Single Supply, High Speed, Rail-to-Rail Output, Triple Op Amp ADA4855-3 NC 3 PD 4 –IN1 –VS +IN1 13 12 +VS 11 OUT2 ADA4855-3 10 –IN2 9 +IN3 5 6 7 8 +VS NOTES 1. NC = NO CONNECT. 2. EXPOSED PAD CONNECTED TO –VS. 07685-001 2 15 14 –VS 1 16 OUT3 NC +IN2 OUT1 CONNECTION DIAGRAM Voltage feedback architecture Rail-to-rail output swing: 0.1 V to 4.9 V High speed amplifiers 410 MHz, −3 dB bandwidth, G = 1 210 MHz, −3 dB bandwidth, G = 2 Slew rate: 870 V/μs 53 MHz, 0.1 dB large signal flatness 5.3 ns settling time to 0.1% with 2 V step High input common-mode voltage range −VS − 0.2 V to +VS − 1 V Supply range: 3 V to 5.5 V Differential gain error: 0.01% Differential phase error: 0.01° Low power 7.8 mA/amplifier typical supply current Power-down feature Available in 16-lead LFCSP –IN3 FEATURES Figure 1. APPLICATIONS Professional video Consumer video Imaging Instrumentation Base stations Active filters 1 The ADA4855-3 offers a typical low power of 7.8 mA per amplifier and is capable of delivering up to 57 mA of load current. It also features a power-down function for power sensitive applications that reduces the supply current down to 1 mA. The ADA4855-3 is available in a 16-lead LFCSP and is designed to work over the extended industrial temperature range of −40°C to +105°C. 0 G=1 –1 G=2 G=5 –2 –3 –4 –5 –6 1 100 10 FREQUENCY (MHz) 1000 07685-004 The ADA4855-3 (triple) is a single-supply, rail-to-rail output operational amplifier. It provides excellent high speed performance with 410 MHz, −3 dB bandwidth and a slew rate of 870 V/μs. It has a wide input common-mode voltage range that extends from 0.2 V below ground to 1 V below the positive rail.In addition, the output voltage swings within 100 mV of either supply rail, making this rail-to-rail operational amplifier easy to use on singlesupply voltages as low as 3.3 V. NORMALIZED CLOSED-LOOP GAIN (dB) GENERAL DESCRIPTION Figure 2. Frequency Response 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. ADA4855-3 TABLE OF CONTENTS Features .............................................................................................. 1 Theory of Operation ...................................................................... 14 Applications ....................................................................................... 1 Applications Information .............................................................. 15 Connection Diagram ....................................................................... 1 Gain Configurations .................................................................. 15 General Description ......................................................................... 1 20 MHz Active Low-Pass Filter ................................................ 15 Revision History ............................................................................... 2 RGB Video Driver ...................................................................... 16 Specifications..................................................................................... 3 Driving Multiple Video Loads .................................................. 