Triple 85MHz CRT Driver ca C CORPORATION CVA2425 FEATURES @ Bandwidth ........ 2.0. e certs 85MHZ @ Rise/Fall Time. ... 22.60. e eet eee eee <4,.0ns @ SWING . 6. eee ere tet e terete 40 Vp-p @ Supply Voltage... 06... eee eter eens 80Vv @ Pin to Pin Compatible with CVA2426, LH2626 and CR5527 DESCRIPTION The CVA2425 contains three video driver amplifiers designed specially to drive high resolution color monitors. With such tise and fall time and bandwidth, this device will provide excellent drive capability for the 1280 x 1024 and 1024 x 768 color monitors. ORDERING INFORMATION APPLICATIONS CRT D ' 0 and c Part Package Temperature e river for 1280 x 1024 and 1024 x 768 Color Monitors CVA24258 CY12B -20C to +100C CONNECTION DIAGRAM AND SIMPLIFIED SCHEMATIC Veco / Oo Oo \N ce ernneneee eee POR | i | > Vn oF B10 1/3 eenrnerogeogomma a + Z Ek + + Zae > = 9 2 > 2 9 5 > = 22 go 0 6 0 o GVA2425 GND 3,7,11 MH 1844322 O0011b) O3T 3-42 CORPORATION a ABSOLUTE MAXIMUM RATINGS CVA2425 Supply Voltage... 0... eee cee cece ee B5V Operating Temperature ................ -20C to +100C Storage Temperature..............02.. -25C to +100C Lead Temperature .........0...0.00 0000000008 +300C DC ELECTRICAL CHARACTERISTICS Vs = 80V, CL = 10pF, Vout = 40Vp-p, Tcase = +25C. See Figure 1. SYMBOL CHARACTERISTICS MIN TYP MAX UNITS loc Supply Current 24 30 mA Vinoc Input DC Level 1.4 1.6 1.8 Vv VoulbC Output DC Level 34 40 46 Av Voltage Gain 11 13 15 Vv Gain Matching 0.2 dB AC ELECTRICAL CHARACTERISTICS Vg = 80V, C_ = 10pF, Vout = 40Vp-p, Toase = +25C. See Figure 1. SYMBOL CHARACTERISTICS MIN TYP MAX UNITS t Rise Time 3.8 5.0 ns tf Fall Time 3.6 5.0 ns BW Bandwidth 35 MHz Le Linearity 5 % os Overshoot 10 % FIGURE 1. APPLICATION AND TEST CIRCUIT Vee C c2 a R2 INPUT WA OUTPUT Low Cy C1 Ry R1=10Q R6 = 222 C1 = Variable 4 to 150pF C4 = 10pf/160V D1 =DS464 R2 = 4302 R7 =6.8kQ Typical 43pF C_ = 10pF (Including D2 = DS464 R4 = 100k 2 +5%, 2 Watt C2 = Variable 4 to 150pF Parasitic} L1 = 560nH RS = 220 Typical 22pF C6 = 0.01 nt 60V C3 = 68pF MB 1844322 OOOllbe Teh 3-43 CVA2425 APPLICATIONS INFORMATION Basic Circuit Configuration The CVA2425 is an transimpedance amplifier with two stage feedback amplifier configurations. Any change in input current will be reflected as change in output voltage swing. A resistor in series with the input will change the CVA2425 into a voltage amplifier. The output is an emitter follower. Because of the complementary circuitry employed, there is no need for toad or pull up resistor. An internally bypassed capacitor ts included inside the package, however, for low frequencies an electrolytic capacitor is recommended. CVA2425 has an internal feedback resistor of 5.7KQ. In the absence of any input signal, the Vout DC is set by R Vout (DC) = (1 +55) Vin (DC) If an input signal is applied, the gain is set by R Vout = RD Vin Input and Transfer Characteristics An input current swing of +4.5mA causes the output to change by +25V. A resistor of 430Q in series with the input will give a voltage gain of -13. Input pins are internal de feedback nodes and thus have low impedances. These pins must be fed from a series