Single-Supply, High Speed, Triple Op Amp with Charge Pump ADA4858-3 CONNECTION DIAGRAM OUT1 –IN1 +IN1 NC ADA4858-3 16 15 14 13 12 +IN2 +VS 1 C1_b 3 11 –IN2 CHARGE PUMP 10 OUT2 CPO 4 6 7 8 OUT3 5 –IN3 9 PD NOTES 1. NC = NO CONNECT. 2. EXPOSED PAD, CONNECT TO GROUND. 07714-001 C1_a 2 +VS Integrated charge pump Supply range: 3 V to 5.5 V Output range: −3.3 V to −1.8 V 50 mA maximum output current for external use at −3 V High speed amplifiers −3 dB bandwidth: 600 MHz Slew rate: 600 V/μs 0.1 dB flatness: 85 MHz 0.1% settling time: 18 ns Low power Total quiescent current: 42 mA Power-down feature High input common-mode voltage range −1.8 V to +3.8 V at +5 V supply Current feedback architecture Differential gain error: 0.01% Differential phase error: 0.02° Available in 16-lead LFCSP +IN3 FEATURES Figure 1. APPLICATIONS Professional video Consumer video Imaging Active filters GENERAL DESCRIPTION The ADA4858-3 (triple) is a single-supply, high speed current feedback amplifier with an integrated charge pump that eliminates the need for negative supplies in order to output negative voltages or output a 0 V level for video applications. The 600 MHz −3 dB bandwidth and 600 V/μs slew rate make this amplifier well suited for many high speed applications. In addition, its 0.1 dB flatness out to 85 MHz at G = 2, along with its differential gain and phase errors of 0.01% and 0.02° into a 150 Ω load, make it well suited for professional and consumer video applications. This triple operational amplifier is designed to operate on supply voltages of 3.3 V to 5 V, using only 42 mA of total quiescent current, including the charge pump. To further reduce the power consumption, it is equipped with a powerdown feature that lowers the total supply current to as low as 2.5 mA when the amplifier is not being used. Even in powerdown mode, the charge pump can be used to power external components. The maximum output current for external use is 50 mA at −3 V. The amplifier also has a wide input commonmode voltage range that extends from 1.8 V below ground to 1.2 V below the positive rail at a 5 V supply. The ADA4858-3 is available in a 16-lead LFCSP, and it is designed to work over the extended industrial temperature range of −40°C to +105°C. Rev. 0 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 ©2008 Analog Devices, Inc. All rights reserved. ADA4858-3 TABLE OF CONTENTS Features .............................................................................................. 1 Overview ..................................................................................... 13 Applications ....................................................................................... 1 Charge Pump Operation ........................................................... 13 Connection Diagram ....................................................................... 1 Applications Information .............................................................. 14 General Description ......................................................................... 1 Gain Configurations .................................................................. 14 Revision History ............................................................................... 2 DC-Coupled Video Signal ........................................................ 