www.fairchildsemi.com ML6428 S-Video Filter and 75Ω Line Drivers with Summed Composite Output Features General Description • • • • • • • • • The ML6428 is a dual Y/C 4th-order Butterworth lowpass video filter optimized for minimum overshoot and flat group delay. The device also contains a summing circuit to generate filtered composite video. • • • • 6.7MHz Y and C filters, with CV out for NTSC or PAL 75Ω cable line driver for Y, C, CV, and TV modulator 43dB stopband attenuation at 27MHz 1dB flatness up to 4.8MHz No external frequency select components or clocks 12ns group delay flatness up to 10MHz 5% overshoot on any input edge AC coupled input and output (ML6428CS-1) AC coupled input and DC coupled output (ML6428CS-2) 0.4% differential gain on all channels, 0.4º differential phase on all channels 0.7% total harmonic distortion on all channels 5V ±10% operation DC restore with low tilt The Y and C input signals from DACs are AC coupled into the ML6428. Both channels have DC restore circuitry to clamp the DC input levels during video sync. The Y channel uses a sync tip clamp. The CV and the C channels share a feedback clamp. All outputs must be AC coupled into their loads for the -1 version. The -2 version must be DC coupled. All inputs (-1 and -2 versions) are AC coupled. The Y or C outputs can drive 2VP-P into a 150Ω load, while the CV output can drive 2VP-P into 75Ω. Thus the CV output is capable of driving two independent 150Ω loads to 2VP-P. On the CV output, one of the 75Ω loads can be shorted to ground with no loss of drive to the remaining load. The Y, C and CV channels have a gain of 2 (6dB) with 1VP-P input levels. Block Diagram YIN VCC VCCO 2 7 4th-ORDER FILTER 1 8 YOUT 6 CVOUT 5 COUT BUFFER + SYNC TIP CLAMP Σ TRANSCONDUCTANCE ERROR AMP CIN 4 4th-ORDER FILTER BUFFER + BUFFER 3 GND REV. 1B April 2003 ML6428 DATA SHEET Pin Configuration ML6428 8-Pin SOIC (S08) YIN 1 8 YOUT VCC 2 7 VCCO GND 3 6 CVOUT CIN 4 5 COUT TOP VIEW Pin Description Pin Name Function 1 YIN Luminance input 2 VCC 5V supply for filters and references 3 GND Ground 4 CIN Chrominance input 5 COUT 6 CVOUT Composite video output 7 VCCO 5V supply for output stages 8 YOUT Luminance output Chrominance output Electrical Characteristics Absolute Maximum Ratings Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. Parameter Min. Max. Units DC Supply Voltage -0.3 7 V Analog & Digital I/O GND – 0.3 VCC + 0.3 V Output Current (Continuous) CV Channel C and Y Channels 60 30 mA mA Junction Temperature 150 °C 150 °C Lead Temperature (Soldering, 10 sec) 260 °C Thermal Resistance (θJA) 67 °C/W Min. Max. Units 0 70 °C 4.5 5.5 V Storage Temperature Range –65 Operating Conditions Parameter Temperature Range VCC Range 2 REV. 1B April 2003 DATA SHEET ML6428 Electrical Table Unless otherwise specified, VCC = 5V ±10%, All inputs AC coupled with 100nF, ML6428-1 outputs must be AC coupled, ML6428-2 outputs must be DC coupled. TA = Operating Temperature Range1 Symbol ICC AV Parameter Conditions Min. Typ. Max. Units No Load (VCC = 5.0V) VIN = 100mVP-P at 300KHz Sync Present on Y Sync Present on Y 5.34 1.7 0.7 52 6.0 1.9 0.9 80 6.65 2.3 1.3 mA dB V V ML6428-2 Sync Present on Y 0.35 0.54 0.95 V ML6428-1 Sync Present on Y 0.7 0.92 1.3 V ML6428-2 Sync Present on Y 0.35 0.48 0.95 V 4.0 2 4.8 ms MHz Supply Current Low Frequency Gain (All Channels) C DC Output Level (During Sync) Y Sync Output Level ML6428-1 Y+C Sync Output Level tCLAMP f1dB Clamp Response Time (Y Channel) -1dB Bandwidth (Flatness) (All Channels) fC -3dB Bandwidth (Flatness) (All Channels) 6.7 MHz 0.8fC 0.8 x fC Attenuation (Y, C) 1.5 dB fSB Stopband Rejection (All Channels) fIN = 27MHz to 100MHz worst case Vi NOISE OS Input Signal Dynamic Range Output Noise (All Channels) Peak Overshoot (All Channels) AC Coupled ML6428-1, -2 25Hz to 50MHz 2VP-P Output Pulse (loaded) ISC Output Short Circuit Current (All Channels) VOUT C, Y, or CV (Note 2) CL Output Shunt Capacitance (All Channels) All Outputs dG dΦ THD Differential Gain (All Channels) Differential Phase (All Channels) Output Distortion (All Channels) All Outputs All Outputs VOUT = 1.8VP-P, Y/C Out at 3.58MHz/4.43MHz 0.4 0.4 0.7 % ° % XTALK Crosstalk From C Input of 0.5VP-P at 3.58MHz/4.43MHz, to Y Output –55 dB From Y Input of 0.4VP-P at 3.58MHz, to C Output –58 dB 0.5VP-P (100kHz) at VCC 100kHz to 3.58MHz (NTSC) –49 60 4 dB ns ns to 4.43MHz (PAL) without peaking (see Figures 7 to 11) 7 ns to 10MHz 12 ns PSRR tpd ∆tpd tSKEW Note PSRR (All Channels) Group Delay (All Channels) Group Delay Deviation from Flatness (All Channels) Settled to Within 10mV –42 1.0 –38 dB 1.4 2.3 4.3 VP-P mVRMS % 100 mA 35 Skew Between Y & C Outputs 1 pF ns 1: Limits are guaranteed by 100% testing, sampling, or correlation with worst case test conditions. 2: Sustained short circuit protection limited to 10 seconds. REV. 1B April 2003 3 ML6428 Functional Description The ML6428 is a dual monolithic continuous time video filter designed for reconstructing the luminance and chrominance signals from an S-Video D/A source. Composite video output is generated by summing the Y and C outputs. The ML6428CS-1 is intended for use in AC coupled input and output applications. The ML6428CS-2 is intended for AC coupled input and DC coupled output applications (see Figures 5 and 6). The filters have a 4th-order Butterworth characteristic with an optimization toward low overshoot and flat group delay. All outputs are capable of driving 2VP-P into 150Ω video loads, with up to 35pF of load capacitance at the output pin. ML6428CS-1 outputs are AC coupled, ML6428CS-2 outputs are DC coupled. The CV output can drive two video loads plus a high-impedance modulator. Thus the CV output is intended to simultaneously drive a VCR, a TV, and a highimpedance modulator. Y and C are capable of driving a 75Ω load at 1VP-P. The ML6428 is capable of driving two composite loads and a TV modulator simultaneously. All channels are clamped during sync to establish the appropriate output voltage swing range. Thus the input coupling capacitors do not behave according to the conventional RC time constant. Clamping for all channels settles within 2ms of a change in video input sources. In most applications, the ML6428's input coupling capacitors are 0.1µF. The Y input sinks 1.6µA during active video, which nominally tilts a horizontal line by 2mV (max) at the Y output (Figure 4). During sync, the clamp typically sources 20µA to restore the DC level. The net result is that the average input current is zero. Any change in the input coupling capacitor's value will inversely alter the amount of tilt per line. Such a change will also linearly affect the clamp response times. The C channel has no pulldown current sources and is essentially tilt-free. Its input is clamped by a feedback amp which responds to the CV output. Since CV = Y+C, the CV output will droop by the same amount as Y during active video, and will rise by the same amount as Y during sync. The ML6428 