ADA4430-1

Ultralow Power Video Filter with Power-Down ADA4430-1 FEATURES 6th-order performance, low-pass video filter 1 dB flatness out to 8 MHz 50 dB rejection at 27 MHz Ultralow power-down current: 0.1 μA typ Low quiescent current: 1.85 mA typ Excellent video specification Differential gain: 0.25% Differential phase: 0.10° SAG correction Allows use of small capacitors in ac-coupled outputs Low supply voltage: 2.5 V to 6 V Rail-to-rail output High input-to-output isolation in disabled state 92 dB @ 1 MHz Low input bias current: 0.5 μA Small packaging: SC70 Wide operating temperature range: −40°C to +125°C GAIN (dB) VIN 1 PIN CONFIGURATION ADA4430-1 x1 6 VS+ GND 2 2*R 5 R PD Figure 1. 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 VS = 5V APPLICATIONS Portable media players Portable gaming consoles Cell phones Digital still cameras Portable DVD players Portable video cameras 05885-001 SAG 3 2*R 2*R 4 VOUT VS = 3V 1 FREQUENCY (MHz) 10 Figure 2. Frequency Response Flatness at Various Power Supplies GENERAL DESCRIPTION The ADA4430-1 is a fully integrated video reconstruction filter that combines excellent video specifications with low power consumption and an ultralow power disable, making it ideal for portable video filtering applications. With 1 dB frequency flatness out to 8 MHz and 50 dB rejection at 27 MHz, the ADA4430-1 is ideal in SD video applications, including NTSC and PAL. The ADA4430-1 operates on single supplies as low as 2.5 V and as high as 6 V while providing the dynamic range required by the most demanding video systems. The ADA4430-1 also provides an on-chip dc offset to avoid clipping of the sync tips at the filter output, as well as SAG correction that permits smaller capacitor values to be used in applications with ac-coupled outputs. The ADA4430-1 is available in a 6-lead SC70 package and is rated to work in the extended automotive temperature range of −40°C to +125°C. Rev. A Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2006 Analog Devices, Inc. All rights reserved. 05885-006 ADA4430-1 TABLE OF CONTENTS Features .............................................................................................. 1 Applications....................................................................................... 1 Pin Configuration............................................................................. 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Absolute Maximum Ratings............................................................ 4 Thermal Resistance ...................................................................... 4 ESD Caution.................................................................................. 4 Pin Configuration and Function Descriptions............................. 5 Typical Performance Characteristics ............................................. 6 Test Circuits..................................................................................... 10 Theory of Operation ...................................................................... 11 Overview ..................................................................................... 11 Power Savings Using the ADA4430-1 ..................................... 11 Applications..................................................................................... 12 Examples Illustrating Output Coupling .................................. 12 Usable Input Voltage Range ...................................................... 13 SAG Correction Frequency Response ..................................... 