14 Specifications..................................................................................... 3 Multiple Video Driver................................................................ 14 Absolute Maximum Ratings............................................................ 5 PD (Power-Down) Pin .............................................................. 15 Maximum Power Dissipation ..................................................... 5 Power Supply Bypassing ............................................................ 15 ESD Caution .................................................................................. 5 Layout .......................................................................................... 15 Pin Configuration and Function Descriptions ............................. 6 Outline Dimensions ....................................................................... 16 Typical Performance Characteristics ............................................. 7 Ordering Guide .......................................................................... 16 Theory of Operation ...................................................................... 13 REVISION HISTORY 10/08—Revision 0: Initial Version Rev. 0 | Page 2 of 16 ADA4858-3 SPECIFICATIONS TA = 25°C, VS = 5 V, G = 2, RF = 301 Ω, RF = 402 Ω for G = 1, RL = 150 Ω, unless otherwise noted. Table 1. Parameter DYNAMIC PERFORMANCE −3 dB Bandwidth Bandwidth for 0.1 dB Flatness Slew Rate Settling Time to 0.1% NOISE/DISTORTION PERFORMANCE Harmonic Distortion (HD2/HD3) Crosstalk Input Voltage Noise Input Current Noise Differential Gain Error Differential Phase Error DC PERFORMANCE Input Offset Voltage + nput Bias Current −Input Bias Current Open-Loop Transimpedance INPUT CHARACTERISTICS Input Resistance Input Capacitance Input Common-Mode Voltage Range Common-Mode Rejection Ratio OUTPUT CHARACTERISTICS Output Voltage Swing Output Overdrive Recovery Time Maximum Linear Output Current @ VO = 1 VPEAK POWER-DOWN Input Voltage Conditions Min Typ Max Unit VOUT = 0.1 V p-p, G = 1 VOUT = 0.1 V p-p VOUT = 2 V p-p, G = 1 VOUT = 2 V p-p VOUT = 2 V p-p VOUT = 2 V step VOUT = 2 V step 600 350 165 175 85 600 18 MHz MHz MHz MHz MHz V/μs ns fC = 1 MHz, VO = 2 V p-p fC = 5 MHz, VO = 2 V p-p f = 5 MHz f = 1 MHz f = 1 MHz (+IN/−IN) −86/−94 −71/−84 −60 4 2/9 0.01 0.02 dBc dBc dB nV/√Hz pA/√Hz % Degrees −14 −2 −13 300 +IN −IN +IN Typical +0.5 +0.7 +8 390 +14 +2 +13 15 90 1.5 −1.8 −61 −1.4 to +3.6 +3.8 −54 mV μA μA kΩ MΩ Ω pF V dB Rise/fall, f = 5 MHz fC = 1 MHz, HD2 ≤ −50 dBc −1.7 to +3.7 15 21 V ns mA Enabled Powered down 1.9 2 +0.1 V V μA μs μs 5.5 V Bias Current Turn-On Time Turn-Off Time POWER SUPPLY Operating Range Total Quiescent Current Amplifiers Charge Pump Total Quiescent Current When Powered Down Amplifiers Charge Pump Positive Power Supply Rejection Ratio Negative Power Supply Rejection Ratio Charge Pump Output Voltage Charge Pump Sink Current −0.1 0.3 1.6 3 15 19 23 21 mA mA 0.15 0.25 4 −64 −58 −3 0.3 mA mA dB dB V mA −3.3 Rev. 0 | Page 3 of 16 −60 −54 −2.5 150 ADA4858-3 TA = 25°C, VS = 3.3 V, G = 2, RF = 301 Ω, RF = 402 Ω for G = 1, RL = 150 Ω, unless otherwise noted. Table 2. Parameter DYNAMIC PERFORMANCE −3 dB Bandwidth Bandwidth for 0.1 dB Flatness Slew Rate Settling Time to 0.1% NOISE/DISTORTION PERFORMANCE Harmonic Distortion (HD2/HD3) Crosstalk Input Voltage Noise Input Current Noise