CCVGA7C5

UNISONIC TECHNOLOGIES CO., LTD CCVGA7C5 Preliminary TVS VGA PORT COMPANION CIRCUIT  DESCRIPTION The UTC CCVGA7C5 is an ESD solution for the VGA port connector. This device integrates ESD protection for all signals, Two non-inverting drivers provide buffering for the HSYNC and VSYNC signals from the video controller IC. These buffers accept TTL input levels and convert them to CMOS output levels that swing between Ground and VCC 。 These drivers have a nominal 60Ω output impedance to match the characteristic impedance of the HSYNC and VSYNC lines of the video cables typically used. The inputs of these drivers also have high impedance pull−ups (50kΩ nom.) pulling up to the VAUX rail. In addition, the DDC_CLOCK and DDC_DATA channels have 1.8kΩ resistors pulling these inputs up to the main 5V (VCC) rail. The upper ESD diodes for the R, G and B channels are connected to a separate supply rail (VRGB) to facilitate interfacing to graphics controller ICs with low voltage supplies. The remaining channels are connected to the main 5 V rail (VCC). The lower diodes for the R, G and B channels are also connected to a dedicated ground pin (GNDA) to minimize crosstalk due to common ground impedance. ESD protection is implemented with current steering diodes designed to safely handle the high peak surge currents associated with the IEC−1000−4−2 Level−4 ESD Protection Standard (±8kV contact discharge). When the channels are subjected to an electrostatic discharge, the ESD current pulse is d...