13 Reconstruction Filter Applications .......................................... 14 Printed Circuit Board Layout ................................................... 15 Outline Dimensions ....................................................................... 16 Ordering Guide .......................................................................... 16 REVISION HISTORY 6/06—Rev. 0 to Rev. A Changes to Figure 1.......................................................................... 1 Changes to Figure 4.......................................................................... 5 3/06—Revision 0: Initial Version Rev. A | Page 2 of 16 ADA4430-1 SPECIFICATIONS VS = 3 V @ TA = 25°C, VIN = 1 V p-p, RL = 150 Ω, unless otherwise noted. Table 1. Parameter ELECTRICAL SPECIFICATIONS Quiescent Supply Current Quiescent Supply Current—Disabled Supply Voltage Input Voltage Range—Low/High Input Resistance Input Capacitance Input Bias Current Output Voltage Range—Low/High Output Offset Voltage PSRR Pass-Band Gain Input-to-Output Isolation—Disabled FILTER CHARACTERISTICS −3 dB Bandwidth 1 dB Flatness Out-of-Band Rejection Differential Gain Differential Phase Linear Output Current Group Delay Variation Signal-to-Noise Ratio Test Conditions/Comments Min Typ 1.85 0.1 2.5 Limited by output range; see the Applications section 0/1.38 10 1 0.5 0.10/2.85 95 60 6 92 9.7 8.0 50 0.25 0.10 40 7 76 Max 2.3 5 6 Unit mA μA V V MΩ pF μA V mV dB dB dB MHz MHz dB % Degrees mA ns dB 140 Input referred f = 1 MHz 50 5.85 f = 27 MHz Modulated 10 step ramp, sync tip at 0 V Modulated 10 step ramp, sync tip at 0 V f = 100 kHz to 5 MHz 100% white signal, f = 100 kHz to 5 MHz 7 5.5 40 VS = 5 V @ TA = 25°C, VIN = 1 V p-p, RL = 150 Ω, unless otherwise noted. Table 2. Parameter ELECTRICAL SPECIFICATIONS Quiescent Supply Current Quiescent Supply Current—Disabled Supply Voltage Input Voltage Range—Low/High Input Resistance Input Capacitance Input Bias Current Output Voltage Range—Low/High Output Offset Voltage PSRR Pass-Band Gain Input-to-Output Isolation—Disabled FILTER CHARACTERISTICS −3 dB Bandwidth 1 dB Flatness Out-of-Band Rejection Differential Gain Differential Phase Linear Output Current Group Delay Variation Signal-to-Noise Ratio Test Conditions/Comments Min Typ 2.0 0.2 2.5 Limited by output range; See the Applications section 0/2.35 10 1 0.5 0.10/4.80 100 61 6 92 9.5 7.9 50 0.25 0.15 40 7.1 76 Max 2.4 10 6 Unit mA μA V V MΩ pF μA V mV dB dB dB MHz MHz dB % Degrees mA ns dB 145 Input referred f = 1 MHz 50 5.85 f = 27 MHz Modulated 10 step ramp, sync tip at 0 V Modulated 10 step ramp, sync tip at 0 V f = 100 kHz to 5 MHz 100% white signal, f = 100 kHz to 5 MHz Rev. A | Page 3 of 16 7.2 5.5 40 ADA4430-1 ABSOLUTE MAXIMUM RATINGS Table 3. Parameter Supply Voltage Power Dissipation Storage Temperature Range Operating Temperature Range Lead Temperature (Soldering 10 sec) Junction Temperature Rating 6V See Figure 3 –65°C to +125°C –40°C to +125°C 300°C 150°C Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. The power dissipated in the package (PD) is the sum of the quiescent power dissipation and the power dissipated in the package due to the load drive. The quiescent power is the voltage between the supply pins (VS) times the quiescent current (IS). The power dissipated due to the load drive depends upon the particular application. The power due to load drive is calculated by multiplying the load current by the associated voltage drop across the device. RMS voltages and currents must be used in these calculations. Airflow increases heat dissipation, effectively reducing θJA. In addition, more metal directly in contact with the package leads from metal traces, through-holes, ground, and power planes reduces the θJA. Figure 3 shows the maximum safe power dissipation in the package vs. the ambient temperature for the 6-lead SC70 (430°C/W) on a JEDEC standard 4-layer board. 