Low Cost Triple CRT Driver CORPORATION CVA2405T FEATURES DESCRIPTION • • • • • The CVA2405T contains three high impedance wideband amplifiers, designed specifically to drive a CRT. It features no crossover distortion for excellent gray scale linearity. This device can drive monitors with resolutions of 1280 x 1024 (non-interlaced) with pixel frequency of 160MHz. Rise/Fall Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.0ns Swing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65VP-P Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90V Excellent Gray Scale Linearity Consistent EMI Performance The part is housed in the industry standard 11-lead TO-220 molded power package. The heat sink is grounded. APPLICATIONS • • CRT driver for up to 69kHz monitors with resolution up to 1280 x 1024. Excellent Gray Scale Linearity ORDERING INFORMATION Part Package Temperature CVA2405T T11A -20oC to +100oC CONNECTION DIAGRAM AND SIMPLIFIED SCHEMATIC VCC 9 11 10 VIN 1 9 8 R1 VBIAS VIN 2 VIN 3 R4 7 GND 6 VOUT 1,3,5 VCC 5 R5 VOUT 3 4 GND 3 VOUT 2 R1 VBIAS 2 10 GND 1 R6 VOUT 1 R3 VIN GND = TAB TOP VIEW T11A PACKAGE 11,9,8 R2 1P-12 1P-13 TAB = GND 2,4,7 CALOGIC CORPORATION, 237 Whitney Place, Fremont, California 94539, Telephone: 510-656-2900, FAX: 510-651-3025 CVA2405T CORPORATION ABSOLUTE MAXIMUM RATINGS Supply Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90V Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16W Storage Temperature . . . . . . . . . . . . . . . . . . . -50oC to +150oC ESD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2000V Operating Temperature . . . . . . . . . . . . . . . . . -20oC to +100oC Lead Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . +300oC DC ELECTRICAL CHARACTERISTICS Vs = 80V, CL = 8pF, DCINPUT BIAS = 12V, VIN = 2.6V, VOUT = 50Vp-p. TCASE = +25oC. See Figure 1. SYMBOL CHARACTERISTICS MIN TYP MAX UNITS 30 mA Icc Supply Current, Per Channel 20 IB Bias Current 40 VOUT DC Output DC Level 47 50 53 V Av Voltage Gain -11 -13 -15 V Gain Matching mA 0.5 dB AC ELECTRICAL CHARACTERISTICS Vs = 80V, CL = 8pF, DCINPUT BIAS = 12V, VIN = 2.6V, VOUT = 40Vp-p. TCASE = +25oC. See Figure 1. SYMBOL CHARACTERISTICS MIN TYP MAX UNITS Tr Rise Time 6 ns Tf Fall Time 6 ns Le Linearity 5 % FIGURE 1. TEST CIRCUIT VCC C3 C1 D1 6 VBIAS 10 C2 C4 CVA2405T VIN VOUT 1,3,5 VIDEO 11,9,8 INPUT C6 D2 TEKTRONIX FET PROBE MODEL 6201 (CAP. 1.5pF) 2,4,7 GND TAB C1 = 0.01µF C2 = 100µF C3 = 0.1µF C4 = 100µF C6 = 8pF D1, D2 = FHD400 1P-14 CALOGIC CORPORATION, 237 Whitney Place, Fremont, California 94539, Telephone: 510-656-2900, FAX: 510-651-3025 CVA2405T CORPORATION FIGURE 2. +80V VBIAS L CVA2405T 33 Ω R 91 Ω SPARK GAP VIDEO 1P-15 FIGURE 3. +80V 1K VBIAS L CVA2405T VIDEO 33 Ω R C CVA4501 V cc SPARK GAP DC BIAS I.C. 1P-16 BIAS APPLICATION INFORMATION The CVA2405T is a high voltage triple CRT driver suitiable to drive 69kHz, 1280 x 1024 CRT displays. It features a high impedance input to match any pre-amplifier. The CVA2405T has a true class AB output stage that results in excellent gray scale linearity and consistent EMI performance. As with any high speed amplifier used in CRT display applications, specific precaution should be taken to get the required performance. Power supply should be by pass as close to the device pin as possible. Use 0.01µf very near to the device and a large capacitor of 10µf or more (preferable 100µf) near the device. A 0.1µf and 10µf should be connected near the Vbias pin (#10). Arc protection is very essential. Fast diodes together with the spark gap will achieve sufficient protection. However, in certain applications depends on the tubes a high value of resistor is required to reduce the current into the CVA2405T during arcing. This will result in less than desireable performance some of which can be restored by using a peaking inductor at the output pin, Figure 2. Another way to achieve this is by using a RC network at the output of the device and use a peaking inductor at the tube, Figure 3. The rise and fall time of the CVA2405T may suffer due to stray capacitances associated with the PC Board and other components. It can be improved by carefully designing the PC Board where the output stage and input stage ground path are seperated. Calogic will assist customers in the layout of the PC Board that will result in quick EMI passage and better performance. The output peaking should be used only to restore the performance loss due to stray capacitances. Over peaking will cause excessive ringing that will have better results but poor EMI. The DC restore circuit is also important when considering the high frequency performance. Using CVA4501, DC Bias IC, better results can be obtained and high frequency performance can be maximixed. THERMAL CONSIDERATIONS Power supply current increases as the input signal increases and consequently power dissipation also increases. The CVA2405T cannot be used without heat sinking. Figure 4 shows the power dissipated in each channel over the operating voltage range of the device. Under white screen conditions, i.e.: 25V output, dissipation increases to 10.8W total. The CVA2405T case temperature must be maintained below +100oC. If the maximum expected ambient temperature is +50oC, then a heat sink is needed with thermal resistance equal to or less than: Rth = (100 − 50oC) = 4.6oC/W 10.8W The CVA2405T maximum load is 600Ω to ground or V+. The output of CVA2405T is not short circuit proof. Any resistance to V+ or Ground should be > 600Ω. CALOGIC CORPORATION, 237 Whitney Place, Fremont, California 94539, Telephone: 510-656-2900, FAX: 510-651-3025 CVA2405T CORPORATION FIGURE 4. APPLICATION CIRCUIT VCC 6 C3 R2 VBIAS D1 10 C1 C4 C2 CVA2405T VIN L VOUT 1,3,5 C5 VIDEO 11,9,8 INPUT R3 R1 D2 SPARK GAP DC BIAS 2,4,6 GND TAB R1 = 820Ω R2 = 22Ω R3 = 47(1/2W)Ω C1 = 0.01µF C2 = 100µF C3 = 0.1µF C4 = 100µF C5 = 2.2µF C7 = 40 - 120pf D1, D2 = FHD400 L = 150 - 33nH 1P-17 TYPICAL CHARACTERISTICS VOUT vs VIN 16 70 14 60 12 50 40 30 POWER DISSIPATION vs VCC V OUT = 25V POWER (W) VOUT (V) 80 10 8 6 20 4 10 2 V OUT = VCC = 10V 0 0 0 1 2 3 4 VIN (V) 5 6 7 55 1P-18 60 65 70 75 VCC (V) 80 85 1P-19 PULSE RESPONSE BANDWIDTH 0 VOLTS (V) 10V/DIV. 5 dB / DIV. 5 10 15 20 25 30 1MHz 10MHz 100MHz 1P-20 TIME = 20ns/DIV. 1P-21 CALOGIC CORPORATION, 237 Whitney Place, Fremont, California 94539, Telephone: 510-656-2900, FAX: 510-651-3025