GB4571-CTA

GB4571 Video Buffer with Precision Strobed DC Restore DATA SHEET FEATURES accurate clamping to within ± 1 mV less than 1 mV clamping distortion variable clamping range (VEE + 3.0 V to VCC - 4.5 V) ultra low differential gain and differential phase fast recovery from sudden changes in DC offsets less than ± 0.15° phase delay variation at 3.58 MHz ± 0.1 dB flatness to 80 MHz ± 4.5 V to ±13.2 V supply voltage range DESCRIPTION The GB4571 is a high performance video buffer with DC restore used primarily for accurate back porch clamping. Key features include operation from ± 4.5 V to ± 13.2 V supply voltages, fast recovery from sudden changes in DC offset, ± 0.1 dB flatness to 80 MHz and availability of industry standard DIP and SOIC packages. In the typical back porch clamping application, a negative going back porch pulse from an external sync separator (such as the GS4881 or GS4882) is applied to the GB4571's STROBE input. While STROBE is low, the GB4571 determines the correct DC level shift that should be applied to the input signal by integrating over the entire back porch period. This reduces sensitivity to noise and improves the accuracy of the DC restoration compared to systems using sample and hold techniques. Typical clamping accuracy of ± 1 mV is achieved by the GB4571. APPLICATIONS PIN CONNECTIONS GB4571 C HOLD V IN V CLAMP STROBE 1 2 3 4 8 7 6 5 VCC VOUT VEE GND Clamping of NTSC, PAL, SECAM & RGB Video Signals Multimedia Graphics Overlay P...