is robust and stable under all stated load and input conditions. Capacitavely bypassing both VCC pins directly to ground ensures this performance. (See Figures 5 and 6) DATA SHEET capacitance (at the output pin) can be driven without stability or slew issues. A 220µF AC coupling capacitor is recommended at the output (ML6428-1 only). Chrominance (C) I/O The chroma input is driven by a low impedance source of 0.7VP-P or the output of a 75Ω terminated line. The input is required to be AC coupled via a 0.1uF coupling capacitor which allows for a nominal clamping time of 1ms. The chroma output is capable of driving a 150Ω load at 2VP-P or 1VP-P into a 75Ω load. ML6428CS-1 outputs are AC coupled, ML6428CS-2 outputs are DC coupled. Up to 35pF of load capacitance can be driven without stability or slew issues. A 220µF AC coupling capacitor is recommended at the output (ML6428-1 only). Composite video (CV) output The composite video output is capable of driving 2 CV loads to 2VP-P and a high input impedance CV modulator. ML6428CS-1 outputs are AC coupled, ML6428CS-2 outputs are DC coupled. It is intended to drive three devices: TV, VCR, and a modulator. The TV or VCR input can be shorted to ground and the other outputs will still meet specifications. Up to 35pF of load capacitance (at the output pin) can be driven without stability or slew issues. Using the ML6428 for PAL Applications The ML6428 can be optimized for PAL video by adding frequency peaking to the composite and S-video outputs. Figures 7 and 8 illustrate the use of a additional external capacitor, 330pF, added in parallel to the output source termination resistor. This raises the frequency response from 1.6 dB down at 4.8Mhz to 0.35dB down at 4.8MHz allowing for accurate reproduction of the upper sideband of the PAL subcarrier. Figure 9 shows the frequency response of PAL video with various values of peaking capacitors (0pF, 220pF, 270pF, 330pF) between 0 and 10MHz. For NTSC applications without the peaking capacitor the rejection at 27MHz is 42dB (typical) while for PAL applications with the peaking capacitor the rejection at 27MHz is 38dB (typical). This is shown in Figure 10. The differential group delay is shown in Figure 11 with and without a peaking capacitor (0pF, 220pF, 270pF, and 330pF) varies slightly with capacitance, going from 8ns to 13ns. Luminance (Y) I/O The luma input is driven by either a low impedance source of 1VP-P or the output of a 75Ω terminated line. The input is required to be AC coupled via a 0.1uF coupling capacitor which allows for a nominal settling time of 2ms. The luma output is capable of driving a 150Ω load at 2VP-P or 1VP-P into a 75Ω load. ML6428CS-1 outputs are AC coupled, ML6428CS-2 outputs are DC coupled.Up to 35pF of load 4 REV. 1B April 2003 ML6428 1 20 0 0 AMPLITUDE (dB) AMPLITUDE (dB) DATA SHEET –1 –2 –3 –20 –40 –60 –4 0 0.1 1 –80 0.01 10 FREQUENCY (MHz) 0.1 1 10 100 FREQUENCY (MHz) Figure 2. Passband/Stopband Rejection Ratios All outputs. (Normalized) Figure 1. Passband Flatness All outputs. (Normalized) Passband is ripple-free. 90 SCALE: 200ms/DIV DELAY (ns) 70 50 30 Region of Tilt 10 1 2 3 4 5 6 7 8 9 10 11 FREQUENCY (MHz) Figure 3. Group Delay, all Outputs Low frequency group delay is 62ns. At 3.58MHz group delay increases by only 4ns. At 4.43MHz group delay increases by only 7ns. The maximum deviation from flat group delay of 12ns occurs at 6MHz. REV. 1B April 2003 SCALE: 200ms/DIV Figure 4. DC Restore Performance of Luma