Order Now Product Folder Support & Community Tools & Software Technical Documents OPA1678, OPA1679 SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 OPA167x Low-Distortion Audio Operational Amplifiers 1 Features 3 Description • • • • • The OPA1678 (dual-channel) and OPA1679 (quadchannel) operational amplifiers offer higher systemlevel performance over legacy op amps commonly used in audio circuitry. The OPA167x amplifiers achieve a low 4.5-nV/√Hz noise density and low distortion of 0.0001% at 1 kHz which improves audio signal fidelity. They also offer rail-to-rail output swing to within 800 mV with a 2-kΩ load, which increases headroom and maximizes dynamic range. 1 • • • • • • • • Low Noise: 4.5 nV/√Hz at 1 kHz Low Distortion: 0.0001% at 1 kHz High Open-Loop Gain: 114dB High Common-Mode Rejection: 110 dB Low Quiescent Current: – 2 mA Per Channel Low Input Bias Current: 10 pA (Typical) Slew Rate: 9 V/μs Wide Gain Bandwidth: 16 MHz (G = 1) Unity-Gain Stable Rail-to-Rail Output Wide Supply Range: – ±2.25 V to ±18 V, or 4.5 V to 36 V Dual-Channel and Quad-Channel Versions Small Package Sizes: – Dual-Channel: SO-8, MSOP-8, SON-8 – Quad-Channel: SO-14, TSSOP-14, QFN-16 The OPA167x amplifiers use completely independent internal circuitry for lowest crosstalk and freedom from interactions between channels, even when overdriven or overloaded. The OPA167x temperature ranges are specified from –40°C to +85°C. 2 Applications • • • • • The OPA1678 and OPA1679 operate over a very wide supply range of ±2.25 V to ±18 V or (4.5 V to 36 V) on only 2 mA of supply current to accommodate the power supply constraints of many types of audio products. These op amps are unity-gain stable and provide excellent dynamic behavior over a wide range of load conditions allowing them to be used in many audio circuits. Analog Signal Conditioning Analog and Digital Mixers Audio Effects Pedals A/V Receivers Car Audio Systems Device Information(1) PART NUMBER OPA1678 OPA1679 PACKAGE BODY SIZE (NOM) SOIC (8) 4.90 mm × 3.91 mm VSSOP (8) 3.00 mm × 3.00 mm SON (8) 3.00 mm × 3.00 mm SOIC (14) 8.65 mm × 3.91 mm TSSOP (14) 5.00 mm × 4.40 mm (1) For all available packages, see the orderable addendum at the end of the data sheet. Simplified Internal Schematic V BIAS1 V + IN V Class AB Control Circuitry IN V V BIAS2 V O Total Harmonic Distortion +Noise (%) Tail Current 0.1 -60 Gain = 10 V/V Gain = 1 V/V Gain = -1 V/V 0.01 -80 0.001 -100 0.0001 -120 Total Harmonic Distortion + Noise (dB) THD+N vs Frequency (2-kΩ Load) V+ -140 0.00001 10 100 1k Frequency (Hz) 10k C002 1 An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectual property matters and other important disclaimers. PRODUCTION DATA. OPA1678, OPA1679 SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 www.ti.com Table of Contents 1 2 3 4 5 6 7 Features .................................................................. Applications ........................................................... Description ............................................................. Revision History..................................................... Pin Configuration and Functions ......................... Specifications......................................................... 1 1 1 2 3 5 6.1 6.2 6.3 6.4 6.5 6.6 6.7 5 5 5 6 6 7 9 Absolute Maximum Ratings ...................................... ESD Ratings.............................................................. Recommended Operating Conditions....................... Thermal Information: OPA1678 ................................ Thermal Information: OPA1679 ................................ Electrical Characteristics: VS = ±15 V....................... Typical Characteristics .............................................. Detailed Description ............................................ 14 7.1 7.2 7.3 7.4 Overview ................................................................. Functional Block Diagram ....................................... Feature Description................................................. Device Functional Modes........................................ 14 14 14 18 8 Application and Implementation ........................ 19 8.1 Application Information............................................ 19 8.2 Typical Application .................................................. 20 9 Power Supply Recommendations...................... 26 10 Layout................................................................... 26 10.1 Layout Guidelines ................................................. 26 10.2 Layout Example .................................................... 27 10.3 Power Dissipation ................................................. 27 11 Device and Documentation Support ................. 28 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 Device Support...................................................... Documentation Support ........................................ Related Links ........................................................ Receiving Notification of Documentation Updates Community Resource............................................ Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 28 29 29 29 29 29 29 29 12 Mechanical, Packaging, and Orderable Information ........................................................... 30 4 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Original (February 2017) to Revision A Page • Added SON-8 package to Features list.................................................................................................................................. 1 • Added DRG (SON) 8-pin package to Device Information table ............................................................................................ 1 • Added DRG (SON) 8-pin pinout drawing to Pin Configuration and Functions section .......................................................... 3 • Added thermal pad information to Pin Functions: OPA1678 table......................................................................................... 3 • Added DRG (SON) thermal information to Thermal Information: OPA1678 table ................................................................. 6 2 Submit Documentation Feedback Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 OPA1678, OPA1679 www.ti.com SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 5 Pin Configuration and Functions OPA1678 D and DGK Packages 8-Pin SOIC and VSSOP Top View OPA1678 DRG Package 8-Pin SON With Exposed Thermal Pad Top View OUT A 1 8 V+ ±IN A 2 7 OUT B +IN A 3 6 ±IN B V± 4 5 +IN B OUT A 1 ±IN A 2 +IN A 3 V± 4 Thermal Pad 8 V+ 7 OUT B 6 ±IN B 5 +IN B Not to scale Not to scale Pin Functions: OPA1678 PIN I/O DESCRIPTION NAME NO. –IN A 2 I Inverting input, channel A +IN A 3 I Noninverting input, channel A –IN B 6 I Inverting input, channel B +IN B 5 I Noninverting input, channel B OUT A 1 O Output, channel A OUT B 7 O Output, channel B V– 4 — Negative (lowest) power supply V+ 8 — Positive (highest) power supply Thermal pad Exposed thermal die pad on underside; connect thermal die pad to V–. Soldering the thermal pad improves heat dissipation and provides specified performance. Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 Submit Documentation Feedback 3 OPA1678, OPA1679 SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 www.ti.com OPA1679 D and PW Packages 14-Pin SOIC and TSSOP Top View OUT A 1 14 OUT D ±IN A 2 13 ±IN D +IN A 3 12 +IN D V+ 4 11 V± +IN B 5 10 +IN C ±IN B 6 9 ±IN C OUT B 7 8 OUT C Not to scale Pin Functions: OPA1679 PIN I/O DESCRIPTION NAME NO. –IN A 2 I Inverting input, channel A +IN A 3 I Noninverting input, channel A –IN B 6 I Inverting input, channel B +IN B 5 I Noninverting input, channel B –IN C 9 I Inverting input, channel C +IN D 10 I Noninverting input, channel C –IN D 13 I Inverting input, channel D +IN D 12 I Noninverting input, channel D OUT A 1 O Output, channel A OUT B 7 O Output, channel B OUT C 8 O Output, channel C OUT D 14 O Output, channel D V+ 4 — Positive (highest) power supply V– 11 — Negative (lowest) power supply 4 Submit Documentation Feedback Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 OPA1678, OPA1679 www.ti.com SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 6 Specifications 6.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) (1) MIN Voltage Input V (V+) + 0.5 V –10 10 mA 125 °C 200 °C 150 °C Output short-circuit (2) Continuous Operating, TA Temperature –55 Junction, TJ Storage, Tstg (2) UNIT 40 (V–) – 0.5 Input (all pins except power-supply pins) Current (1) MAX Supply voltage, VS = (V+) – (V–) –65 Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. Short-circuit to VS / 2 (ground in symmetrical dual-supply setups), one amplifier per package. 6.2 ESD Ratings VALUE Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 V(ESD) (1) (2) Electrostatic discharge (1) UNIT ±2000 Charged-device model (CDM), per JEDEC specification JESD22-C101 (2) ±1000 Machine model (MM) ±200 V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. 6.3 Recommended Operating Conditions over operating free-air temperature range (unless otherwise noted) MIN Supply voltage TA NOM MAX UNIT 4.5 (±2.25) 36 (±18) V –40 85 °C Operating temperature Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 Submit Documentation Feedback 5 OPA1678, OPA1679 SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 www.ti.com 6.4 Thermal Information: OPA1678 OPA1678 THERMAL METRIC (1) D (SOIC) DGK (VSSOP) DRG (SON) 8 PINS 8 PINS 8 PINS UNIT 219 66.9 °C/W RθJA Junction-to-ambient thermal resistance 144 RθJC(top) Junction-to-case (top) thermal resistance 77 79 54.5 °C/W RθJB Junction-to-board thermal resistance 62 104 40.4 °C/W ψJT Junction-to-top characterization parameter 28 15 1.9 °C/W ψJB Junction-to-board characterization parameter 61 102 40.4 °C/W RθJC(bot) Junction-to-case (bottom) thermal resistance N/A N/A 10.8 °C/W (1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report. 6.5 Thermal Information: OPA1679 OPA1679 THERMAL METRIC (1) D (SOIC) PW (TSSOP) 14 PINS 14 PINS UNIT RθJA Junction-to-ambient thermal resistance 90 127 °C/W RθJC(top) Junction-to-case (top) thermal resistance 55 47 °C/W RθJB Junction-to-board thermal resistance 44 59 °C/W ψJT Junction-to-top characterization parameter 20 5.5 °C/W ψJB Junction-to-board characterization parameter 44 58 °C/W RθJC(bot) Junction-to-case (bottom) thermal resistance N/A N/A °C/W (1) 6 For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report. Submit Documentation Feedback Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 OPA1678, OPA1679 www.ti.com SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 6.6 Electrical Characteristics: VS = ±15 V at TA = 25°C, RL = 2 kΩ, and VCM = VOUT = midsupply, unless otherwise noted PARAMETER TEST CONDITIONS MIN TYP MAX UNIT AUDIO PERFORMANCE 0.0001% THD+N IMD Total harmonic distortion + noise Intermodulation distortion G=1 RL = 600 Ω f = 1 kHz VO = 3 VRMS G=1 VO = 3 VRMS –120 SMPTE/DIN Two-Tone, 4:1 (60 Hz and 7 kHz) 0.0001% DIM 30 (3-kHz square wave and 15-kHz sine wave) 0.0001% CCIF Twin-Tone (19 kHz and 20 kHz) 0.0001% dB –120 dB –120 dB –120 dB FREQUENCY RESPONSE GBW Gain-bandwidth product G=1 16 SR Slew rate G = –1 9 MHz V/µs Full power bandwidth (1) VO = 1 VP 1.4 MHz Overload recovery time G = –10 Channel separation (dual and quad) f = 1 kHz 1 µs –130 dB NOISE en Input voltage noise In f = 20 Hz to 20 kHz 5.4 f = 0.1 Hz to 10 Hz 1.74 µVPP Input voltage noise density f = 1 kHz 4.5 nV/√Hz Input current noise density f = 1 kHz 3 fA/√Hz OFFSET VOLTAGE VS = ±2.25 V to ±18 V ±0.5 VOS Input offset voltage VS = ±2.25 V to ±18 V TA = –40°C to +85°C (2) 2 PSRR Power-supply rejection ratio VS = ±2.25 V to ±18 V 3 ±2 mV µV/°C 8 µV/V INPUT BIAS CURRENT IB Input bias current VCM = 0 V ±10 pA IOS Input offset current VCM = 0 V ±10 pA INPUT VOLTAGE RANGE VCM Common-mode voltage range (V–) + 0.5 CMRR Common-mode rejection ratio 100 (V+) – 2 V 110 dB INPUT IMPEDANCE Differential Common-mode 100 || 6 MΩ || pF 6000 || 2 GΩ || pF OPEN-LOOP GAIN Open-loop voltage gain (V–) + 0.8 V ≤ VO ≤ (V+) – 0.8 V RL = 2 kΩ VOUT Voltage output RL = 2 kΩ IOUT Output current ZO Open-loop output impedance ISC Short-circuit current (3) CLOAD Capacitive load drive AOL 106 114 dB OUTPUT (1) (2) (3) (V–) + 0.8 (V+) – 0.8 See Typical Characteristics curves f = 1 MHz See Typical Characteristics curves V mA Ω 50/–50 mA 100 pF Full-power bandwidth = SR / (2π × VP), where SR = slew rate. Specified by design and characterization One channel at a time Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 Submit Documentation Feedback 7 OPA1678, OPA1679 SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 www.ti.com Electrical Characteristics: VS = ±15 V (continued) at TA = 25°C, RL = 2 kΩ, and VCM = VOUT = midsupply, unless otherwise noted PARAMETER TEST CONDITIONS MIN TYP MAX UNIT POWER SUPPLY VS IQ Specified voltage Quiescent current (per channel) ±2.25 IOUT = 0 A 2 IOUT = 0 A TA = –40°C to +85°C (2) ±18 V 2.5 mA 2.8 mA TEMPERATURE 8 Specified range –40 85 °C Operating range –55 125 °C Submit Documentation Feedback Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 OPA1678, OPA1679 www.ti.com SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 6.7 Typical Characteristics at TA = 25°C, VS = ±15 V, and RL = 2 kΩ, (unless otherwise noted) Voltage (200nV/div) 9ROWDJH 1RLVH 6SHFWUDO 'HQVLW\ Q9 ¥+] 1000 100 10 1 1 10 100 1k 10k Time (1s/div) 100k Frequency (Hz) C003 C001 Figure 1. Input Voltage Noise Density vs Frequency 2XWSXW 9ROWDJH 1RLVH Q9 ¥+] 10000 Figure 2. 