Features: Single 4th-order 8 MHz (SD) filter drives single AC or DC coupled video load (2 vpp, 150 Ω) Drives dual AC or DC coupled video loads (2 vpp, 75 Ω) Transparent input clamps AC or DC coupled input AC or DC Coupled Output DC Coupled Output Eliminates AC Coupling Capacitors Single Supply Robust 8 kV ESD Protection Lead Free Package: SOIC-8 or SC70-5

Application: Cable STB Satellite STB DVD Player HDTV Personal Video Recorder (PVR) Video on Demand (VOD)

Description: The FMS6141 low cost video filter is designed to replace low cost integrated passive lc filter and driver units. A fourth-order filter provides improved image quality resolution compared to typical second- or third-order passive systems. The FMS6141 can directly drive the DAC output or AC-coupled signals by DC coupling. Internal diode clip if AC-coupled input is required (see Application Information for details). The output of the FMS6141 can drive AC or DC coupled single (150Ω) or dual (75Ω) loads. DC-coupled outputs do not require output coupling capacitors. This input DC level is offset by about ± 280 mV.

Absolute Maximum Ratio Pressure exceeding the Absolute Maximum Ratio may damage the equipment. The device may or may not work. Above the recommended operating conditions and stressing the parts to these levels is not recommended. Plus Extended exposure to stresses above the recommended operating conditions may affect device reliability. Absolute maximum ratios are stress ratios only.

Application Information: Input Considerations The FMS6141 low-cost video filter provides 6dB (2x) gain from input to output. The device provides internal diode clamps that support AC-coupled input signals. In this configuration, a 0.1µf ceramic capacitor is used to AC connect the input signal. If the input signal does not work below ground, the clamp does not work; but if the input signal is below ground, the clamp circuit sets the sync tip (or low EST voltage) just below ground. This clamp sets the input level, combined with the internal DC offset, to keep the output signal within an acceptable range. This clamping feature also allows the input of the FMS6141 to directly drive (DC coupled) the DAC output with reference to ground. The figure shows the input output signal dac output for DC coupled drive or AC coupled and clamped y, cv signal.

Output Considerations The DC offset of the FMS6141 output and input is 150mV, so VOUT=2*VINDC+150mV. This offset is required for optimum performance from the output and kept to a minimum in order to reduce the continuous DC current of the input load. Since the FMS6141 has a gain of 2x (6dB), the output is typically connected to a 75Ω video cable through a 75Ω series reverse matched resistor. Because of the inherent division of To by this configuration, the blanking level is typically less than 1V at the load of the video signal. When AC coupling the output make sure that coupling capacitors are selected through the video signal and line time distortion (video skew) is kept as low as possible. The choice of coupling capacitor is the input impedance of the subsequent circuit and the current that leaks the driven input. To obtain the highest quality output video signal series terminating resistors must be placed as close to the device output pins as possible. This greatly reduces the effect of parasitic capacitance and inductance on the fms6141 output driver. It is recommended that the series termination resistance from the device pin to the Place be no greater than 0.1 inches.

The I/O configuration diagram shows a typical AC-coupled input configuration used to drive the filter/driver. With this configuration, a 0.1µf ceramic capacitor is used to AC couple the input signal. Coupling Capacitors and Input Resistors should be placed at the input of the filter/driver close to the input pins for best signal integrity.

Diagram Concept Diagram - Input Clamp Circuit and Output Drivers Connected to Drivers for Single or Dual Video Loading

Layout Considerations General layout and power supply bypass performance and thermal characteristics at high frequency. OnSemiconductor for FMS6141 is used to guide layout and assist device evaluation. This demo board is a four layer board with full power and ground plane. Following this layout configuration provides the best performance and thermal characteristics of the device. For best results, follow the steps and suggested routing rules listed below. Recommended routing/layout rules Do not run analog and digital signals in parallel. Power the POW using separate analog and digital power strips. There should be trace times at the top of the ground plane. There must be no traces on the ground/power splitter. Avoid wiring at 90-degree angles. Minimize clock and video data trace length differences. Includes 10µF and 0.1µF ceramic power supply bypass capacitors. Place a 0.1µF capacitor at the device power pins. Place a 10µF capacitor at the device power pins. For multi-layer boards, use a large ground plane to help dissipate heat. For TW O laminates, use an extended ground plane at least 0.5 inches beyond the device body. The top layer below the device. Minimize all trace lengths to reduce series inductance. Thermal factor because the internals of most systems, such as set-top boxes, TVs and DVD players are +70°C; please consider that maximum cooling is required. when? Design the system board so that power is dissipated by each device. Make sure that the height power supply of the device is not in the same location, e.g. directly above (top plane) and below (bottom plane) other on the printed circuit board. PCB Thermal Layout Considerations Learn about system power requirements and environmental conditions. Maximize the thermal performance of your PCB. Consider using 70µm copper for high power designs. Make the pcb as thin as possible by reducing the fr4 thickness. Connect adjacent layers together with the vias on the power board. Remember, the base temperature is the board area, not the copper thickness. Modeling techniques can provide approximations.

Power dissipation Considering the output drive configuration of the FMS6141 calculates the total power dissipation. Care must be taken not to exceed the maximum die junction temperature. This following example can be used to calculate the power dissipation and internal temperature of the FMS6141. The FMS6141 is specified to operate at an output current typically less than 50mA, which is sufficient for dual (75Ω) video loading. The current limit of the internal amplifier of the FMS6141 is 100 mA maximum. Can withstand short short circuit conditions, but this ability is not guaranteed.