16 5 V Operation ............................................................................... 3 PD (Power-Down) Pin .............................................................. 16 3.3 V Operation ............................................................................ 4 Single-Supply Operation ........................................................... 17 Absolute Maximum Ratings............................................................ 5 Power Supply Bypassing ............................................................ 17 Thermal Resistance ...................................................................... 5 Layout .......................................................................................... 17 Maximum Power Dissipation ..................................................... 5 Outline Dimensions ....................................................................... 18 ESD Caution .................................................................................. 5 Ordering Guide .......................................................................... 18 Pin Configuration and Function Descriptions ............................. 6 Typical Performance Characteristics ............................................. 7 Test Circuits ..................................................................................... 13 REVISION HISTORY 11/08—Revision 0: Initial Version Rev. 0 | Page 2 of 20 ADA4855-3 SPECIFICATIONS 5 V OPERATION TA = 25°C, VS = 5 V, 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, Output to Output Input Voltage Noise Input Current Noise Differential Gain Error Differential Phase Error DC PERFORMANCE Input Offset Voltage Input Offset Voltage Drift Input Bias Current Input Offset Current Open-Loop Gain INPUT CHARACTERISTICS Input Resistance Input Capacitance Input Common-Mode Voltage Range Common-Mode Rejection Ratio OUTPUT CHARACTERISTICS Output Voltage Swing Linear Output Current per Amplifier POWER-DOWN Turn-On Time Turn-Off Time Bias Current Turn-On Voltage POWER SUPPLY Operating Range Quiescent Current per Amplifier Supply Current When Powered Down Power Supply Rejection Ratio Test Conditions Min Typ Max Unit VO = 0.1 V p-p VO = 2 V p-p VO = 0.1 V p-p, G = 2 VO = 2 V p-p, G = 2 VO = 2 V p-p VO = 2 V p-p, G = 2 VO = 2 V step VO = 2 V step (rise/fall) VO = 2 V step (rise/fall), G = 2 410 200 210 120 53 50 870 5.3/9.5 7.4/7 MHz MHz MHz MHz MHz MHz V/μs ns ns fC = 5 MHz, VO = 2 V p-p, RL = 1 kΩ fC = 20 MHz, VO = 2 V p-p, RL = 1 kΩ f = 5 MHz, G = 2 f = 100 kHz f = 100 kHz G=2 G=2 −84/−105 −60/−66 −90 6.8 2 0.01 0.01 dBc dBc dBc nV/√Hz pA/√Hz % Degrees VO = 0.5 V to 4.5 V 1.3 5.5 −3.8 ±0.05 92 3 6.4 0.5 mV μV/°C μA μA dB VCM = –0.2 V to +4 V 94 MΩ pF V dB HD2 ≤ −60 dBc, RL = 10 Ω 0.1 to 4.9 57 V mA 78 1.2 0.3 −125 +VS − 1.25 ns μs μA μA V −VS − 0.2 On Off +VS − 1 3 ∆VS = 4.5 V to 5.5 V Rev. 0 | Page 3 of 20 5.5 7.8 1.1 96 V mA mA dB ADA4855-3 3.3 V OPERATION TA = 25°C, VS = 3.3 V, 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, Output to Output Input Voltage Noise Input Current Noise Differential Gain Error Differential Phase Error DC PERFORMANCE Input Offset