0.50 0.45 MAXIMUM POWER DISSIPATION (W) THERMAL RESISTANCE θJA is specified for the worst-case conditions, that is, θJA is specified for a device soldered in the circuit board. Table 4. Thermal Resistance Package Type 6-Lead SC70 θJA 430 Unit °C/W 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0 –40 –20 0 20 40 60 80 100 120 05885-002 Maximum Power Dissipation The maximum safe power dissipation in the ADA4430-1 package is limited by the associated rise in junction temperature (TJ) on the die. At approximately 150°C, which is the glass transition temperature, the plastic changes its properties. Even temporarily exceeding this temperature limit can change the stresses that the package exerts on the die, permanently shifting the parametric performance of the ADA4430-1. Exceeding a junction temperature of 150°C for an extended period can result in changes in the silicon devices potentially causing failure. AMBIENT TEMPERATURE (°C) Figure 3. Maximum Power Dissipation vs. Temperature for a 4-Layer Board ESD CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. Rev. A | Page 4 of 16 ADA4430-1 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS ADA4430-1 VIN 1 x1 6 VS+ GND 2 2*R 5 R PD Figure 4. 6-Lead SC70, Top View Table 5. Pin Function Descriptions Pin Number 1 2 3 4 5 6 Mnemonic VIN GND SAG VOUT PD VS+ Description Input Voltage. Ground. Feedback Connection. Output Voltage. Power Down. Positive Power Supply. Rev. A | Page 5 of 16 05885-041 SAG 3 2*R 2*R 4 VOUT ADA4430-1 TYPICAL PERFORMANCE CHARACTERISTICS VS = +3 V, RL, = 150 Ω, VOUT = 2.0 V p-p, PD = high, VOUT connected directly to SAG, TA = 25°C, unless otherwise noted. 9 6 3 0 –3 –6 –9 –12 –15 –18 –21 –24 –27 –30 –33 –36 –39 –42 –45 –48 6.5 VS = 3V VS = 5V 5.5 GAIN (dB) 5.0 4.5 4.0 3.5 3.0 6.0 VS = 5V VS = 3V GAIN (dB) 05885-003 1 10 FREQUENCY (MHz) 100 1 FREQUENCY (MHz) 10 Figure 5. Frequency Response at Various Power Supplies 9 6 3 0 –3 –6 –9 –12 –15 –18 –21 –24 –27 –30 –33 –36 –39 –42 –45 –48 Figure 8. Frequency Response Flatness at Various Power Supplies 6.5 RL = 75Ω RL = 75Ω RL = 150Ω 6.0 RL = 150Ω 5.5 GAIN (dB) 5.0 4.5 4.0 3.5 3.0 1 FREQUENCY (MHz) 10 GAIN (dB) 05885-004 1 10 FREQUENCY (MHz) 100 Figure 6. Frequency Response at Various Loads 9 6 3 0 –3 –6 –9 –12 –15 –18 –21 –24 –27 –30 –33 –36 –39 –42 –45 –48 Figure 9. Frequency Response Flatness at Various Loads 6.5 +125°C 6.0 5.5 GAIN (dB) 5.0 –40°C 4.5 4.0 3.5 3.0 1 FREQUENCY (MHz) 10 +125°C +25°C –40°C +25°C GAIN (dB) 05885-005 1 10 FREQUENCY (MHz) 100 Figure 7. Frequency Response at Various Temperatures Figure 10. Frequency Response Flatness at Various Temperatures Rev. A | Page 6 of 16 05885-008 05885-007 05885-006 ADA4430-1 9 6 3 0 –3 –6 –9 –12 –15 –18 –21 –24 –27 –30 –33 –36 –39 –42 –45 –48 65 60 2.0V p-p GROUP DELAY (ns) 55 50 VS = 5V 45 40 35 30 VS = 3V GAIN (dB) 0.2V p-p 05885-009 1 10 FREQUENCY (MHz) 100 1 10 FREQUENCY (MHz) 100 Figure 11. Frequency Response at Various Output Amplitudes –50 –55 –60 –65 –70 –75 –80 –85 –90 –95 –100 –105 –110 –115 –120 –125 –130 –135 –140 –145 –150 0 –5 –10 –15 –20 PSRR (dB) –25 –30 –35 –40 –45 –50 05885-010 Figure 14. Group Delay at Various Power Supplies NOISE SPECTRUM (NTSC) INPUT REFERRED BANDWIDTH 100kHz TO 5.0MHz AMPLITUDE (0dB = 714mV p-p) NOISE LEVEL = –76.8dB