Output Luma ramp test pattern is shown to have minimal tilt during vertical sync. In most applications, the ML6428's input coupling capacitors are 0.1µF. The Y input sinks 1.6µA during active video, which tilts a horizontal line by 2mV at the Y output 5 ML6428 DATA SHEET Typical Applications ML6428-1 0.1µF 220µF 1 YIN 8 4th-ORDER FILTER 75Ω VIDEO CABLES YOUT 75Ω + 220µF 6 Σ 75Ω CVOUT 75Ω + 0.1µF 220µF 4 CIN 5 4th-ORDER FILTER 75Ω CVOUT 75Ω C* 2 7 R* 3 ON-CHANNEL MODULATOR, VCR, AND TV 5V 220µF 75Ω COUT 0.1µF 75Ω 1µF * C AND R DEPEND ON THE INPUT IMPEDANCE OF LOAD Figure 5. AC Coupled S-Video and Composite Video Line Driver for NTSC (Note: ML6428-1 outputs must be AC coupled) ML6428-2 0.1µF 1 YIN VIDEO CABLES 75Ω 8 4th-ORDER FILTER YOUT 75Ω + 75Ω 6 Σ CVOUT 75Ω + 0.1µF CIN 4 75Ω 5 4th-ORDER FILTER CVOUT 75Ω C* 2 7 R* 3 ON-CHANNEL MODULATOR, VCR, AND TV 5V 75Ω COUT 75Ω 0.1µF 1µF * C AND R DEPEND ON THE INPUT IMPEDANCE OF LOAD Figure 6. DC Coupled S-Video and Composite Video Line Driver for NTSC (Note: ML6428-2 outputs must be DC coupled) 6 REV. 1B April 2003 DATA SHEET ML6428 Typical Applications ML6428-1 0.1µF 220µF 1 YIN 8 4th-ORDER FILTER VIDEO CABLES 75Ω YOUT 75Ω + 330pF 220µF 6 Σ 75Ω CVOUT 75Ω 330pF + 0.1µF 220µF 4 CIN 5 4th-ORDER FILTER 75Ω CVOUT 75Ω C1* 2 7 3 330pF ON-CHANNEL MODULATOR, VCR, AND TV R* 5V 220µF 0.1µF C2* 75Ω COUT 75Ω 1µF 330pF * C1, C2, AND R DEPEND ON THE INPUT IMPEDANCE OF LOAD Figure 7. AC Coupled S-Video and Composite Video Line Driver for PAL (Note: ML6428-1 outputs must be AC coupled) ML6428-2 0.1µF 1 YIN 75Ω 8 4th-ORDER FILTER VIDEO CABLES YOUT 75Ω + 330pF 75Ω 6 Σ CVOUT 75Ω 330pF + 0.1µF CIN 4 75Ω 5 4th-ORDER FILTER CVOUT 75Ω C1* 2 7 3 330pF ON-CHANNEL MODULATOR, VCR, AND TV R* C2* 5V 75Ω COUT 75Ω 0.1µF 1µF 330pF * C1, C2, AND R DEPEND ON THE INPUT IMPEDANCE OF LOAD Figure 8. DC Coupled S-Video and Composite Video Line Driver for PAL (Note: ML6428-2 outputs must be DC coupled) REV. 1B April 2003 7 ML6428 DATA SHEET –0.5 0.35dB WITH PEAKING AMPLITUDE (dB) 0 0.5 1.7dB WITHOUT PEAKING 1 1.5 330pF 270pF 2 220pF 0pF 2.5 0 2 1 4 3 6 5 8 7 FREQUENCY (MHz) Figure 9. NTSC/PAL Video Frequency Response With and Without Peaking Capacitor 0 AMPLITUDE (dB) 10 NTSC/PAL –38dB WITH PEAKING 20 30 NTSC/PAL –42dB WITHOUT PEAKING 330pF 40 270pF 220pF 0pF 50 0 3 6 9 12 15 18 21 24 27 30 FREQUENCY (MHz) Figure 10. Stopband Rejection at 27MHz With and Without Peaking Capacitor 10 8ns GROUP DELAY WITHOUT PEAKING DELAY (ns) 0 13ns GROUP DELAY WITH 330pF PEAKING –10 330pF 270pF 220pF 0pF –20 0 1 2 3 4 5 6 7 8 9 10 FREQUENCY (MHz) Figure 11. Group Delay at 5.5MHz (PAL) With and Without Peaking Capacitor 8 REV. 1B April 2003 DATA SHEET ML6428 Mechanical Dimensions inches (millimeters) Package: S08 8-Pin SOIC 0.189 - 0.199 (4.80 - 5.06) 8 PIN 1 ID 0.148 - 0.158 0.228 - 0.244 (3.76 - 4.01) (5.79 - 6.20) 1 0.017 - 0.027 (0.43 - 0.69) (4 PLACES) 0.050 BSC (1.27 BSC) 0.059 - 0.069 (1.49 - 1.75) 0° - 8° 0.055 - 0.061 (1.40 - 1.55) 0.012 - 0.020 (0.30 - 0.51) 0.004 - 0.010 (0.10 - 0.26) 0.015 - 0.035 (0.38 - 0.89) 0.006 - 0.010 (0.15 - 0.26) SEATING PLANE REV. 1B April 2003 9 ML6428 DATA SHEET Ordering Information Part Number Temperature Range Package ML6428CS-1 0°C to 70°C 8 Pin SOIC (S08) ML6428CS-2 0°C to 70°C 8 Pin SOIC (S08) DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. 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A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. © 2003 Fairchild Semiconductor Corporation