Voltage Input Offset Voltage Drift Input Bias Current Input Offset Current Open-Loop Gain INPUT CHARACTERISTICS Input Resistance Input Capacitance Input Common-Mode Voltage Range Common-Mode Rejection Ratio OUTPUT CHARACTERISTICS Output Voltage Swing Linear Output Current per Amplifier POWER-DOWN Turn-On Time Turn-Off Time Turn-On Voltage POWER SUPPLY Operating Range Quiescent Current per Amplifier Supply Current When Powered Down Power Supply Rejection Ratio Test Conditions Min Typ Max Unit VO = 0.1 V p-p VO = 1.4 V p-p VO = 0.1 V p-p, G = 2 VO = 2 V p-p, G = 2 VO = 1.4 V p-p, G = 2 VO = 2 V step, G = 2 VO = 2 V step (rise/fall), G = 2 430 210 210 125 55 870 7.4/7.1 MHz MHz MHz MHz MHz V/μs ns fC = 5 MHz, VO = 2 V p-p, RL = 1 kΩ fC = 20 MHz, VO = 2 V p-p, RL = 1 kΩ f = 5 MHz, G = 2 f = 100 kHz f = 100 kHz G=2 G=2 −76/−76 −68/−75 −88 6.8 2 0.01 0.01 dBc dBc dBc nV/√Hz pA/√Hz % Degrees VO = 0.5 V to 4.5 V 1.3 5.5 −3.8 0.05 92 mV μV/°C μA μA dB 6.4 0.5 VCM = –0.2 V to +3.2 V 94 MΩ pF V dB HD2 ≤ −60 dBc, RL = 10 Ω 0.1 to 3.22 40 V mA 78 1.2 +VS − 1.25 ns μs V −VS − 0.2 +VS − 1 3 ∆VS = 2.97 V to 3.63 V Rev. 0 | Page 4 of 20 5.5 7.5 0.95 94 V mA mA dB ADA4855-3 ABSOLUTE MAXIMUM RATINGS MAXIMUM POWER DISSIPATION 1 Rating 6V See Figure 3 (−VS − 0.2 V) to (+VS − 1 V) ±VS Observe power curves −65°C to +125°C −40°C to +105°C 300°C 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. The maximum power that can be safely dissipated by the ADA4855-3 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. 3.0 THERMAL RESISTANCE θJA is specified for the worst-case conditions, that is, θJA is specified for a device soldered in a circuit board for surface-mount packages. 2.5 2.0 1.5 1.0 0.5 07685-103 Parameter Supply Voltage Internal Power Dissipation1 Common-Mode Input Voltage Differential Input Voltage Output Short-Circuit Duration Storage Temperature Range Operating Temperature Range Lead Temperature (Soldering, 10 sec) MAXIMUM POWER DISSIPATION (W) Table 3. 90 100 80 70 60 50 40 30 20 0 10 0 Unit °C/W –10 θJC 17.5 –20 θJA 67 –40 Package Type 16-Lead LFCSP –30 Table 4. AMBIENT TEMPERATURE (°C) Figure 3. Maximum Power Dissipation vs. Ambient Temperature ESD CAUTION Rev. 0 | Page 5 of 20 ADA4855-3 14 OUT1 13 –VS 15 –IN1 16 +IN1 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS NC 1 10 –IN2 9 +VS NOTES 1. NC = NO CONNECT. 2. EXPOSED PAD CONNECTED TO –VS. 07685-003 –VS 8 +IN3 5 PD 4 11 OUT2 TOP VIEW (Not to Scale) OUT3 7 NC 3 12 +VS ADA4855-3 –IN3 6 +IN2 2 Figure 4. Pin Configuration Table 5. Pin Function Descriptions Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 (EPAD) Mnemonic NC +IN2 NC PD +IN3 −IN3 OUT3 −VS +VS −IN2 OUT2 +VS −VS OUT1 −IN1 +IN1 Exposed Pad (EPAD) Description No Connect. Noninverting Input 2. No Connect. Power Down. Noninverting Input 3. Inverting Input 3. Output 3. Negative Supply. Positive Supply. Inverting Input 2. Output 2. Positive Supply. Negative Supply. Output 1. Inverting Input 1. Noninverting Input 1. The exposed pad must be connected to −VS. Rev. 0 | Page 6 of 20 ADA4855-3 TYPICAL PERFORMANCE CHARACTERISTICS T = 25°C, VS = 5V, G = 1, RF = 1 kΩ for G > 1, RL = 150 Ω, small signal VOUT = 100 mV p-p, and large signal VOUT = 2 V p-p, unless otherwise noted. 