Typical AC Test Circult (pin 1) to the output with a ratio of 240. The calculated low- when driven from a 502 source. because of the internal 3 kM. feedback resistor shown in the the heat sink should be less than (80-50)"C/ SW = 6°C/W. +20V swing at the output. and 3 show the two approaches for proper heat sinking. erator’s DC level should be about 1.55V. Use a FET probe or V4.
FIGURE 2. Heat Sinking with an Aluminum Block
10 uF 2000, +12V9 S Video In OipeY brightness = 750. 0.1 wr 512. Control = 100 tT 0.001 uF TL | Male gS 10K i = = _[oor a i = o+i2 => nod: 8 S01 oT LL <|= 0.1 pF ; on 1 15 14 13 12. 4% 10 9 Composite (I, LE as Syne wees — 10k LM1201 u 0.1 uF PRE AMPLIFIER 750 (sync 0.1 uF ( » =vods SEPARATOR) ‘ 1 2 3 4 5 6 7 8B 680k on 4 5 t|—" feu 10k i +V +60V | 1000 = ' 0.01 pF 10 uF} 4700. i = 510 ct 2 5 = | 2NS770 = 4k Ld! 2 | 500 1600, a8 i 5600 KG b 500 C1,C2=10~ 100 pF | OF Diodes are 1N914 or equivalent i re ev = | = + BW = 100 Miz = J \\ eh 34 ii ‘ "s ‘TL/K/10128-7, | FIGURE 4. CRT Monitor Application \\ Evaluation Board 2. Use a 6 dB pad between the cable and the input. This will ' The evaluation board is intended to demonstrate the capa- reduce reflections and provide a 502 source to the circuit | bilities of the LH2422 CRT Driver Amplifier. The board may board. be used to interface the driver to a CRT display or evaluate i the frequency response or pulse response in a 502. system. ve Figure 5 shows the schematic of the LH2422 evaluation Q C2 board. k R1 sets the overall gain of the fixture. The test circuit used A 5 8 2200 to provide a gain of 12.5. C1 sets the “midband” ? | off peaking in the 30 MHz to 60 MHz range. A typical value for ry this capacitor is 40 pF. RI ct 23.7.8 Spo A large bypass capacitor, C2, is needed to reduce lower © K} frequency ringing caused by the power supply wires. V tS The input is designed to be fed from a 502 generator, how- © c wr ever, the input impedance at Vy is not well matched to 500. Vin 500 Scope and if a long cable is used between the generator and the TUK/10128-8 input, reflections will occur giving unpredictable responses. FIGURE 5. Schematic of LH2422 Evaluation Circuit Two things can be done to get around this problem: 1. Use a very short connector (less than 2 inches) between the generator and the input. 3-13
it to the specified value of 8.5 pF. FIGURE 6. PC Board Layout and Component Placement Guide