rms INPUT REFERRED 5V (dB) 3V –60 –65 0.001 0.01 0.1 1 10 0 1 2 3 FREQUENCY (MHz) 4 5 6 100 FREQUENCY (MHz) Figure 12. Input-Referred Noise Spectral Density –40 –50 –60 ISOLATION (dB) Figure 15. PSRR vs. Frequency at Various Power Supplies 10000 VDISABLE = 0V VIN = 1V p-p VDIS = 0V OUTPUT REFERRED –80 –90 –100 –110 05885-011 IMPEDANCE (Ω) –70 1000 100 –130 0.01 0.1 1 FREQUENCY (MHz) 10 100 10 0.1 1 10 FREQUENCY (MHz) 100 500 Figure 13. Input-to-Output Isolation—Disabled vs. Frequency Figure 16. Disabled Output Impedance vs. Frequency Rev. A | Page 7 of 16 05885-030 –120 05885-013 –55 05885-012 ADA4430-1 3.0 3.00 2.75 2.5 2.50 2.25 INPUT × 2 OUTPUT 3.0 2.5 2.0 1.5 1.0 0.5 0 ERROR –0.5 –1.0 –1.5 05885-018 OUTPUT VOLTAGE (V) 2.0 OUTPUT VOLTAGE (V) 2.00 1.75 1.50 1.25 1.00 0.75 0.50 50ns/DIV 1.5 1.0 0.5 100ns/DIV 0 05885-015 –2.0 –2.5 –3.0 0.25 0 Figure 17. Transient Response 3.5 3.0 2.5 DISABLE 3.0 2.5 3.5 Figure 20. Settling Time DISABLE OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) OUTPUT 2.0 1.5 1.0 0.5 05885-019 2.0 1.5 1.0 0.5 OUTPUT 1µs/DIV –0.5 05885-016 0 0 –0.5 500ns/DIV Figure 18. Disable Assert Time 4.0 Figure 21. Disable Deassert Time –0.10 DIFFERENCE BETWEEN VS AND VOUT (V) OUTPUT 2 × INPUT 3.5 3.0 2.5 –0.11 –0.12 –0.13 –0.14 –0.15 –0.16 –0.17 –0.18 –0.19 –0.20 –40 –25 –10 5 20 35 50 65 TEMPERATURE (°C) 80 95 110 05885-031 OUTPUT (V) 2.0 1.5 1.0 0.5 0 –0.5 –1.0 200ns/DIV 05885-033 125 Figure 19. Overdrive Recovery Figure 22. Output Swing Limits vs. Temperature Rev. A | Page 8 of 16 ERROR (%) ADA4430-1 1.85 POWER SUPPLY CURRENT–ENABLED (mA) 400 POWER SUPPLY CURRENT–DISABLED (nA) 2.0 1.8 POWER SUPPLY CURRENT (mA) ENABLED (V DIS = 3V) 1.6 1.4 1.80 300 +125°C +25°C –40°C 1.2 1.0 0.8 0.6 0.4 0.2 0 0 0.5 1.0 1.5 2.0 2.5 05885-022 1.75 200 1.70 DISABLED (VDIS = 0V) 1.65 –40 100 –20 0 20 40 60 80 100 120 0 05885-021 3.0 TEMPERATURE (°C) DISABLE VOLTAGE (V) Figure 23. Power Supply Current vs. Temperature Figure 24. Power Supply Current vs. Disable Voltage at Various Temperatures Rev. A | Page 9 of 16 ADA4430-1 TEST CIRCUITS VS+ 0.1µF 0.5V TEST GENERATOR 1 VIN 50Ω 50Ω 2 GND 3 SAG ×1 2.6kΩ 2.6kΩ 1.3kΩ 2.6kΩ 05885-038 ADA4430-1 5 PD 6 VS+ RL = 150Ω VOUT 4 118Ω 86.6Ω TEST RECEIVER 50Ω Figure 25. Test Circuit Used for Frequency Sweeps and Time-Domain Tests VS+ 0.1µF ADA4430-1 TEST GENERATOR 75Ω 1.0V 5 PD 6 VS+ RL = 150Ω TEST RECEIVER 220µF 150Ω 1 VIN ×1 2.6kΩ VOUT 4 75Ω 150Ω 2 GND 3 SAG 75Ω 2.6kΩ 1.3kΩ 2.6kΩ 05885-039 Figure 26. Test Circuit Used for Differential Gain, Differential Phase, and Noise Tests Rev. A | Page 10 of 16 ADA4430-1 THEORY OF OPERATION OVERVIEW The ADA4430-1 is designed for exceptional performance as both a filter and a low power driver for portable video applications. This performance is achieved by providing high order filtering without trading off power consumption or device size. While consuming only 1.85 mA quiescent supply current, the ADA4430-1 provides video output on a single-supply as low as 2.5 V. Such low power consumption and low supply operation would normally indicate a single op amp with a 2- or 3-pole roll-off; however, the ADA4430-1 achieves a sixth-order roll-off in addition to a 10 MΩ input impedance for easy clamping and lower DAC output power requirements. When not in use, the ADA44330-1 can be shutdown to draw less than 1 μA of supply current using the power-down pin, (PD). Additionally, the ADA4430-1 is unique in that it is a high order filter that fits into an SC70 package. The ADA4430-1 provides a minimum 1 dB bandwidth of 5.5 MHz and a minimum stop-band rejection