0.1-Hz to 10-Hz Noise 20 Resistor Noise Contribution Voltage Noise Contribution Current Noise Contribution Total Noise 16 Output Voltage (V) 1000 100 10 14 12 10 8 6 4 1 2 0.1 0 10 100 1k 10k 100k 1M 10M 100M 1000M Source Resistance (O) 10k Gain Phase 120 20 40 10 Gain (dB) Phase (s) 90 0 ±10 ±20 45 20 ±30 0 ±20 100 1k 10k 100k 1M 10M Frequency (Hz) C015 Figure 4. Maximum Output Voltage vs Frequency 80 60 10M 30 180 135 100 1M Frequency (Hz) Figure 3. Voltage Noise vs Source Resistance 10 100k C001 140 Gain (dB) VS = +/- 18 V VS = +/- 5 V VS = +/- 2.25 V 18 0 100M ±40 100k Gain = -1 V/V Gain = 1 V/V Gain = 10 V/V 1M 10M Frequency (Hz) C006 CL = 10 pF 100M C002 CL = 10 pF Figure 5. Open-Loop Gain and Phase vs Frequency Figure 6. Closed-Loop Gain vs Frequency Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 Submit Documentation Feedback 9 OPA1678, OPA1679 SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 www.ti.com Typical Characteristics (continued) 0.01 -80 0.001 -100 0.0001 -120 -140 10 100 1k 0.01 -80 0.001 -100 0.0001 -120 -140 0.00001 10k 10 Frequency (Hz) VOUT = 3 VRMS 100 Bandwidth = 80 kHz 0.001 -100 -120 0.01 -140 0.1 1 RL = 2 kΩ -60 0.01 -80 0.001 -100 Gain = 1 V/V Gain = -1 V/V Gain = 10 V/V 0.01 -140 0.1 1 10 Output Amplitude (VRMS) C002 Bandwidth = 80 kHz f = 1 kHz Figure 9. THD+N Ratio vs Output Amplitude RL = 600 Ω C002 Bandwidth = 80 kHz Figure 10. THD+N Ratio vs Output Amplitude 140 ±70 120 ±80 CMRR, PSRR (dB) Channel Separation (dB) -120 0.0001 ±60 ±90 ±100 ±110 ±120 ±130 ±140 100 80 60 40 CMRR PSRR(+) PSRR(-) 20 ±150 0 ±160 10 100 1k 10k 100k 1M 10M Frequency (Hz) VOUT = 3 VRMS 10 100 1k 10k 100k 1M Frequency (Hz) C006 10M C006 Gain = 1 V/V Figure 11. Channel Separation vs Frequency 10 Bandwidth = 80 kHz 0.1 0.00001 0.001 10 Output Amplitude (VRMS) f = 1 kHz Total Harmonic Distortion +Noise (%) -80 Total Harmonic Distortion + Noise (dB) Total Harmonic Distortion +Noise (%) 0.01 Gain = 1 V/V Gain = -1 V/V Gain = 10 V/V C002 RL = 600 Ω Figure 8. THD+N Ratio vs Frequency -60 0.0001 10k Frequency (Hz) VOUT = 3 VRMS Figure 7. THD+N Ratio vs Frequency 0.1 0.00001 0.001 1k C002 RL = 2 kΩ -60 Gain = 10 V/V Gain = 1 V/V Gain = -1 V/V Total Harmonic Distortion + Noise (dB) 0.00001 0.1 Total Harmonic Distortion + Noise (dB) -60 Gain = 10 V/V Gain = 1 V/V Gain = -1 V/V Total Harmonic Distortion +Noise (%) Total Harmonic Distortion +Noise (%) 0.1 Total Harmonic Distortion + Noise (dB) at TA = 25°C, VS = ±15 V, and RL = 2 kΩ, (unless otherwise noted) Submit Documentation Feedback Figure 12. CMRR and PSRR vs Frequency (Referred to Input) Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 OPA1678, OPA1679 www.ti.com SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 Typical Characteristics (continued) at TA = 25°C, VS = ±15 V, and RL = 2 kΩ, (unless otherwise noted) Voltage (25 mV/div) VIN VOUT Voltage (25 mV/div) VIN VOUT Time (0.2 s/div) Time (0.2 s/div) C009 Gain = 1 V/V CL = 100 pF C009 Gain = –1 V/V CL = 100 pF VIN VOUT VIN VOUT Voltage (2.5 V/div) Figure 14. Small-Signal Step Response (100 mV) Voltage (2.5 V/div) Figure 13. Small-Signal Step Response (100 mV) Time (1 s/div) Time (1 s/div) C009 Gain = +1 V/V RF = 2 kΩ CL = 100 pF C009 Gain = –1 V/V Figure 15. Large-Signal Step Response CL = 100 pF Figure 16. Large-Signal Step Response 1000 145 140 Input Bias Current (pA) Open-Loop Gain (dB) 500 135 130 125 120 115 110 0 -500 -1000 IB(N) -1500 IB(P) 105 100 I(OS) -2000 ±40 ±15 10 35 60 85 Temperature (ƒC) 110 ±40 ±15 Figure 17. Open-Loop Gain vs Temperature 10 35 60 85 Temperature (ƒC) C008 110 C008 Figure 18. IB and IOS vs Temperature Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 Submit Documentation Feedback 11 OPA1678, OPA1679 SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 www.ti.com Typical Characteristics (continued) at TA = 25°C, VS = ±15 V, and RL = 2 kΩ, (unless otherwise noted) 8 3 6 2.8 2.6 Supply Current (mA) Input Bias Current (pA) 4 2 0 -2 -4 -8 ±18 ±15 ±12 ±9 ±6 ±3 0 3 6 9 12 15 Common-Mode Voltage (V) 2.2 2 1.8 1.6 1.4 IB(N) IB(P) I(OS) -6 2.4 1.2 1 18 ±40 10 ±15 35 60 85 110 Temperature (ƒC) C008 Figure 19. IB and IOS vs Common-Mode Voltage C008 Figure 20. Supply Current vs Temperature 20 3 18 Output Voltage Swing (V) Supply Current (mA) 2.5 2 1.5 1 0.5 0 5 10 15 20 25 30 35 Supply Voltage (V) 12 10 8 6 -40°C 4 0°C 2 25°C 85°C 0 40 0 85°C 20 25 30 35 40 45 50 55 60 C004 80 ISC (+) Short-Circuit Current (mA) 25°C -6 15 Figure 22. Output Voltage vs Output Current (Sourcing) 0°C -4 10 C008 -40°C -2 5 Output Current (mA) Figure 21. Supply Current vs Supply Voltage Output Voltage Swing (V) 14 0 0 -8 -10 -12 -14 -16 60 ISC (-) 40 20 0 ±20 ±40 -18 -20 ±60 0 5 10 15 20 25 30 Output Current (mA) 35 40 45 50 Submit Documentation Feedback ±40 ±15 10 35 60 85 110 135 Temperature (sC) C004 Figure 23. Output Voltage vs Output Current (Sinking) 12 16 C003 Figure 24. Short-Circuit Current vs Temperature Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 OPA1678, OPA1679 www.ti.com SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 Typical Characteristics (continued) at TA = 25°C, VS = ±15 V, and RL = 2 kΩ, (unless otherwise noted) 70 60 50 50 Overshoot (%) Phase Margin (s) 60 40 30 20 40 30 20 10 10 0 VS = +/- 18 V VS = +/- 2.25 V 0 0 100 200 300 400 500 600 Capacitive Load (pF) 0 100 300 400 500 600 Capacitive Load (pF) C002 G=1 C001 G=1 Figure 25. Phase Margin vs Capacitive Load Figure 26. Percent Overshoot vs Capacitive Load 10 20 5 15 0 10 Voltage (V) Voltage (V) 200 -5 -10 5 0 -15 -5 VIN VOUT -20 VIN VOUT -10 Time (500 ns/div) Time (500 ns/div) C004 C004 Gain = –10 V/V Gain = –10 V/V Figure 27. Negative Overload Recovery Figure 28. Positive Overload Recovery 10000 20 15 10 Voltage (V) Impedance (O) 1000 100 10 5 0 -5 -10 -15 1 -20 10 100 1k 10k 100k 1M Frequency (Hz) 10M 100M VIN VOUT Time (125 s/div) C015 C004 Gain = 1 V/V Figure 29. Open-Loop Output Impedance vs Frequency Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 Figure 30. No Phase Reversal Submit Documentation Feedback 13 OPA1678, OPA1679 SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 www.ti.com 7 Detailed Description 7.1 Overview The OPA167x devices are unity-gain stable, dual– and quad-channel op amps with low noise and distortion. The Functional Block Diagram shows a simplified schematic of the OPA167x (one channel shown). The device consists of a low noise input stage with a folded cascode and a rail-to-rail output stage. This topology exhibits superior noise and distortion performance across a wide range of supply voltages that are not delivered by legacy commodity audio operational amplifiers. 7.2 Functional Block Diagram V+ Tail Current V BIAS1 V + IN V Class AB Control Circuitry V O IN V BIAS2 V 7.3 Feature Description 7.3.1 Phase Reversal Protection The OPA167x family has internal phase-reversal protection. Many op amps exhibit phase reversal when the input is driven beyond the linear common-mode range. This condition is most often encountered in noninverting circuits when the input is driven beyond the specified common-mode voltage range, causing the output to reverse into the opposite rail. The input of the OPA167x prevents phase reversal with excessive common-mode voltage. Instead, the appropriate rail limits the output voltage. This performance is shown in Figure 31. 