Differential Gain Error Differential Phase Error DC PERFORMANCE Input Offset Voltage +Input Bias Current −Input Bias Current Open-Loop Transimpedance INPUT CHARACTERISTICS Input Resistance Input Capacitance Input Common-Mode Voltage Range Common-Mode Rejection Ratio OUTPUT CHARACTERISTICS Output Voltage Swing Output Overdrive Recovery Time Maximum Linear Output Current @ VO = 1 VPEAK POWER-DOWN Input Voltage Conditions Min Typ Max Unit VOUT = 0.1 V p-p, G = 1 VOUT = 0.1 V p-p VOUT = 2 V p-p, G = 1 VOUT = 2 V p-p VOUT = 2 V p-p VOUT = 2 V step VOUT = 2 V step 540 340 140 145 70 430 20 MHz MHz MHz MHz MHz V/μs ns fC = 1 MHz, VO = 2 V p-p fC = 5 MHz, VO = 2 V p-p f = 5 MHz f = 1 MHz f = 1 MHz (+IN/−IN) −88/−91 −75/−78 −60 4 2/9 0.02 0.03 dBc dBc dB nV/√Hz pA/√Hz % Degrees −14 −2 −13 300 +IN −IN +IN Typical +0.7 +0.6 +7 350 +14 +2 +13 15 90 1.5 −0.9 −60 −0.6 to +2.1 +2.2 −54 mV μA μA kΩ MΩ Ω pF V dB Rise/fall, f = 5 MHz fC = 1 MHz, HD2 ≤ −50 dBc −0.9 to +2.2 15 20 V ns mA Enabled Powered down 1.25 1.35 +0.1 V V μA μs μs 5.5 V Bias Current Turn-On Time Turn-Off Time POWER SUPPLY Operating Range Total Quiescent Current Amplifiers Charge Pump Total Quiescent Current When Powered Down Amplifiers Charge Pump Positive Power Supply Rejection Ratio Negative Power Supply Rejection Ratio Charge Pump Output Voltage Charge Pump Sink Current −0.1 0.3 1.6 3 14 19 21 20 mA mA 0.15 0.25 2 −63 −57 −2 0.3 mA mA dB dB V mA −2.1 Rev. 0 | Page 4 of 16 −60 −54 −1.8 45 ADA4858-3 ABSOLUTE MAXIMUM RATINGS MAXIMUM POWER DISSIPATION Table 3. See Figure 2 (−VS − 0.2 V) to (+VS − 1.2 V) ±VS Observe Power Derating Curves −65°C to +125°C −40°C to +105°C 300°C The maximum power that can be safely dissipated by the ADA4858-3 is limited by the associated rise in junction temperature. The maximum safe junction temperature for plastic encapsulated devices is determined by the glass transition temperature of the plastic, approximately 150°C. Temporarily exceeding this limit may cause a shift in parametric performance due to a change in the stresses exerted on the die by the package. Exceeding a junction temperature of 175°C for an extended period can result in device failure. To ensure proper operation, it is necessary to observe the maximum power derating curves in Figure 2. 2.5 Specification is for device in free air. 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. MAXIMUM POWER DISSIPATION (W) 1 Rating 6V 2.0 1.5 1.0 0.5 0 –40 –20 0 20 40 60 AMBIENT TEMPERATURE (°C) 80 100 07714-002 Parameter Supply Voltage Internal Power Dissipation1 16-Lead LFCSP Input Voltage (Common Mode) Differential Input Voltage Output Short-Circuit Duration Storage Temperature Range Operating Temperature Range Lead Temperature (Soldering, 10 sec) Figure 2. Maximum Power Dissipation vs. Temperature for ADA4858-3 ESD CAUTION Rev. 0 | Page 5 of 16 ADA4858-3 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS ADA4858-3 OUT1 –IN1 +IN1 NC TOP VIEW (Not to Scale) 16 15 14 13 12 +IN2 +VS 1 11 –IN2 CHARGE PUMP 10 OUT2 CPO 4 6 7 8 –IN3 OUT3 +VS 5 +IN3 9 PD NOTES 1. NC = NO CONNECT. 2. EXPOSED PAD, CONNECT TO GROUND. 