0 G=1 –1 G=2 G=5 –3 –4 –5 –6 1 10 100 FREQUENCY (MHz) 1000 G=1 G=2 –1 –2 G=5 –3 –4 –5 –6 Figure 5. Small Signal Frequency Response vs. Gain NORMALIZED CLOSED-LOOP GAIN (dB) G=1 –1 G=5 –2 G=2 –3 –4 –5 G=2 VOUT = 2V p-p 0 G=1 VOUT = 1.4V p-p –1 –2 –3 G=5 VOUT = 2V p-p –4 –5 VS = 3.3V VS = 3.3V 1 10 100 FREQUENCY (MHz) 1000 –6 07685-005 –6 1 Figure 6. Small Signal Frequency Response vs. Gain 1000 Figure 9. Large Signal Frequency Response vs. Gain 1 1 RL = 1kΩ CF = 4.4pF CF = 6.6pF 0 CLOSED-LOOP GAIN (dB) 0 100 10 FREQUENCY (MHz) –1 RL = 150Ω –2 –3 –4 –5 CF = 2.2pF –1 –2 –3 –4 –5 1 10 100 FREQUENCY (MHz) 1000 –6 07685-006 –6 1 Figure 7. Small Signal Frequency Response vs. Load 100 10 FREQUENCY (MHz) 1000 Figure 10. Small Signal Frequency Response vs. Capacitive Load Rev. 0 | Page 7 of 20 07685-009 NORMALIZED CLOSED-LOOP GAIN (dB) 1 0 1000 Figure 8. Large Signal Frequency Response vs. Gain 1 CLOSED-LOOP GAIN (dB) 100 10 FREQUENCY (MHz) 1 07685-008 –2 0 07685-007 NORMALIZED CLOSED-LOOP GAIN (dB) 1 07685-004 NORMALIZED CLOSED-LOOP GAIN (dB) 1 0.2 6.2 0.1 6.1 CLOSED-LOOP GAIN (dB) VS = 3.3V, VOUT = 1.4V p-p –0.1 VS = 5V, VOUT = 2V p-p –0.2 –0.3 1 10 100 FREQUENCY (MHz) 5.8 5.7 G=2 5.5 1000 1 10 100 FREQUENCY (MHz) Figure 11. 0.1 dB Flatness vs. Supply Voltage 1 0 75 –50 PHASE 50 GAIN (dB) –2 –3 –100 GAIN 25 –150 0 –200 –25 –250 –4 –6 07685-038 –5 1 10 100 FREQUENCY (MHz) 1000 –50 10 100k 1M 10M 100M 1G –300 10G –50 VOUT = 1V p-p VS = 3.3V RL = 1kΩ –60 –60 VOUT = 1V p-p RL = 1kΩ DISTORTION (dBc) –70 –65 –70 –75 HD2 –80 HD3 –85 1 FREQUENCY (MHz) –80 –90 –100 HD2 –110 –120 07685-014 DISTORTION (dBc) 10k Figure 15. Open-Loop Gain and Phase vs. Frequency –50 –90 0.1 1k FREQUENCY (Hz) Figure 12. Small Signal Frequency Response vs. Temperature –55 100 10 –130 0.1 40 Figure 13. Harmonic Distortion vs. Frequency HD3 07685-011 CLOSED-LOOP GAIN (dB) 100 TA = –40°C TA = +25°C –1 1000 Figure 14. 0.1 dB Flatness vs. Supply Voltage TA = +85°C TA = +105°C 0 07685-040 –0.5 VS = 3.3V 5.9 5.6 07685-037 –0.4 6.0 PHASE (Degrees) 0 VS = 5V 1 FREQUENCY (MHz) 10 Figure 16. Harmonic Distortion vs. Frequency Rev. 0 | Page 8 of 20 40 07685-035 CLOSED-LOOP GAIN (dB) ADA4855-3 ADA4855-3 0 –40 –50 –60 –40 OUT3 –60 IN2, IN3, OUT1 CROSSTALK (dB) OUT1 –80 –70 IN1, IN2, OUT3 –80 –90 IN1, IN3, OUT2 –100 OUT2 –120 –110 07685-012 –100 0.1 1 10 FREQUENCY (MHz) 100 –120 1000 07685-015 FORWARD ISOLATION (dB) –20 1 100 10 1000 FREQUENCY (MHz) Figure 17. Forward Isolation vs. Frequency Figure 20. Crosstalk vs. Frequency 0 –30 –10 –40 –20 –50 CMRR (dB) PSRR (dB) –30 –40 –PSRR +PSRR –50 –60 –70 –60 –70 –80 –80 0.1 1 10 FREQUENCY (MHz) –100 0.01 100 Figure 18. Power Supply Rejection Ratio (PSRR) vs. Frequency 0.1 1 10 FREQUENCY (MHz) 100 Figure 21. Common-Mode Rejection Ratio (CMRR) vs. Frequency 100 07685-020 10 1 10 100 1k 10k 100k FREQUENCY (Hz) 1M VS = 5V VS = 3.3V 10 1 10M 07685-017 VOLTAGE NOISE (nV/√Hz) 100 CURRENT NOISE (pA/√Hz) 07685-016 –100 0.01 –90 07685-013 –90 10 100 1k 10k FREQUENCY (Hz) 100k Figure 22. Input Voltage Noise vs. Frequency Figure 