20 15 Voltage (V) 10 5 0 -5 -10 -15 -20 VIN VOUT Time (125 s/div) C004 Figure 31. Output Waveform Devoid of Phase Reversal During an Input Overdrive Condition 14 Submit Documentation Feedback Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 OPA1678, OPA1679 www.ti.com SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 Feature Description (continued) 7.3.2 Electrical Overstress Designers often ask questions about the capability of an operational amplifier to withstand electrical overstress. These questions tend to focus on the device inputs, but can involve the supply voltage pins or even the output pin. Each of these different pin functions have electrical stress limits determined by the voltage breakdown characteristics of the particular semiconductor fabrication process and specific circuits connected to the pin. Additionally, internal electrostatic discharge (ESD) protection is built into these circuits to protect them from accidental ESD events both before and during product assembly. A good understanding of this basic ESD circuitry and the relevance to an electrical overstress event is helpful. Figure 32 illustrates the ESD circuits contained in the OPA167x (indicated by the dashed line area). The ESD protection circuitry involves several current-steering diodes connected from the input and output pins and routed back to the internal power-supply lines, where the diodes meet at an absorption device internal to the operational amplifier. This protection circuitry is intended to remain inactive during normal circuit operation. TVS + ± RF +VS R1 IN± 250 Ÿ RS IN+ 250 Ÿ + Power-Supply ESD Cell ID VIN RL + ± + ± ±VS TVS Figure 32. Equivalent Internal ESD Circuitry Relative to a Typical Circuit Application An ESD event produces a short-duration, high-voltage pulse that is transformed into a short-duration, highcurrent pulse when discharging through a semiconductor device. The ESD protection circuits are designed to provide a current path around the operational amplifier core to prevent damage. The energy absorbed by the protection circuitry is then dissipated as heat. When an ESD voltage develops across two or more amplifier device pins, current flows through one or more steering diodes. Depending on the path that the current takes, the absorption device can activate. The absorption device has a trigger, or threshold voltage, that is above the normal operating voltage of the OPA167x but below the device breakdown voltage level. When this threshold is exceeded, the absorption device quickly activates and clamps the voltage across the supply rails to a safe level. When the operational amplifier connects into a circuit (see Figure 32), the ESD protection components are intended to remain inactive and do not become involved in the application circuit operation. However, circumstances may arise where an applied voltage exceeds the operating voltage range of a given pin. If this condition occurs, there is a risk that some internal ESD protection circuits can turn on and conduct current. Any such current flow occurs through steering-diode paths and rarely involves the absorption device. Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 Submit Documentation Feedback 15 OPA1678, OPA1679 SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 www.ti.com Feature Description (continued) Figure 32 shows a specific example where the input voltage (VIN) exceeds the positive supply voltage (V+) by 500 mV or more. Much of what happens in the circuit depends on the supply characteristics. If V+ can sink the current, one of the upper input steering diodes conducts and directs current to V+. Excessively high current levels can flow with increasingly higher VIN. As a result, the data sheet specifications recommend that applications limit the input current to 10 mA. If the supply is not capable of sinking the current, VIN can begin sourcing current to the operational amplifier and then take over as the source of positive supply voltage. The danger in this case is that the voltage can rise to levels that exceed the operational amplifier absolute maximum ratings. Another common question involves what happens to the amplifier if an input signal is applied to the input when the power supplies (V+ or V–) are at 0 V. Again, this question depends on the supply characteristic when at 0 V, or at a level below the input signal amplitude. If the supplies appear as high impedance, then the input source supplies the operational amplifier current through the current-steering diodes. This state is not a normal bias condition; most likely, the amplifier does not operate normally. If the supplies are low impedance, then the current through the steering diodes can become quite high. The current level depends on the ability of the input source to deliver current, and any resistance in the input path. If there is any uncertainty about the ability of the supply to absorb this current, add external Zener diodes to the supply pins; see Figure 32. Select the Zener voltage so that the diode does not turn on during normal operation. However, the Zener voltage must be low enough so that the Zener diode conducts if the supply pin begins to rise above the safe-operating, supply-voltage level. 7.3.3 EMI Rejection Ratio (EMIRR) The electromagnetic interference (EMI) rejection ratio, or EMIRR, describes the EMI immunity of operational amplifiers. An adverse effect that is common to many operational amplifiers is a change in the offset voltage as a result of RF signal rectification. An operational amplifier that is more efficient at rejecting this change in offset as a result of EMI has a higher EMIRR and is quantified by a decibel value. Measuring EMIRR can be performed in many ways, but this document provides the EMIRR IN+, which specifically describes the EMIRR performance when the RF signal is applied to the noninverting input pin of the operational amplifier. In general, only the noninverting input is tested for EMIRR for the following three reasons: • Operational amplifier input pins are known to be the most sensitive to EMI, and typically rectify RF signals better than the supply or output pins. • The noninverting and inverting operational amplifier inputs have symmetrical physical layouts and exhibit nearly matching EMIRR performance. • EMIRR is easier to measure on noninverting pins than on other pins because the noninverting input pin can be isolated on a printed-circuit-board (PCB). This isolation allows the RF signal to be applied directly to the noninverting input pin with no complex interactions from other components or connecting PCB traces. A more formal discussion of the EMIRR IN+ definition and test method is shown in the EMI Rejection Ratio of Operational Amplifiers application report, available for download at www.ti.com. The EMIRR IN+ of the OPA167x is plotted versus frequency in Figure 33. If available, any dual and quad operational amplifier device versions have approximately identical EMIRR IN+ performance. The OPA167x unitygain bandwidth is 16 MHz. EMIRR performance below this frequency denotes interfering signals that fall within the operational amplifier bandwidth. 