07714-003 C1_a 2 C1_b 3 Figure 3. Pin Configuration. Table 4. Pin Function Descriptions Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 (EPAD) Mnemonic +VS C1_a C1_b CPO +VS +IN3 −IN3 OUT3 PD OUT2 −IN2 +IN2 NC +IN1 −IN1 OUT1 Exposed Pad (EPAD) Description Positive Supply for Charge Pump. Charge Pump Capacitor Side a. Charge Pump Capacitor Side b. Charge Pump Output. Positive Supply. Noninverting Input 3. Inverting Input 3. Output 3. Power Down. Output 2. Inverting Input 2. Noninverting Input 2. No Connect. Noninverting Input 1. Inverting Input 1. Output 1. The exposed pad must be connected to ground. Rev. 0 | Page 6 of 16 ADA4858-3 TYPICAL PERFORMANCE CHARACTERISTICS VS = 5 V, G = 2, RF = 301 Ω, RF = 402 Ω for G = 1, RF = 200 Ω for G = 5, RL = 150 Ω, large signal VOUT = 2 V p-p, small signal VOUT = 0.1 V p-p, and T = 25ºC, unless otherwise noted. 0 G=2 –1 –2 G=5 –3 –4 –5 –6 –7 –8 1 10 100 1000 FREQUENCY (MHz) G=1 1 0 –1 G=2 –2 G=5 –3 –4 –5 –6 –7 –8 1 NORMALIZED CLOSED-LOOP GAIN (dB) G=2 G=1 –1 –2 G=5 –3 –4 –5 –6 –7 –8 1 10 100 1000 FREQUENCY (MHz) VS = 3.3V 1 G=1 0 –1 G=2 –2 G=5 –3 –4 –5 –6 –7 –8 07714-005 1 100 1000 FREQUENCY (MHz) Figure 5. Small Signal Frequency Response vs. Gain Figure 8. Large Signal Frequency Response vs. Gain 2 1 RF = 301Ω 0 NORMALIZED CLOSED-LOOP GAIN (dB) 2 RF = 200Ω –1 RF = 402Ω –2 RF = 499Ω –3 –4 –5 –6 –7 –8 1 10 100 1000 FREQUENCY (MHz) 07714-006 NORMALIZED CLOSED-LOOP GAIN (dB) 10 Figure 6. Small Signal Frequency Response vs. Feedback Resistor 1 RF = 200Ω 0 RF = 301Ω –1 RF = 402Ω –2 RF = 499Ω –3 –4 –5 –6 –7 –8 1 10 100 1000 FREQUENCY (MHz) Figure 9. Large Signal Frequency Response vs. Feedback Resistor Rev. 0 | Page 7 of 16 07714-009 NORMALIZED CLOSED-LOOP GAIN (dB) 2 0 1000 Figure 7. Large Signal Frequency Response vs. Gain VS = 3.3V 1 100 FREQUENCY (MHz) Figure 4. Small Signal Frequency Response vs. Gain 2 10 07714-007 G=1 07714-008 1 NORMALIZED CLOSED-LOOP GAIN (dB) 2 07714-004 NORMALIZED CLOSED-LOOP GAIN (dB) 2 0.2 0.1 0.1 –0.1 –0.2 VS = 3.3V –0.3 –0.4 –0.5 –0.6 –0.7 –0.8 1 10 100 1000 FREQUENCY (MHz) –0.1 RF = 301Ω –0.2 –0.3 –0.4 –0.5 –0.6 –0.7 –0.8 1 0 –10 –20 –20 –30 –30 DISTORTION (dBc) 0 –40 –50 HD2 –70 HD3 –80 –50 –60 HD2 –70 HD3 –80 –90 –100 100 FREQUENCY (MHz) 07714-011 –90 10 1000 –40 –100 1 100 Figure 13. Large Signal 0.1 dB Flatness vs. Feedback Resistor –10 –60 10 FREQUENCY (MHz) Figure 10. Large Signal 0.1 dB Flatness vs. Supply Voltage DISTORTION (dBc) 0 07714-013 VS = 5V RF = 200Ω 1 100 10 FREQUENCY (MHz) Figure 11. Harmonic Distortion vs. Frequency 07714-014 0 NORMALIZED CLOSED-LOOP GAIN (dB) 0.2 07714-010 NORMALIZED CLOSED-LOOP GAIN (dB) ADA4858-3 Figure 14. Harmonic Distortion vs. Frequency, VS = 3.3 V 10 –10 0 –20 –30 CMRR (dB) –20 –30 –40 –40 –50 –50 –70 0.1 1 10 100 400 FREQUENCY (MHz) Figure 12. Power Supply Rejection Ratio (PSRR) vs. Frequency –70 0.1 1 10 100 400 FREQUENCY (MHz) Figure 15. Common-Mode Rejection Ratio (CMRR) vs. Frequency Rev. 0 | Page 8 of 16 07714-015 –60 –60 07714-012 PSRR (dB) –10 –20 –40 –30 –50 –40 CROSSTALK (dB) –30 –70 –50 –60 –80 –70 –90 –80 10 100 400 FREQUENCY (MHz) –90 0.1 1 Figure 16. Forward Isolation vs. Frequency VOUT = 200mV p-p OUTPUT VOLTAGE, VS = 5V (V) OUTPUT VOLTAGE (V) 0.05 0 –0.05 VS = 5V –0.10 1.5 2.0 1.0 1.5 0.5 1.0 0 0.5 07714-017 VS = 3.3V TIME (5ns/DIV) VS = 3.3V –0.5 –1.0 –1.0 –1.5 TIME (5ns/DIV) Figure 20. Large Signal Transient Response vs. Supply Voltage Figure 17. Small Signal Transient Response vs. Supply Voltage 1.5 G=1 VOUT = 200mV p-p CL = 4pF C = 10pF L 1.0 OUTPUT VOLTAGE (V) 0.10 0.05 0 –0.05 CL = 4pF CL = 6pF 0.5 0 –0.5 –1.0 –0.10 CL = 10pF