of 42 dB at 27 MHz. Phase response is not sacrificed in spite of the exceptional filtering performance of the ADA4430-1, as exhibited by its group delay, which varies by only 7 ns from 100 kHz to 5 MHz. The ADA4430-1 is intended for use in applications that have both ac- and dc-coupled inputs and outputs. The rail-to-rail buffer on the ADA4430-1 output is able to drive 2 V p-p video signals into two doubly-terminated video loads (150 Ω each) on a single 2.5 V supply. The ADA4430-1 has a gain of 2 when the SAG correction pin is tied directly to the output, which makes up for the 6 dB termination loss. When the SAG feature is used (see Figure 29), the ADA4430-1 has a low frequency gain of 2.5 (≈ 8 dB) and a high frequency gain of 2. Signal offsets and supply levels must be considered when using the SAG correction feature to ensure that there are no headroom issues. The input range of the ADA4430-1 includes ground, while the output range is limited by the saturation of the output devices. Saturation occurs several tens of mV from the positive and negative supply rails. For accurate reproduction of groundreferenced input signals, an internal offset is used to shift the output up by 95 mV. The high input impedance and low input capacitance of the ADA4430-1 offer advantages in a number of low power applications. In reconstruction filter applications, the DAC can be placed in its lowest power mode, allowing the use of a largevalued load resistor. Using a large-valued load resistor does not interfere with the frequency response of the ADA4430-1. VIDEO DAC/ ENCODER The internal buffer at the ADA4430-1 input isolates the source resistance feeding the ADA4430-1 from the internal filter networks. High input impedance is also advantageous when using video clamping circuits. The output buffer feedback network used to create a gain of 2 is connected internally to the GND pin and has a nominal impedance of 5.2 kΩ. The current required to drive this feedback network causes the overall supply current to vary based on the output level. The feedback impedance was chosen specifically to minimize excess current consumption while maintaining optimal frequency behavior. POWER SAVINGS USING THE ADA4430-1 Using a series source termination and a shunt load termination on a low supply voltage with the ADA4430-1 realizes significant power savings compared with driving a video cable directly from a DAC output. Figure 27 shows a video DAC driving a cable directly. Properly terminating the line results in the DAC driving two 75 Ω loads and requires in excess of 30 mA to reach a fullscale level of 1.3 V. Figure 28 shows the same video load being driven using the ADA4430-1 and a series-shunt termination. This requires two times the output voltage to drive the equivalent of 150 Ω but only requires a little more than 15 mA to reach a fullscale output. When running on the same supply voltage as the DAC, this results in nearly a factor of two reduction in power compared with the circuit in Figure 27. The high level of filtering provided by the ADA4430-1 lowers the requirements on the DAC oversampling ratio, realizing further power savings. On any given DAC, 8× and 16× oversampling ratios can require twice the power consumption of a 4× oversampling ratio. 