19. Input Current Noise vs. Frequency Rev. 0 | Page 9 of 20 1M ADA4855-3 0.08 CL = 2.2pF CL = 4.4pF CL = 6.6pF 1.0 0.04 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 0.06 1.5 VS = 3.3V VS = 5V 0.02 0 –0.02 0.5 0 –0.5 –0.04 07685-018 –1.5 TIME (10ns/DIV) TIME (10ns/DIV) Figure 26. Large Signal Transient Response vs. Capacitive Load 0.08 0.08 0.06 0.06 0.02 CL = 2.2pF CL = 4.4pF CL = 6.6pF OUTPUT VOLTAGE (V) 0.04 0 –0.02 0.02 0 –0.02 –0.04 –0.06 –0.06 –0.08 VS = 3.3V –0.08 TIME (10ns/DIV) TIME (10ns/DIV) Figure 27. Small Signal Transient Response vs. Capacitive Load Figure 24. Small Signal Transient Response vs. Capacitive Load 1.5 CL = 2.2pF CL = 4.4pF CL = 6.6pF 0.04 –0.04 07685-019 OUTPUT VOLTAGE (V) Figure 23. Small Signal Transient Response vs. Supply Voltage 07685-023 –0.08 07685-022 –1.0 –0.06 23.7 RL = 150Ω RL = 1kΩ QUIESCENT CURRENT (mA) 0.5 0 –0.5 23.2 22.7 22.2 –1.5 21.7 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5 TIME (10ns/DIV) SUPPLY VOLTAGE (V) Figure 28. Quiescent Current vs. Supply Voltage Figure 25. Large Signal Transient Response vs. Load Resistance Rev. 0 | Page 10 of 20 07685-029 –1.0 07685-021 OUTPUT VOLTAGE (V) 1.0 ADA4855-3 4 2.5 2 × VIN 3 2.0 2 × VIN 1.5 2 VOUT VOLTAGE (V) 1 VOLTAGE (V) VOUT 1.0 0 –1 0.5 0 –0.5 –1.0 –2 –1.5 –4 –2.0 –2.5 TIME (50ns/DIV) Figure 29. Output Overdrive Recovery Figure 32. Output Overdrive Recovery 3 2.0 VOUT = 1V p-p VS = 3.3V CL = 2.2pF CL = 4.4pF CL = 6.6pF VPD VOUT 1.5 0.2 0 –0.2 2 1.0 OUTPUT VOLTAGE (V) 0.4 OUTPUT VOLTAGE (V) TIME (50ns/DIV) 1 0.5 0 0 –0.5 –1 –1.0 –0.4 –2 07685-026 –1.5 –0.6 –2.0 TIME (10ns/DIV) 0.5 0.4 0.4 0.3 0.3 SETTLING TIME (%) INPUT 0.1 0 ERROR –0.1 –0.2 0.2 0.1 0 –0.1 ERROR –0.2 –0.4 –0.5 TIME (2ns/DIV) 07685-027 –0.4 –0.5 INPUT –0.3 –0.3 07685-024 SETTLING TIME (%) Figure 33. Turn-On/Turn-Off Time 0.5 0.2 –3 TIME (1µs/DIV) Figure 30. Large Signal Transient Response vs. Capacitive Load 07685-129 0.6 G=2 VIN = 3.3V POWER-DOWN VOLTAGE (V) G=2 07685-028 07685-025 –3 VS = 3.3V TIME (2ns/DIV) Figure 34. Settling Time Figure 31. Settling Time Rev. 0 | Page 11 of 20 ADA4855-3 0 100 OUTPUT IMPEDANCE (Ω) OFFSET VOLTAGE (mV) –10 –20 –30 VS = 3.3V –40 VS = 5V 10 1 0.1 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 COMMON-MODE VOLTAGE (V) 4.5 Figure 35. Input Offset Voltage vs. Common-Mode Voltage 4.95 23.2 SATURATION VOLTAGE (mV) QUIESCENT CURRENT (mA) 1000 5.00 23.0 22.8 22.6 VS = 3.3V 22.4 22.2 4.90 4.85 4.80 4.75 4.70 4.65 –25 –10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 07685-032 22.0 Figure 36. Quiescent Current vs. Temperature 2.2 2.0 1.8 1.6 1.4 07685-034 1.2 –20 0 20 40 60 TEMPERATURE (°C) 80 4.60 0.01 0.1 1 LOAD CURRENT (mA) 10 Figure 39. Output Saturation Voltage vs. Load Current 2.4 OFFSET VOLTAGE (mV) 10 100 FREQUENCY (MHz) VS = 5V 23.4 1.0 –40 1 Figure 38. Output Impedance vs. Frequency 23.6 21.8 –40 07685-036 0.01 0.1 5.0 07685-039 –60 07685-031 –50 100 Figure 37. Offset Drift vs. Temperature Rev. 0 | Page 12 of 20 100 ADA4855-3 TEST CIRCUITS +VS 10µF +VS + 10µF + 1kΩ 0.1µF 0.1µF VIN VOUT VIN RL 49.9Ω 0.1µF 1kΩ 0.1µF VOUT 1kΩ RL 1kΩ 53.6Ω 10µF + 0.1µF 07685-041 0.1µF –VS 