CL = 6pF TIME (5ns/DIV) 07714-018 OUTPUT VOLTAGE (V) 0 –0.5 VS = 5V –0.15 –0.15 400 Figure 19. Crosstalk vs. Frequency 0.10 0.15 100 07714-020 0.15 10 FREQUENCY (MHz) OUTPUT VOLTAGE, VS = 3.3V (V) 1 –1.5 G=1 TIME (5ns/DIV) Figure 21. Large Signal Transient Response vs. Capacitive Load Figure 18. Small Signal Transient Response vs. Capacitive Load Rev. 0 | Page 9 of 16 07714-021 –100 0.1 07714-019 –60 07714-016 FORWARD ISOLATION (dB) ADA4858-3 ADA4858-3 1.5 CL = 10pF CL = 16pF 1.0 CL = 4pF CL = 14pF OUTPUT VOLTAGE (V) 0.05 0 –0.05 0.5 0 –0.5 –0.10 –1.0 07714-022 VOUT = 200mV p-p –0.15 TIME (5ns/DIV) –1.5 TIME (5ns/DIV) Figure 22. Small Signal Transient Response vs. Capacitive Load 2.0 1.6 OUTPUT 0.5 2.0 0.5 0.4 1.6 0.4 0.3 1.2 0.2 INPUT 0.4 0.1 0 0 –0.4 –0.1 ERROR 0.3 ERROR 0.8 AMPLITUDE (V) 0.8 Figure 25. Large Signal Transient Response vs. Capacitive Load ERROR (%) 1.2 07714-025 OUTPUT VOLTAGE (V) 0.10 AMPLITUDE (V) CL = 10pF CL = 6pF 0.2 0.1 0.4 0 0 –0.1 –0.4 –0.8 –0.2 –0.8 –1.2 –0.3 –1.2 –1.6 –0.4 –1.6 ERROR (%) 0.15 –0.2 INPUT –0.3 OUTPUT 15 20 25 30 35 –0.5 40 –2.0 –5 TIME (ns) 0 5 3.0 25 30 35 VIN VS = 3.3V 1 0.5 0 0 –1 –0.5 –2 –1.0 –3 –1.5 OUTPUT VOLTAGE (V) 1.0 INPUT VOLTAGE (V) 2 1.5 VOUT 0.5 1.0 0.5 0 0 –0.5 –0.5 –1.0 TIME (20ns/DIV) –1.5 07714-024 OUTPUT VOLTAGE (V) 1.5 VOUT 1.5 1.0 2.0 3 –0.5 40 2.5 2.0 4 20 Figure 26. Settling Time (Fall) 2.5 VIN 15 TIME (ns) Figure 23. Settling Time (Rise) 5 10 –1.0 –2.0 Figure 24. Output Overdrive Recovery TIME (20ns/DIV) Figure 27. Output Overdrive Recovery, VS = 3.3 V Rev. 0 | Page 10 of 16 07714-027 10 07714-026 5 INPUT VOLTAGE (V) 0 07714-023 –2.0 –5 –0.4 ADA4858-3 1000 1000 RISE, G = 2 RISE, G = 1 800 FALL, G = 2 600 FALL, G = 1 400 300 500 200 100 2.5 0 0 Figure 28. Slew Rate vs. Output Voltage 20 18 –1.6 16 –2.0 14 –2.4 12 OUTPUT VOLTAGE –3.2 2.5 3.0 3.5 4.0 10 4.5 5 VOUT 8 5.0 CHARGE PUMP SUPPLY VOLTAGE (V) 0.5 4 0 3 –0.5 2 –1.0 1 0 –1.5 07714-029 –2.8 VPD OUTPUT VOLTAGE (V) –0.8 AMPLIFIER CURRENT TIME (400ns/DIV) Figure 29. Charge Pump Output Voltage and Current vs. Supply Voltage Figure 32. Enable/Power Down Time 100 18 90 INPUT CURRENT NOISE (pA/ Hz) 20 16 14 12 10 8 6 4 2 80 70 60 50 40 30 20 –IN 10 1k 10k 100k FREQUENCY (Hz) 1M 07714-030 0 100 2.5 6 1.0 CURRENT (mA) 22 –1.2 2.0 1.5 24 CHARGE PUMP CURRENT 1.0 1.5 OUTPUT VOLTAGE (V p-p) Figure 31. Slew Rate vs. Output Voltage –0.4 INPUT VOLTAGE NOISE (nV/ Hz) CHARGE PUMP OUTPUT VOLTAGE (V) 0 0.5 POWER DOWN VOLTAGE (V) 2.0 07714-028 1.0 1.5 OUTPUT VOLTAGE (V p-p) FALL, G = 1 300 100 0.5 FALL, G = 2 400 200 0 RISE, G = 1 600 07714-032 500 RISE, G = 2 700 07714-031 SLEW RATE (V/µs) SLEW RATE (V/µs) 700 Figure 30. Input Voltage Noise vs. Frequency 0 100 +IN 1k 10k 100k FREQUENCY (Hz) Figure 33. Input Current Noise vs. Frequency Rev. 0 | Page 11 of 16 1M 07714-033 800 0 VS = 3.3V 900 900 ADA4858-3 –100 –110 –110 –115 –115 POWER (dBm) –105 –120 –125 –130 –120 –125 –130 –135 –135 –140 –140 –145 –145 –150 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 VS = 3.3V CHARGE PUMP HARMONICS –105 4.0 FREQUENCY (MHz) 4.5 5.0 07714-201 POWER (dBm) CHARGE PUMP HARMONICS Figure 34. Output Spectrum vs. Frequency –150 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 FREQUENCY (MHz) Figure 35. Output Spectrum vs. Frequency Rev. 0 | Page 12 of 16 4.5 5.0 07714-202 –100 ADA4858-3 THEORY OF OPERATION OVERVIEW