16 Submit Documentation Feedback Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 OPA1678, OPA1679 www.ti.com SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 Feature Description (continued) 100 90 EMIRR IN+ (dB) 80 70 60 50 40 30 20 10 0 10 100 1000 10000 Frequency (MHz) C001 Figure 33. OPA167x EMIRR vs Frequency Table 1 lists the EMIRR IN+ values for the OPA167x at particular frequencies commonly encountered in realworld applications. Applications listed in Table 1 can be centered on or operated near the particular frequency shown. This information can be of special interest to designers working with these types of applications, or working in other fields likely to encounter RF interference from broad sources, such as the industrial, scientific, and medical (ISM) radio band. Table 1. OPA167x EMIRR IN+ for Frequencies of Interest FREQUENCY APPLICATION OR ALLOCATION EMIRR IN+ 400 MHz Mobile radio, mobile satellite, space operation, weather, radar, UHF 36 dB 900 MHz GSM, radio communication and navigation, GPS (to 1.6 GHz), ISM, aeronautical mobile, UHF 42 dB 1.8 GHz GSM, mobile personal comm. broadband, satellite, L-band 52 dB 2.4 GHz 802.11b/g/n, Bluetooth™, mobile personal comm., ISM, amateur radio and satellite, S-band 64 dB 3.6 GHz Radiolocation, aero comm./nav., satellite, mobile, S-band 67 dB 5 GHz 802.11a/n, aero communication and navigation, mobile communication, space and satellite operation, C-band 77 dB Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 Submit Documentation Feedback 17 OPA1678, OPA1679 SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 www.ti.com 7.3.3.1 EMIRR IN+ Test Configuration Figure 34 shows the circuit configuration for testing the EMIRR IN+. An RF source is connected to the operational amplifier noninverting input pin using a transmission line. The operational amplifier is configured in a unity-gain buffer topology with the output connected to a low-pass filter (LPF) and a digital multimeter (DMM). A large impedance mismatch at the operational amplifier input causes a voltage reflection; however, this effect is characterized and accounted for when determining the EMIRR IN+. The resulting dc offset voltage is sampled and measured by the multimeter. The LPF isolates the multimeter from residual RF signals that can interfere with multimeter accuracy. See the EMI Rejection Ratio of Operational Amplifiers application report for more details. Ambient temperature: 25Û& +VS ± 50 Low-Pass Filter + RF source DC Bias: 0 V Modulation: None (CW) Frequency Sweep: 201 pt. Log -VS Sample / Averaging Not shown: 0.1 µF and 10 µF supply decoupling Digital Multimeter Figure 34. EMIRR IN+ Test Configuration Schematic 7.4 Device Functional Modes 7.4.1 Operating Voltage The OPA167x series op amps operate from ±2.25 V to ±18 V supplies while maintaining excellent performance. The OPA167x series can operate with as little as 4.5 V between the supplies and with up to 36 V between the supplies. However, some applications do not require equal positive and negative output voltage swing. With the OPA167x series, power-supply voltages are not required to be equal. For example, the positive supply can be set to 25 V with the negative supply at –5 V. In all cases, the common-mode voltage must be maintained within the specified range. In addition, key parameters are ensured over the specified temperature range of TA = –40°C to +85°C. Parameters that vary significantly with operating voltage or temperature are shown in the Typical Characteristics section. 18 Submit Documentation Feedback Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 OPA1678, OPA1679 www.ti.com SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 8 Application and Implementation NOTE Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality. 8.1 Application Information 8.1.1 Capacitive Loads The dynamic characteristics of the OPA167x series are optimized for commonly encountered gains, loads, and operating conditions. The combination of low closed-loop gain and high capacitive loads decreases the phase margin of the amplifier and can lead to gain peaking or oscillations. As a result, heavier capacitive loads must be isolated from the output. The simplest way to achieve this isolation is to add a small resistor (RS equal to 50 Ω, for example) in series with the output. This small series resistor also prevents excess power dissipation if the output of the device becomes shorted. For more details about analysis techniques and application circuits, see the Feedback Plots Define Op Amp AC Performance application report, available for download from the TI website (www.ti.com). Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 Submit Documentation Feedback 19 OPA1678, OPA1679 SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 www.ti.com 8.2 Typical Application Contact microphones are useful for amplifying the sound of musical instruments which do not contain electrical pickups, such as acoustic guitars and violins. Most contact microphones use a piezo element to convert vibrations in the body of the musical instrument to a voltage which may be amplified or recorded. The low noise and low input bias current of the OPA1678 make the device an excellent choice for high impedance preamplifiers for piezo elements. This preamplifier circuit provides high input impedance for the piezo element but has low output impedance for driving long cable runs. The circuit is also designed to be powered from 48-V phantom power which is commonly available in professional microphone preamplifiers and recording consoles. A TINA-TI ™ simulation schematic of the circuit below is available in the Tools and Software section of the OPA167x product folder. R1 1.2 k C2 0.1 F R14 100 C1 22 F + ZD1 24 V ½ OPA1678 + ± VS+ VOUT VS± R7 2 k C5 22 F + R10 100 R3 1M R2 1.2 k R12 100 k R5 100 k TPD1E1B04 Piezo Contact Microphone R8 442 C3 390 pF C4 390 pF R6 100 k R11 100 R15 100 + R13 100 k R9 2 k R4 1M To Microphone Preamplifier C6 22 F ± + ½ OPA1678 Figure 35. Phantom-Powered Preamplifier for Piezo Contact Microphones 8.2.1 Design Requirements • –3-dB Bandwidth: 20 Hz to 20 kHz • Gain: 20 dB (10 V/V) • Piezo Element Capacitance: 8 nF (9-kHz resonance) 20 Submit Documentation Feedback Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 OPA1678, OPA1679 www.ti.com SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 Typical Application (continued) 8.2.2 Detailed Design Procedure 8.2.2.1 Power Supply In professional audio systems, phantom power is applied to the two signal lines that carry a differential audio signal from the microphone. Figure 36 is a diagram of the system showing 48-V phantom power applied to the differential signal lines between the piezo preamplifier output and the input of a professional microphone preamplifier. 