07685-044 + 10µF –VS Figure 40. Noninverting Load Configuration Figure 43. Common-Mode Rejection +VS +VS 10µF AC + 49.9Ω 0.1µF VOUT VOUT RL RL 49.9Ω AC 07685-042 0.1µF –VS –VS Figure 41. Positive Power Supply Rejection Figure 44. Negative Power Supply Rejection +VS +VS 10µF 10µF + + RF RG 0.1µF 0.1µF VOUT VIN CL 49.9Ω RF 0.1µF VOUT VIN RL RL 49.9Ω 10µF 0.1µF –VS + 07685-043 + 10µF 0.1µF 0.1µF –VS Figure 42. Typical Capacitive Load Configuration 07685-046 RG 07685-045 + 10µF Figure 45. Typical Noninverting Gain Configuration Rev. 0 | Page 13 of 20 ADA4855-3 THEORY OF OPERATION Besides a novel input stage, the ADA4855 employs the Analog Devices, Inc., patented rail-to-rail output stage. This output stage makes efficient use of the power supplies, allowing the op amp to drive up to three video loads to within 350 mV of the positive power rail. In addition, this output stage provides the amplifier with very fast overdrive characteristics, which is an important property in video applications. The ADA4855 comes in a 16-lead LFCSP that has an exposed thermal pad for lower operating temperature. This pad is internally connected to the negative rail. To avoid printed circuit board (PCB) layout problems, the ADA4855 features a new pinout flow that is optimized for video applications. As shown in Figure 4, the noninverting input and output pins of each amplifier are adjacent to each other for ease of layout. The ADA4855 is fabricated in Analog Devices dielectrically isolated eXtra Fast Complementary Bipolar 3 (XFCB3) process, which results in the outstanding speed and dynamic range displayed by the amplifier. +VS C1 Gm2 +IN –IN R C –VS Figure 46. High Level Design Schematic Rev. 0 | Page 14 of 20 OUT Gm1 07685-147 The ADA4855 is a voltage feedback op amp that employs a new input stage that achieves a high slew rate while maintaining a wide common-mode input range. The input common-mode range of the ADA4855 extends from 200 mV below the negative rail to 1 V below the positive rail. This feature makes the ADA4855 ideal for single-supply applications. In addition, this new input stage does not sacrifice noise performance for slew rate. At 6.8 nV/√Hz, the ADA4855 is one of the lowest noise rail-torail output video amplifiers in the market. ADA4855-3 APPLICATIONS INFORMATION GAIN CONFIGURATIONS 20 MHz ACTIVE LOW-PASS FILTER The ADA4855-3 is a single-supply, high speed, voltage feedback amplifier. Table 6 provides a convenient reference for quickly determining the feedback and gain set resistor values and bandwidth for common gain configurations. The ADA4855-3 triple amplifier lends itself to higher order active filters. Figure 49 shows a 20 MHz, 6-pole, Sallen-Key low-pass filter. R7 1kΩ R8 261Ω Table 6. Recommended Values and Frequency Performance1 RG N/A 1 kΩ 200 Ω – VIN R1 232Ω C1 15pF Conditions: VS = 5 V, TA = 25°C, RL = 150 Ω. Figure 47 and Figure 48 show the typical noninverting and inverting configurations and recommended bypass capacitor values. +VS C2 6.6pF R9 R10 1kΩ 261Ω – R3 309Ω 10µF 0.1µF VIN OUT2 U2 OP AMP + R4 1.87kΩ C3 15pF C4 4.3pF + ADA4855-3 VOUT 0.1µF – RF R12 261Ω – R5 261Ω 07685-047 OUT3 VOUT C6 3pF Figure 49. 