Φ1 +VS CHARGE PUMP OPERATION The on-board charge pump creates a negative supply for the amplifier. It provides different negative voltages depending on the power supply voltage. For a +5 V supply, the negative supply generated is equal to −3 V with 150 mA of output supply current, and for a +3.3 V supply, the negative supply is equal to −2 V with 45 mA of output supply current. Figure 36 shows the charging cycle when the supply voltage +VS charges C1 through Φ1 to ground. During this cycle, C1 quickly charges to reach the +VS voltage. The discharge cycle then begins with switching Φ1 off and switching Φ2 on, as shown in Figure 37. When C1 = C2, the charge in C1 is divided between the two capacitors and slowly increases the voltage in C2 until it reaches a predetermined voltage (−3 V for +5 V supply and −2 V for +3.3 V supply). The typical charge pump charging and discharging frequency is 550 kHz with a 150 Ω load and no input signal. This frequency changes with the load current, and it can reach the dc level if the amplifier is powered down. CPO b C2 Φ1 07714-137 C1 The ADA4858-3 is a current feedback amplifier designed for exceptional performance as a triple amplifier with a variable gain capability. Its specifications make it especially suitable for SD and HD video applications. The ADA4858-3 provides HD video output on a single supply as low as 3.0 V while only consuming 13 mA per amplifier. It also features a power-down pin (PD) that reduces the quiescent current to 2 mA when activated. Figure 36. C1 Charging Cycle a +VS Φ2 C1 CPO C2 Φ2 b 07714-138 The ADA4858-3 can be used in applications that require both ac- and dc-coupled inputs and outputs. The output stage on the ADA4858-3 is capable of driving 2 V p-p video signals into two doubly terminated video loads (150 Ω each) on a single 5 V supply. The input range of the ADA4858-3 includes ground, while the output range is limited by the output headroom set by the voltage drop across the two diodes from each rail, which occurs 1.2 V from the positive and negative supply rails. a Figure 37. C1 Discharging Cycle The ADA4858-3 specifications make it especially suitable for SD and HD video applications. It also allows dc-coupled video signals with its black level set to 0 V and its sync tip at −300 mV for YPbPr video. The charge pump is always on, even when the power-down pin (PD) is enabled and the amplifier is off. However, if a negative current is not used, it is in an idle state. Each amplifier needs −6.3 mA of current, which totals −19 mA for all three amplifiers. This means additional negative current may be available by the charge pump for external use. Pin 4 (CPO) is the charge pump output, which provides access to the negative supply generated by the charge pump. Placing a 1 μF charge capacitor at the CPO pin is essential to hold the charge. If the negative supply is used to power another device in the system, it is only possible for the 5 V supply operation. In the 3.3 V supply operation, the charge pump output current is very limited. The capacitor at the CPO pin, which regulates the ripple of the negative voltage, can be used as a coupling capacitor for the external device. However, the charge pump current should be limited to a maximum of 50 mA for external use. When powering down the ADA4858-3, the charge pump is not affected and its output