6.8 k R1 R2 6.8 k 48 V Phantom Power + + Piezo Contact Microphone Differential Signal Cable ± ± Microphone Preamplifier Piezo Preamplifier Figure 36. System Diagram Showing the Application of Phantom Power to the Audio Signal Lines A voltage divider is used to extract the common-mode phantom power from the differential audio signal in this type of system. The voltage at center point of the voltage divider formed by R1 and R2 does not change when audio signals are present on the signal lines (assuming R1 and R2 are matched). A Zener diode forces the voltage at the center point of R1 and R2 to a regulated voltage. The values of R1 and R2 are determined by the allowable voltage drop across these resistors from the current delivered to both op amp channels and the Zener diode. There are two power supply current pathways in parallel, each sharing half the total current of the op amp and Zener diode. Resistors R1 and R2 can be calculated using Equation 1: R1 R2 RPS VZD I § OPA IZD · ¨ 2 2 ¸¹ © 6.8 k: RPS (1) A 24-V Zener diode is selected for this design, and 1 mA of current flows through the diode at idle conditions to maintain the reverse-biased condition of the Zener. The maximum idle power supply current of both op amp channels is 5 mA. Inserting these values into Equation 1 gives the values for R1 and R2 shown in Equation 2. 24V 24V 6.8 k: 6.8 k: 1.2 k: RPS § IOPA IZD · § 5.0 mA 1.0 mA · ¨ ¸ ¨ 2 2 2 2 ¸¹ © ¹ © (2) Using a value of 1.2 kΩ for resistors R1 and R2 establishes a 1-mA current through the Zener diode and properly regulate the node to 24 V. Capacitor C1 forms a low-pass filter with resistors R1 and R2 to filter the Zener diode noise and any residual differential audio signals. Mismatch in the values of R1 and R2 causes a portion of the audio signal to appear at the voltage divider center point. The corner frequency of the low-pass filter must be set below the audio band, as shown in Equation 3. 1 1 t t 13 PF o 22 PF C1 t 2 ˜ S ˜ R1 || R2 ˜ f 3dB 2 ˜ S ˜ 600 : ˜ 20 Hz (3) A 22-μF capacitor is selected because the capacitor meets the requirements for power supply filtering and is a widely available denomination. A 0.1-µF capacitor (C2) is added in parallel with C1 as a high-frequency bypass capacitor. Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 Submit Documentation Feedback 21 OPA1678, OPA1679 SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 www.ti.com Typical Application (continued) 8.2.2.2 Input Network Resistors R3 and R4 provide a pathway for the input bias current of the OPA1678 while maintaining the high input impedance of the circuit. The contact microphone capacitance and the required low-frequency response determine the values of R3 and R4. The –3-dB frequency formed by the microphone capacitance and amplifier input impedance is shown in Equation 4: 1 d 20 Hz F 3dB 2 ˜ S ˜ (R3 R4 ) ˜ CMIC (4) A piezo element with 8 nF of capacitance was selected for this design because the 9-kHz resonance is towards the upper end of the audible bandwidth, and is less likely to affect the frequency response of many musical instruments. The minimum value for resistors R3 and R4 is then calculated with Equation 5: R3 R 4 RIN RIN t 1 4 ˜ S ˜F t 3dB ˜ CMIC 1 t 497.4 k: 4 ˜ S ˜ 20 Hz ˜ 8 nF (5) 1-MΩ resistors are selected for R3 and R4 to ensure the circuit meets the design requirements for –3-dB bandwidth. The center point of resistors R3 and R4 is biased to half the supply voltage through the voltage divider formed by R5 and R6. This sets the input common-mode voltage of the circuit to a value within the input voltage range of the OPA1678. Piezo elements can produce very large voltages if the elements are struck with sufficient force. To prevent damage, the input of the OPA1678 is protected by a transient voltage suppressor (TVS) diode placed across the preamplifier inputs. The TPD1E1B04 TVS was selected due to low capacitance and the 6.4-V clamping voltage does not clamp the desired low amplitude vibration signals. Resistors R14 and R15 limit current flow into the amplifier inputs in the event that the internal protection diodes of the amplifier are forward-biased. 8.2.2.3 Gain R7, R8, and R9 determines the gain of the preamplifier circuit. The gain of the circuit is shown in Equation 6: R7 R9 AV 1 10 V/V R8 (6) Resistors R7 and R9 are selected with a value of 2 kΩ to avoid loading the output of the OPA1678 and producing distortion. The value of R8 is then calculated in Equation 7: R7 R9 2 k: 2 k: R8 444.4 : o 442 : AV 1 10 1 (7) Capacitors C3 and C4 limit the bandwidth of the circuit so that signals outside the audio bandwidth are not amplified. The corner frequency produced by capacitors C3 and C4 is shown in Equation 8. This corner frequency must be above the desired –3-dB bandwidth point to avoid attenuating high frequency audio signals. C3 C4 CFB CFB d 1 2 ˜ S ˜ F 3dB ˜ R7/9 d 1 d 3.98 nF 2 ˜ S ˜ 20 kHz ˜ 2 k: (8) 390-pF capacitors are selected for C3 and C4, which places the corner frequency approximately 1 decade above the desired –3-dB bandwidth point . Capacitors C3 and C4 must be NP0 or C0G type ceramic capacitors or film capacitors. Other ceramic dielectrics, such as X7R, are not suitable for these capacitors and produces distortion. 22 Submit Documentation Feedback Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 OPA1678, OPA1679 www.ti.com SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 Typical Application (continued) 8.2.2.4 Output Network The audio signal is AC-coupled onto the microphone signal lines through capacitors C5 and C6. The value of capacitors C5 and C6 are determined by the low-frequency design requirements and the input impedance of the microphone preamplifier that connect to the output of the circuit. Equation 9 shows an approximation of the capacitor value requirements, and neglects the effects of R10, R11, R12, and R13 on the frequency response. The microphone preamplifier input impedance (RIN_MIC) uses a typical value of 4.4 kΩ for the calculation. C5 C6 COUT COUT t 2 2 ˜ S ˜ RIN _ MIC ˜ 20 Hz t 2 t 3.6 PF 2 ˜ S ˜ 4.4 k: ˜ 20 Hz (9) For simplicity, the same 22-μF capacitors selected for the power supply filtering are selected for C5 and C6 to satisfy Equation 9. At least 50-V rated capacitors must be used for C5 and C6. If polarized capacitors are used, the positive terminal must be oriented towards the microphone preamplifier. Resistors R10 and R11 isolate the op amp outputs from the capacitances of long cables which may cause instability. R12 and R13 discharge ACcoupling capacitors C4 and C5 when phantom power is removed. 