3V VIDEO DAC/ ENCODER 75Ω 75Ω 05885-034 Figure 27. DAC Driving Video Cable Directly 3V 0.1µF ADA4430-1 RL FILTER G = +2 75Ω 75Ω Figure 28. DAC Driving Video Cable Using the ADA4430-1 Rev. A | Page 11 of 16 05885-035 ADA4430-1 APPLICATIONS EXAMPLES ILLUSTRATING OUTPUT COUPLING The ADA4430-1 is ideally suited for use as a reconstruction filter that follows a video DAC or encoder. The application circuits in Figure 29, Figure 30, and Figure 31 illustrate a number of ways the ADA4430-1 can be used with a singlesupply current-output DAC on its input and its output ac- and dc-coupled. SAG correction allows the use of two small, lower cost capacitors in place of one large capacitor in applications with ac-coupled outputs. Circuits with ac-coupled outputs consume less power than those with dc-coupled outputs. 3V POWER-DOWN CONTROL 0.1µF ADA4430-1 VIDEO DAC/ENCODER 5 PD 6 VS+ VOUT 4 47µF 1 VIN RL 2 GND ×1 75Ω VIDEO OUT 2.6kΩ 1.3kΩ 2.6kΩ 05885-027 3 SAG 2.6kΩ 22µF Figure 29. AC-Coupled Output with SAG Correction 3V POWER-DOWN CONTROL 0.1µF ADA4430-1 VIDEO DAC/ENCODER 5 PD 6 VS+ VOUT 4 220µF 75Ω 1 VIN RL 2 GND ×1 VIDEO OUT 2.6kΩ 1.3kΩ 2.6kΩ 05885-028 3 SAG 2.6kΩ Figure 30. Traditional AC-Coupled Output with 220 μF Coupling Capacitor 3V POWER-DOWN CONTROL 0.1µF ADA4430-1 VIDEO DAC/ENCODER 5 PD 6 VS+ VOUT 4 75Ω 1 VIN RL 2 GND ×1 VIDEO OUT 2.6kΩ 1.3kΩ 2.6kΩ 05885-029 3 SAG 2.6kΩ Figure 31. DC-Coupled Output Rev. A | Page 12 of 16 ADA4430-1 USABLE INPUT VOLTAGE RANGE The output voltage range of the ADA4430-1 limits its usable input voltage range. The lower end of the input range is typically 0 V. The upper end of the usable input voltage range is calculated as VIN (max) = (VOM − VOO)/2 where: VIN (max) is the upper end of the usable input voltage range. VOM is the maximum output swing. VOO is the output-referred offset voltage. SAG CORRECTION FREQUENCY RESPONSE When using the SAG corrected circuit, the gain from the input to the immediate output of the ADA4430-1 is ×2.5 (≈8 dB) at extremely low frequencies where the outer feedback loop formed by the 22 μF capacitor effectively opens (see Figure 29) and exhibits a second-order peak of approximately 11 dB in the neighborhood of 5 Hz. This gain is approximately 7.5 dB at 30 Hz. The extra gain must be accounted for when considering low frequency input and output signal swings to keep them within their specified limits. The gain from the ADA4430-1 input to the load side of the 47 μF capacitor does not exhibit this behavior, rather it appears more like a single-pole highpass response. Figure 32 illustrates the SAG frequency response immediately at the ADA4430-1 output and at the load side of the 47 μF capacitor. 12 10 8 6 4 GAIN (dB) 2 0 –2 –4 –6 05885-040 –8 –10 AT ADA4430-1 OUTPUT AT LOAD SIDE OF 47µF CAPACITOR 1 10 100 1000 10000 100000 FREQUENCY (Hz) Figure 32. SAG Corrected Frequency Response at ADA4430-1 Output and at the Load Side of the 47 μF Capacitor Rev. A | Page 13 of 16 ADA4430-1 RECONSTRUCTION FILTER APPLICATIONS Figure 33 illustrates how to use the ADA4430-1 as a dc-coupled reconstruction filter with a pass band gain of 2 following the low power ADV7190/ADV7191 video encoder. One ADV7190/ ADV7191 output DAC is shown for illustrative purposes, and the remaining portions of the ADV7190/ADV7191 are omitted. The ADV7190/ADV7191 is operated in 4× oversampling mode. The 2.4 kΩ resistor, RSET, shown in Figure 33 sets the DAC output current to its minimum full-scale value of 2.16 mA, and the 600 Ω load resistor produces a full-scale voltage of 1.296 V at the ADA4430-1 input. Figure 34 illustrates another reconstruction filter application, following the ADV7174 video encoder. As in Figure 33, one ADV7174 output DAC is shown for illustrative purposes, and the remaining portions of the ADV7174 are omitted. The 1041 Ω resistor, RSET, shown in Figure 34, sets the DAC output current to its