voltage and current is still available for external use. Rev. 0 | Page 13 of 16 ADA4858-3 APPLICATIONS INFORMATION GAIN CONFIGURATIONS The ADA4858-3 is a single-supply, high speed, voltage feedback amplifier. Table 5 provides a convenient reference for quickly determining the feedback and gain set resistor values and bandwidth for common gain configurations. The choice of RF and RG should be carefully considered for maximum flatness vs. power dissipation trade-off. In this case, the flatness is over 90 MHz, which is more than the high definition video requirement. 5V C1 10µF C2 0.1µF Table 5. Recommended Values and Frequency Performance1 1 RF (Ω) 402 249 200 Small Signal −3 dB BW (MHz) 600 450 160 RG (Ω) N/A 249 40 Large Signal 0.1 dB Flatness (MHz) 88 95 35 VIN + R1 75Ω Figure 38 and Figure 39 show the typical noninverting and inverting configurations and the recommended bypass capacitor values. R3 249Ω R2 249Ω 10µF VOUT R5 75Ω – Conditions: VS = 5 V, TA = 25°C, RL = 150 Ω. +VS R4 75Ω U1 ADA4858-3 07714-141 Gain 1 2 5 –VS Figure 40. DC-Coupled, Single-Supply Schematic MULTIPLE VIDEO DRIVER + ADA4858-3 In applications requiring that multiple video loads be driven simultaneously, the ADA4858-3 can deliver 5 V supply operation. Figure 41 shows the ADA4858-3 configured with two video loads, and Figure 42 shows the two video load performances. VOUT – RF 249Ω RG +VS Figure 38. Noninverting Gain Configuration RF +VS RG 249Ω 10µF 75Ω CABLE VIN RG – VIN 0.1µF ADA4858-3 10µF 0.1µF – 75Ω ADA4858-3 75Ω CABLE VOUT1 75Ω + 75Ω 75Ω CABLE 75Ω VOUT VOUT2 75Ω + 07714-142 07714-139 RF 07714-140 Figure 41. Video Driver Schematic for Two Video Loads 6.5 Figure 39. Inverting Gain Configuration RL = 150Ω 6.0 The ADA4858-3 does not have a rail-to-rail output stage. The output can be within 1 V of the rails. Having a charge pump on-board that can provide −3 V on a +5 V supply and −2 V on +3.3 V supply makes this part excellent for video applications. In dc-coupled applications, the black color has a 0 V voltage reference. This means that the output voltage should be able to reach 0 V, which is feasible with the presence of the charge pump. Figure 40 shows the schematic of a dc-coupled, single-supply application. It is similar to dual-supply application, where the input is properly terminated with a 50 Ω resistor to ground. The amplifier itself is set at a gain of 2 to account for the input termination loss. CLOSED-LOOP GAIN (dB) DC-COUPLED VIDEO SIGNAL Rev. 0 | Page 14 of 16 5.5 RL = 75Ω 5.0 4.5 4.0 3.5 VS = 5V RF = 301Ω G=2 VOUT = 2V p-p 3.0 2.5 1 10 100 1000 FREQUENCY (MHz) Figure 42. Large Signal Frequency Response for Various Loads 07714-040 VIN 0.1µF ADA4858-3 PD (POWER-DOWN) PIN LAYOUT The ADA4858-3 is equipped with a PD (power-down) pin for all three amplifiers. This allows the user the ability to reduce the quiescent supply current when an amplifier is not active. The power-down threshold levels are derived from ground level. The amplifiers are powered down when the voltage applied to the PD pin is greater than a certain voltage from ground. In a 5 V supply application, the voltage is greater than 2 V, and in a 3.3 V supply application, the voltage is greater than 1.5 V. The amplifier is enabled whenever the PD pin is left floating (not connected). If the PD pin is not used, it is best to leave it floating or connected