8.2.3 Application Curves The frequency response of the preamplifier circuit is shown in Figure 37. The –3-dB frequencies are 15.87 Hz and 181.1 kHz which meet the design requirements. The gain within the passband of the circuit is 18.9 dB, slightly below the design goal of 20 dB. The reduction in gain is a result of the voltage division between the output resistors of the piezo preamplifier circuit and the input impedance of the microphone preamplifier. The Aweighted noise of the circuit (referred to the input) is 842.2 nVRMS or –119.27 dBu. 20 19 18 17 Gain (dB) 16 15 14 13 12 11 10 10 100 1k 10k 100k 1M Frequency (Hz) C001 Figure 37. Frequency Response of the Preamplifier Circuit for a 8-nF Piezo Element 8.2.4 Other Applications The low noise and distortion of the OPA167x series make the devices designed for a variety of applications in professional and consumer audio products. The examples shown here are possible applications where the OPA167x provides exceptional performance. Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 Submit Documentation Feedback 23 OPA1678, OPA1679 SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 www.ti.com Typical Application (continued) 8.2.4.1 Phono Preamplifier for Moving Magnet Cartridges The noise and distortion performance of the OPA167x family of amplifiers is exceptional in applications with high source impedances, which makes these devices a viable choice in preamplifier circuits for moving magnet (MM) phono cartridges. Figure 38 shows a preamplifier circuit for MM cartridges with 40 dB of gain at 1 kHz. 15 V MM Phono Input R1 47 k V+ C1 150 pF V± R2 118 k R4 127 C2 27 nF + ½ OPA1678 ± VOUT -15 V R3 10 k R5 100 C5 100 F Output R6 100 k C3 7.5 nF C4 100 F Figure 38. Phono Preamplifier for Moving Magnet Cartridges (Single-Channel Shown) 8.2.4.2 Single-Supply Electret Microphone Preamplifier The preamplifier circuit shown in Figure 39 operates the OPA1678 as a transimpedance amplifier that converts the output current from the electret microphone's internal JFET into a voltage. Resistor R4 determines the gain of the circuit. Resistors R2 and R3 bias the input voltage to half the power supply voltage for proper functionality on a single-supply. C3 9V 16 pF R4 R1 13.7 k 61.9 k 9V C1 0.1 F 2.2 F Electret Microphone 9V R2 100 k ± Output + R3 100 k ½ OPA1678 C2 2.2 F Figure 39. Single-Supply Electret Microphone Preamplifier 8.2.4.3 Composite Headphone Amplifier Figure 40 shows the BUF634 buffer inside the feedback loop of the OPA1678 to increase the available output current for low-impedance headphones. If the BUF634 is used in wide-bandwidth mode, no additional components besides the feedback resistors are required to maintain loop stability. 24 Submit Documentation Feedback Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 OPA1678, OPA1679 www.ti.com SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 Typical Application (continued) 12 V 100 F 0.1 F 0.1 F + Input R1 100 k ½ OPA1678 BUF634 ± Output 0.1 F RBW 0.1 F 100 F -12 V R3 R2 200 200 Figure 40. Composite Headphone Amplifier (Single-Channel Shown) 8.2.4.4 Differential Line Receiver With AC-Coupled Outputs Figure 41 shows the OPA1678 used as an integrator that drives the reference pin of the INA1650, which forces the output DC voltage to 0 V. This configuration is an alternative to large AC-coupling capacitors which can distort at high output levels. The low input bias current and low input offset voltage of the OPA1678 make the device designed for integrator applications. 18 V -18 V C5 1 F C7 1 F R7 1M Input Differential Audio Signals C6 0.1 F C1 10 F C8 0.1 F 18 V R2 100 k XLR Connector R4 100 k 3 2 1 2 IN+ A OUT A 13 3 COM A REF A 12 C2 10 F 4 IN- A VMID(IN) 11 C3 10 F 5 IN- B VMID(OUT) 10 6 COM B REF B 9 7 IN+ B OUT B 8 ½ OPA1678 -18 V R6 1 M R5 100 k INA1650 C9 100 nF Output Single-Ended Audio Signals ½ OPA1678 ± 1 R3 1 M + 3 VEE 14 ± 2 1 VCC + R1 100 k C10 100 nF XLR Connector C4 10 F R8 1M Figure 41. Differential Line Receiver With AC-Coupled Outputs Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 Submit Documentation Feedback 25 OPA1678, OPA1679 SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 www.ti.com 9 Power Supply Recommendations The OPA167x devices are specified for operation from 4.5 V to 36 V (±2.25 V to ±18 V); many specifications apply from –40°C to +85°C. Parameters that can exhibit significant variance with regard to operating voltage or temperature are shown in the Typical Characteristics section. Applications with noisy or high-impedance power supplies require decoupling capacitors close to the device pins. In most cases, 0.1-µF capacitors are adequate. 10 Layout 10.1 Layout Guidelines For best operational performance of the device, use good printed-circuit board (PCB) layout practices, including: • Noise can propagate into analog circuitry through the power pins of the circuit as a whole and of op amp itself. Bypass capacitors are used to reduce the coupled noise by providing low-impedance power sources local to the analog circuitry. – Connect low-ESR, 0.1-µF ceramic bypass capacitors between each supply pin and ground, placed as close to the device as possible. A single bypass capacitor from V+ to ground is applicable for singlesupply applications. • Separate grounding for analog and digital portions of circuitry is one of the simplest and most-effective methods of noise suppression. One or more layers on multilayer PCBs are usually devoted to ground planes. A ground plane helps distribute heat and reduces electromagnetic interference (EMI) noise pickup. Physically separate digital and analog grounds, observing the flow of the ground current. • To reduce parasitic coupling, run the input traces as far away from the supply or output traces as possible. If these traces cannot be kept separate, crossing the sensitive trace perpendicular is much better as opposed to in parallel with the noisy trace. • Place the external components as close to the device as possible. As shown in Figure 42, keeping RF and RG close to the inverting input minimizes parasitic capacitance. • Keep the length of input traces as short as possible. Always remember that the input traces are the most sensitive part of the circuit. • Consider a driven, low-impedance guard ring around the critical traces. A guard ring can significantly reduce leakage currents from nearby traces that are at different potentials. • Cleaning the PCB following board assembly is recommended for best performance. • Any precision integrated circuit can experience performance shifts resulting from moisture ingress into the plastic package. Following any aqueous PCB cleaning process, baking the PCB assembly is recommended to remove moisture introduced into the device packaging during the cleaning process. A low temperature, postcleaning bake at 85°C for 30 minutes is sufficient for most circumstances. 