minimum full-scale value of 5 mA, and the 262.5 Ω load resistor produces a full-scale voltage of 1.313 V at the ADA4430-1 input. The ADV7174 can produce a maximum full-scale DAC output current of approximately 35 mA and is therefore capable of driving the video cable directly; however, as is shown in Figure 34, the ADA4430-1 offers a lower, power cable-driving option. Figure 34 reveals the details of how the ADA4430-1 saves power when driving video cables with terminations at both ends. A full-scale level at the DAC output produces 2.626 V at the ADA4430-1 output, which in turn delivers 17.5 mA into the cable. In the case shown in Figure 27, the output voltage is 1.313 V, but the current driven into the cable is 35 mA − twice that required when the ADA4430-1 is used. Therefore, the ADA4430-1 allows the video encoder to be operated at its minimum full-scale output current, and it efficiently handles the cable-driving burden. 3V POWER-DOWN CONTROL 0.1µF 0.1µF 17, 25, 29, 38, 43, 54, 63 VAA ADV7190/ADV7191 DAC AGND RSET 48 18, 24, 26, 33, 2.4kΩ 39, 42, 55, 64 1 VIN 600Ω 2 GND 3 SAG ×1 2.6kΩ 2.6kΩ 1.3kΩ 2.6kΩ 05885-036 ADA4430-1 5 PD 6 VS+ VOUT 4 75Ω 75Ω CABLE 75Ω Figure 33. Using the ADA4430-1 with the ADV7190/ADV7191 Video Encoder 3V POWER-DOWN CONTROL 0.1µF 0.1µF 2, 10, 18, 25, 27 VAA ADV7174 DAC RSET AGND 262.5Ω (191Ω + 71.5Ω) 31 6-9, 11, 12, 17, 19, 26, 40 1041Ω (931Ω + 110Ω) 1 VIN 2 GND 3 SAG ×1 ADA4430-1 56 PD VS+ VOUT 4 75Ω 75Ω CABLE 75Ω 2.6kΩ 2 .6kΩ 1.3kΩ 2.6kΩ Figure 34. Using the ADA4430-1 with the ADV7174 Video Encoder Rev. A | Page 14 of 16 05885-037 ADA4430-1 PRINTED CIRCUIT BOARD LAYOUT As with all high speed applications, attention to printed circuit board layout is of paramount importance. Standard high speed layout practices should be adhered to when designing with the ADA4430-1. A solid ground plane is recommended, and a 0.1 μF surface-mount, ceramic power supply, decoupling capacitor should be placed as close as possible to the supply pin. The GND pin should be connected to the ground plane with a trace that is as short as possible. Controlled impedance traces of the shortest length possible should be used to connect to the signal I/O pins and should not pass over any voids in the ground plane. A 75 Ω impedance level is typically used in video applications. All signal outputs of the ADA4430-1 should include series termination resistors when driving transmission lines. When the ADA4430-1 receives its inputs from a device with current outputs, the required load resistor value for the output current is most often different from the characteristic impedance of the signal traces. In this case, if the interconnections are sufficiently short (less than 2 inches), the trace does not have to be terminated in its characteristic impedance. Rev. A | Page 15 of 16 ADA4430-1 OUTLINE DIMENSIONS 2.20 2.00 1.80 2.40 2.10 1.80 1.35 1.25 1.15 PIN 1 1.30 BSC 1.00 0.90 0.70 6 1 5 2 4 3 0.65 BSC 1.10 0.80 0.40 0.10 0.46 0.36 0.26 0.10 MAX 0.30 0.15 0.10 COPLANARITY SEATING PLANE 0.22 0.08 COMPLIANT TO JEDEC STANDARDS MO-203-AB Figure 35. 6-Lead Thin Shrink Small Outline Transistor Package [SC70] (KS-6) Dimensions shown in millimeters ORDERING GUIDE Model ADA4430-1YKSZ_R2 1 ADA4430-1YKSZ-R71 ADA4430-1YKSZ-RL1 1 Temperature Range −40°C to +125°C −40°C to +125°C −40°C to +125°C Package Description 6-Lead SC70 6-Lead SC70 6-Lead SC70 Package Option KS-6 KS-6 KS-6 Branding H0G H0G H0G Ordering Quantity 250 3,000 10,000 Z = Pb-free part. ©2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D05885-0-6/06(A) Rev. A | Page 16 of 16