RC network for high frequency emphasis. Figure 2 shows several appropriate networks for design aides. CORPORATION a Output Characteristics CVA2425 is intended to be used as the final stage of very fast video circuits. The nominal load capacitance is 10pF. Other values can be accommodated since the output stage is an emitter follower and is fairly insensitive to load capacitance. However, a wire connection of some length is unavoidable, that causes objectionable ringing due to a resonant circuit. To avoid this a damping resistor must be used in series with the lead inductance. Also a resistor is necessary to protect the amplifier against arching. A resistor of 50-1000 will provide protection but will slow down the response. The lead inductance may be attificially increased by a tenth of a microHenry to obtain desired peak. Any change in inductance will require readjustment of damping resistor, as stated by equation (1). R=VE (1) The output of CVA2425 is not short circuit proof. Any resistance to V+ or Ground should be >600Q. Thermal Characteristics When low frequency square waves are amplified, some droop will occur due to a large change in thermal dissipation in the input transistors. To overcome this an R-C series feedback network is suggested with 100kQ and 56pf values. Under normal operating conditions the CVA2425 will dissipate up to 40W. The maximum allowed case temperature is +100C. To calculate maximum heatsink thermal resistance use equation (2). Pith = C0020 - 5.0CW The Thermalloy #11699 is one example of a heatsink that meets this requirement. FIGURE 2. Vout b Nea , 65V OUTPUT VOLTAGE (VOLTS) 45V \ i i | | 5 fo 6 15 20 HO TIME (ns) - 430Q OO a) ~22pF o-4 4300 ) 7430 s00 100 ~43pF 4300 a) ~22pF ME 1844322 0001163 0c calogic CVA2425 RISE & FALL TIME @ 40V,., RISE & FALL TIME @ 50V,., a o 4 Z 36h __ a g Pa? Q an = aH 35 oO = 3f q Zz = 3 oS 25 4. : 25 60 70 80 90 =69VOLTS 70 80 90 )=6 VOLTS Voc Veo RISE TIME @ RISE TIME FALL TIME FALL TIME RISE TIME FALL TIME BANDWIDTH ae oe zz a Qo = a> = {> o> oF oO $8 $8 3 5ns/DIV 5ns/DIV MHz MH 1844322 OOOLL6EY 849 3-45 CVA2425 cal CORPORATION FIGURE 4. RGB CRT VIDEO CIRCUIT USING CVA2425 AND CVA1203 2000 100a TL 22pF CVA2425 4302. me 48pF 1002 mee 2002 3902 VF 512 1002 22pF 2000 100 100k2 20Q by = 560nH 402 43pF BkQ 4302 | uF 512 St t 2 a7 5 4 3 26 a 1OuF 0 1pF 4 25 vineo 752 yorn =O THF So 4 5 24 Ha 6 Our 6 23 LH DE video 752 40Ke2 sia GS 7 22 CVA1203 sil} a1 8 10ND O1pF } 9 20 44 wipro 752 10kQ 5a 10 19 F+4 0 1pF , " 18 + 10pF 42 17 1 13 16 0 O1pF MAX 14 15 CONTRAST ~~ CONTROL | MIN ~~ 0 1pF Oks 40kQ| BLACK LEVEL (BRIGHTNESS) 10k2) CONTROL BLACK LEVEL 0 1nF GATE IN 390 { 402 100kQ. 43pF 8 BpF 220 22Q Lb, =560nH 12 Ry R, Your B The 390 resistors connected to pins 2, 6, 10 will shift (Voc out) DC to GOV. RF Vbc out= (1+ Re // 390) Vin oe 5700 _ ie. = (1 +360 1/390 ii 350) 1.6 =61.6V Me 1844322 0001165 765 The RC Network between pin 2, 6, 10 and pin 4, 8, 12 is the mark Compensation Network. The two 22Q resistors at the output will slow the response. Adding inductor L, will restore the response and provide additional protection from tube arcing.