to ground. Note that the power-down feature does not control the charge pump output voltage and current. As is the case with all high speed applications, careful attention to printed circuit board (PCB) layout details prevents associated board parasitics from becoming problematic. The ADA4858-3 can operate at up to 600 MHz; therefore, proper RF design techniques must be employed. The PCB should have a ground plane covering all unused portions of the component side of the board to provide a low impedance return path. Removing the ground plane on all layers from the area near and under the input and output pins reduces stray capacitance. Signal lines connecting the feedback and gain resistors should be kept as short as possible to minimize the inductance and stray capacitance associated with these traces. Termination resistors and loads should be located as close as possible to their respective inputs and outputs. Input and output traces should be kept as far apart as possible to minimize coupling (crosstalk) through the board. Adherence to microstrip or stripline design techniques for long signal traces (greater than 1 inch) is recommended. For more information on high speed board layout, see “A Practical Guide to High-Speed Printed-Circuit-Board Layout”, Analog Dialogue, Volume 39, Number 3, September 2005 at www.analog.com. Table 6. Power-Down Voltage Control PD Pin Not Active Active 5V <1.5 V >2 V 3.3 V <1 V >1.5 V POWER SUPPLY BYPASSING Careful attention must be paid to bypassing the power supply pins of the ADA4858-3. High quality capacitors with low equivalent series resistance (ESR), such as multilayer ceramic capacitors (MLCCs), should be used to minimize supply voltage ripple and power dissipation. A large, usually tantalum, capacitor between 2.2 μF to 47 μF located in proximity to the ADA4858-3 is required to provide good decoupling for lower frequency signals. The actual value is determined by the circuit transient and frequency requirements. In addition, 0.1 μF MLCC decoupling capacitors should be located as close to each of the power supply pins and across from both supplies as is physically possible, no more than 1/8-inch away. The ground returns should terminate immediately into the ground plane. Locating the bypass capacitor return close to the load return minimizes ground loops and improves performance. Rev. 0 | Page 15 of 16 ADA4858-3 OUTLINE DIMENSIONS 4.00 BSC SQ 12° MAX 1.00 0.85 0.80 0.65 BSC TOP VIEW 3.75 BSC SQ 0.75 0.60 0.50 0.80 MAX 0.65 TYP SEATING PLANE 16 13 12 9 PIN 1 INDICATOR 1 2.25 2.10 SQ 1.95 8 5 4 0.25 MIN 1.95 BSC 0.05 MAX 0.02 NOM 0.35 0.30 0.25 (BOTTOM VIEW) 0.20 REF COPLANARITY 0.08 FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET. COMPLIANT TO JEDEC STANDARDS MO-220-VGGC 072808-A PIN 1 INDICATOR 0.60 MAX 0.60 MAX Figure 43.16-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 4 mm × 4 mm Body, Very Thin Quad (CP-16-4) Dimensions shown in millimeters ORDERING GUIDE Model ADA4858-3ACPZ-R2 1 ADA4858-3ACPZ-R71 ADA4858-3ACPZ-RL1 1 Temperature Range –40°C to +105°C –40°C to +105°C –40°C to +105°C Package Description 16-Lead LFCSP_VQ 16-Lead LFCSP_VQ 16-Lead LFCSP_VQ Z = RoHS Compliant Part. ©2008 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D07714-0-10/08(0) Rev. 0 | Page 16 of 16 Package Option CP-16-4 CP-16-4 CP-16-4 Ordering Quantity 250 1,500 5,000