185MHz CRT Driver CORPORATION CVA3424A / CVA3424 FEATURES DESCRIPTION • Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185MHz • Rise/Fall Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5ns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40VP-P • Swing • Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80V The CVA3424 Family is a video driver amplifier designed specially to drive high resolution color monitors. With rise and fall time of under 2.5ns and 185MHz bandwidth, this device will provide excellent drive capability for the 2000 x 1600, 1600 x 1280 and 1280 x 1024 monitors. APPLICATIONS • CRT Driver for 2000 x 1600, 1600 x 1280 and 1280 x 1024 ORDERING INFORMATION Monitors Part Package Temperature CVA3424AT CVA3424T TO-220 TO-220 -20oC to +90oC -20oC to +90oC CONNECTION DIAGRAM AND SIMPLIFIED SCHEMATIC 11 10 9 8 7 6 5 4 3 2 1 VCC 11 Vcc NC RF Vout GND Vin GND 3 RB NC 142Ω CVA3424 Vout 9 NC Vin NC GND 6,7,8 NC PIN 1 DESIGNATOR T11A 3.66kΩ GND 1C-04 1B-04 CVA3424A / CVA3424 CORPORATION ABSOLUTE MAXIMUM RATINGS Operating Temperature . . . . . . . . . . . . . . . . . -20oC to +90oC Lead Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . +300oC Supply Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85V Storage Temperature . . . . . . . . . . . . . . . . . . -25oC to +100oC DC ELECTRICAL CHARACTERISTICS VS = 80V, CL = 10pF, Vout = 40Vp-p. See Figure 1. TA = +125oC unless otherwise noted. SYMBOL CHARACTERISTICS MIN TYP MAX UNITS 45 55 mA ICC Supply Current VinDC Iput DC Level 1.4 1.6 1.8 V VoutDC Output DC Level 34 40 46 V AV Voltage Gain 11 13 15 V Gain Matching 0.2 dB AC ELECTRICAL CHARACTERISTICS VS = 80V, CL = 10pF, Vout = 40Vp-p. See Figure 1. TA = +125oC unless otherwise noted. CVA3424A SYMBOL CVA3424 CHARACTERISTICS UNITS MIN TYP MAX MIN TYP MAX tr Rise Time 2.2 2.9 2.5 3.5 ns tf Fall Time 2.5 2.9 2.7 3.5 ns BW Bandwidth 185 150 MHz Le Linearity 5 5 % OS / US Overshoot / Undershoot 8 8 % FIGURE 1. TEST CIRCUIT C3 C2 C4 R4 R2 11 R1 INPUT VCC 3 CVA3424 Vin 9 R5 C6 VC C 1 D1 R6 L1 OUTPUT Vout D2 CL 6,7,8 GND R1 = 270 Ω R2 = 12k Ω (1 W) R4 = 300k Ω R5 = 15 Ω R6 = 15 Ω C2 = Variable 4 to 150pF Typical 27pF C3 = 46pF C4 = 10 µf/160V C6 = 0.01 µf/160V C L = 10pF (Including Parasitics) D1 = DS464 D2 = DS464 L1 = 150nH 1B-05 CVA3424A / CVA3424 CORPORATION APPLICATIONS INFORMATION Basic Circuit Configuration Output Characteristics The CVA3424 is a 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 CVA3424 into a voltage amplifier. The output is an emitter follower. Because of the complementary circuitry employed, there is no need for load or pull up resistor. The CVA3424 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 30-50Ω will provide protection but will slow down the response. The lead inductance may be artificially 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). An internally bypassed capacitor is included inside the package, however, for low frequencies an electrolytic capacitor is recommended. CVA3424 has an internal feedback resistor of 3.66KΩ. In the absence of any input signal, the Vout DC is set by Vout (DC) = (1 + CL R∗ = √ RF ) V (DC) RB in The output of CVA3424 is not short circuit proof. Any resistance to V+ or Ground should be >600Ω. If an input signal is applied, the gain is set by RF ) Vin Rx Thermal Characteristics Input and Transfer Characteristics An input current swing of ±4.5mA causes the output to change by ±25V. A resistor of 270Ω in series with the input will give a voltage gain of -13. Input pins are internal dc feedback nodes and thus have low impedances. These pins must be fed from a series RC network for high frequency emphasis. FALL TIME 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 300kΩ and 46pF values. Under normal operating conditions the CVA3424 will dissipate up to 6W. The maximum allowed case temperature is +90oC. To calculate maximum heatsink thermal resistance use equation (2). Rth = (90 − 50°) = 6.7°C/W 6W RISE TIME BANDWIDTH VOLTS 8V/DIV VOLTS 8V/DIV 0dB GAIN 5dB/DIV Vout = ( (1) 2ns/DIV 2ns/DIV 1 10 100 MHz CVA3424 CORPORATION Information furnished by Calogic is believed to be accurate and reliable. However, no responsibility is assumed for its use: nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent rights of Calogic. CALOGIC CORPORATION, 237 Whitney Place, Fremont, California 94539, Telephone: 510-656-2900, FAX: 510-651-1076