20 MHz, 6-Pole Low-Pass Filter Figure 47. Noninverting Gain Configuration The filter has a gain of approximately 6 dB and flat frequency response out to 14 MHz. This type of filter is commonly used at the output of a video DAC as a reconstruction filter. The frequency response of the filter is shown in Figure 50. RF +VS U3 OP AMP + R6 1.43kΩ C5 33pF –VS RG 10µF 10 0.1µF RG R11 1kΩ 0.1µF 10µF OUT3 0 OUT2 – OUT1 –10 ADA4855-3 MAGNITUDE (dB) VOUT 0.1µF + 0.1µF 10µF –VS –20 –30 –40 –50 07685-048 VIN OUT1 U1 OP AMP + R2 1.69kΩ 07685-049 1 RF 0Ω 1 kΩ 1 kΩ Large Signal 0.1 dB Flatness (MHz) 53 50 6 –60 –70 Figure 48. Inverting Gain Configuration 1 10 FREQUENCY (MHz) 100 Figure 50. 20 MHz, Low-Pass Filter Frequency Response Rev. 0 | Page 15 of 20 200 07685-050 Gain 1 2 5 −3 dB SS BW (MHz) 200 120 45 ADA4855-3 6.5 RGB VIDEO DRIVER 6.0 Figure 51 shows a typical RGB driver application using dual supplies. The gain of the amplifier is set at +2, where RF = RG = 1 kΩ. The amplifier inputs are terminated with shunt 75 Ω resistors, and the outputs have series 75 Ω resistors for proper video matching. In Figure 51, the PD pin is not shown connected to any signal source for simplicity. If the power-down function is not used, it is recommended that the PD pin be tied to the positive supply or be left floating (not connected). RL = 150Ω RL = 75Ω RL = 50Ω MAGNITUDE (dB) 5.5 5.0 4.5 4.0 VOUT = 2V p-p G=2 3.5 75Ω 1kΩ 1kΩ VIN (R) 75Ω 2.5 VOUT (R) 07685-153 3.0 1 10 FREQUENCY (MHz) –VS 16 15 14 PD (POWER-DOWN) PIN 13 0.1µF VIN (G) 75Ω 1 12 2 11 ADA4855-3 3 10 PD 4 9 5 6 7 +VS 75Ω VOUT (G) 1kΩ 1kΩ +VS 0.1µF 8 + 10µF 0.1µF 0.1µF VIN (B) –VS 75Ω 75Ω 1kΩ VOUT (B) 07685-051 1kΩ Figure 51. RGB Video Driver DRIVING MULTIPLE VIDEO LOADS Each amplifier in the ADA4855-3 can drive up to three video loads simultaneously, as shown in Figure 52. When driving three video loads, the ADA4855-3 maintains its excellent performance for 0.1 dB flatness and 3 dB bandwidth. Figure 53 shows the large signal frequency response of the ADA4855-3 with three different load configurations: 150 Ω, 75 Ω and 50 Ω. The ADA4855-3 is equipped with a PD (power-down) pin for all three amplifiers. This allows the user to reduce the quiescent supply current when an amplifier is inactive. The power-down threshold levels are derived from the voltage applied to the +VS pin. When used in single-supply applications, this is especially useful with conventional logic levels. The amplifier is enabled when the voltage applied to the PD pin is greater than +VS − 1.25 V. In a single-supply application, the voltage threshold is typically +3.75 V, and in a ±2.5 V dualsupply application, the voltage threshold is typically +1.25 V. The amplifier is also enabled when the PD pin is left floating (not connected). However, the amplifier is powered down when the voltage on the PD pin is lower than 2.5 V from +VS. If the PD pin is not used, it is best to connect it to the positive supply. Table 7. Power-Down Voltage Control PD Pin 5V ±2.5 V 3V Not Active Active >3.75 V <2 V >1.25 V <0 V >1.75 V <1 V RF 1kΩ 10µF 75Ω 75Ω CABLE RG 1kΩ 75Ω 75Ω CABLE – ADA4855-3 0.1µF + 75Ω CABLE 0.1µF VIN 75Ω –VS VOUT1 75Ω 0.1µF 10µF VOUT2 75Ω 75Ω 75Ω CABLE VOUT3 75Ω 07685-052 +VS 200 Figure 53. Large Signal Frequency Response vs. Loads 10µF + 0.1µF 0.1µF 100 Figure 52. Video Driver Schematic for Triple Video Loads Rev. 0 | Page 16 of 20 ADA4855-3 SINGLE-SUPPLY OPERATION POWER SUPPLY BYPASSING The ADA4855-3 is designed for a single power supply. Figure 54 shows the schematic for a single 5 V supply video driver. The input signal is ac-coupled into the amplifier via C1. Resistor R2 and Resistor R4 establish the input midsupply reference for the amplifier. C5 prevents constant current from being drawn through the gain set resistor. C6 is the output coupling capacitor. For more information on ac-coupled single-supply operation of op amps, see Avoiding Op-Amp Instability Problems in SingleSupply Applications, Analog Dialogue, Volume 35, Number 2, March-May, 2001, at www.analog.com. Careful attention must be paid to bypassing the power supply pins of the ADA4855-3. 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, 2.2 μF to 47 μF capacitor located in close proximity to the ADA4855-3 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 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. 5V 5V R2 50kΩ C2 1µF C3 10µF R4 50kΩ C4 0.01µF R3 1kΩ R1 75Ω LAYOUT C6 220µF VIN C1 22µF U1 R7 75Ω VOUT R8 75Ω R6 1kΩ R5 1kΩ –VS ADA4855-3 07685-155 C5 22µF Figure 54. AC-Coupled, Single-Supply Video Driver Schematic Another way to configure the ADA4855-3 in single-supply operation is dc-coupled. The common-mode input voltage can go ~200 mV below ground, which makes it a true single-supply amplifier. However, in video applications, the black level is set at 0 V, which means that the output of the amplifier must go to ground level as well. The ADA4855-3 has a rail-to-rail output that can swing to within 100 mV from either rail. Figure 55 shows the schematic for adding 50 mV dc offset to the input signal so that the output is not clipped while still properly terminating the input with 75 Ω. C1 10µF 5V 5V C2 0.1µF 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 ADA4855-3 can operate at up to 410 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, September 2005, at www.analog.com. R1 3.74kΩ VIN R2 76.8Ω U1 VOUT R6 75Ω R4 1kΩ –VS ADA4855-3 07685-156 R3 1kΩ R5 75Ω Figure 55. DC-Coupled, Single-Supply Video Driver Schematic Rev. 0 | Page 17 of 20 ADA4855-3 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 (BOTTOM VIEW) 9 0.80 MAX 0.65 TYP SEATING PLANE 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 16 13 12 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. 072808-A PIN 1 INDICATOR 0.60 MAX 0.60 MAX COMPLIANT TO JEDEC STANDARDS MO-220-VGGC Figure 56.16-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 ADA4855-3YCPZ-R2 1 ADA4855-3YCPZ-R71 ADA4855-3YCPZ-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. Rev. 0 | Page 18 of 20 Package Option CP-16-4 CP-16-4 CP-16-4 Ordering Quantity 250 1,500 5,000 ADA4855-3 NOTES Rev. 0 | Page 19 of 20 ADA4855-3 NOTES ©2008 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D07685-0-11/08(0) Rev. 0 | Page 20 of 20