26 Submit Documentation Feedback Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 OPA1678, OPA1679 www.ti.com SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 10.2 Layout Example + VIN A + VIN B VOUT A RG VOUT B RG RF RF (Schematic Representation) Place components close to device and to each other to reduce parasitic errors. Output A VS+ OUTPUT A Use low-ESR, ceramic bypass capacitor. Place as close to the device as possible. GND V+ RF Output B GND -IN A OUTPUT B +IN A -IN B RF RG VIN A GND RG V± Use low-ESR, ceramic bypass capacitor. Place as close to the device as possible. GND VS± +IN B Ground (GND) plane on another layer VIN B Keep input traces short and run the input traces as far away from the supply lines as possible. Figure 42. Operational Amplifier Board Layout for Noninverting Configuration 10.3 Power Dissipation The OPA167x series op amps are capable of driving 2-kΩ loads with a power-supply voltage up to ±18 V and full operating temperature range. Internal power dissipation increases when operating at high supply voltages. Copper leadframe construction used in the OPA167x series op amps improves heat dissipation compared to conventional materials. Circuit board layout can also help minimize junction temperature rise. Wide copper traces help dissipate the heat by acting as an additional heat sink. Temperature rise can be further minimized by soldering the devices to the circuit board rather than using a socket. Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 Submit Documentation Feedback 27 OPA1678, OPA1679 SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 www.ti.com 11 Device and Documentation Support 11.1 Device Support 11.1.1 Development Support 11.1.1.1 TINA-TI™ (Free Software Download) TINA™ is a simple, powerful, and easy-to-use circuit simulation program based on a SPICE engine. TINA-TI™ is a free, fully-functional version of the TINA software, preloaded with a library of macro models in addition to a range of both passive and active models. TINA-TI provides all the conventional DC, transient, and frequency domain analysis of SPICE, as well as additional design capabilities. Available as a free download from the WEBENCH ® Design Center, TINA-TI offers extensive post-processing capability that allows users to format results in a variety of ways. Virtual instruments offer the ability to select input waveforms and probe circuit nodes, voltages, and waveforms, creating a dynamic quick-start tool. NOTE These files require that either the TINA software (from DesignSoft™) or TINA-TI software be installed. Download the free TINA-TI software from the TINA-TI folder. 11.1.1.2 DIP Adapter EVM The DIP Adapter EVM tool provides an easy, low-cost way to prototype small surface mount devices. The evaluation tool these TI packages: D or U (SOIC-8), PW (TSSOP-8), DGK (VSSOP-8), DBV (SOT-23-6, SOT-235 and SOT-23-3), DCK (SC70-6 and SC70-5), and DRL (SOT563-6). The DIP Adapter EVM may also be used with terminal strips or may be wired directly to existing circuits. 11.1.1.3 Universal Operational Amplifier EVM The Universal Op Amp EVM is a series of general-purpose, blank circuit boards that simplify prototyping circuits for a variety of device package types. The evaluation module board design allows many different circuits to be constructed easily and quickly. Five models are offered, with each model intended for a specific package type. PDIP, SOIC, VSSOP, TSSOP and SOT-23 packages are all supported. NOTE These boards are unpopulated, so users must provide their own devices. TI recommends requesting several op amp device samples when ordering the Universal Op Amp EVM. 11.1.1.4 TI Precision Designs TI Precision Designs are analog solutions created by TI’s precision analog applications experts and offer the theory of operation, component selection, simulation, complete PCB schematic and layout, bill of materials, and measured performance of many useful circuits. TI Precision Designs are available online at http://www.ti.com/ww/en/analog/precision-designs/. 11.1.1.5 WEBENCH® Filter Designer WEBENCH® Filter Designer is a simple, powerful, and easy-to-use active filter design program. The WEBENCH Filter Designer allows the user to create optimized filter designs using a selection of TI operational amplifiers and passive components from TI's vendor partners. Available as a web-based tool from the WEBENCH® Design Center, WEBENCH® Filter Designer allows the user to design, optimize, and simulate complete multistage active filter solutions within minutes. 28 Submit Documentation Feedback Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 OPA1678, OPA1679 www.ti.com SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 11.2 Documentation Support 11.2.1 Related Documentation The following documents are relevant to using the OPA167x, and are recommended for reference. All are available for download at www.ti.com unless otherwise noted. • Texas Instruments, Source resistance and noise considerations in amplifiers • Texas Instruments, Single-Supply Operation of Operational Amplifiers • Texas Instruments, Op Amp Performance Analysis • Texas Instruments, Compensate Transimpedance Amplifiers Intuitively • Texas Instruments, Tuning in Amplifiers • Texas Instruments, Feedback Plots Define Op Amp AC Performance • Texas Instruments, Active Volume Control for Professional Audio 11.3 Related Links The table below lists quick access links. Categories include technical documents, support and community resources, tools and software, and quick access to order now. Table 2. Related Links PARTS PRODUCT FOLDER ORDER NOW TECHNICAL DOCUMENTS TOOLS & SOFTWARE SUPPORT & COMMUNITY OPA1678 Click here Click here Click here Click here Click here OPA1679 Click here Click here Click here Click here Click here 11.4 Receiving Notification of Documentation Updates To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper right corner, click on Alert me to register and receive a weekly digest of any product information that has changed. For change details, review the revision history included in any revised document. 11.5 Community Resource The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of Use. TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help solve problems with fellow engineers. Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and contact information for technical support. 11.6 Trademarks TINA-TI, E2E are trademarks of Texas Instruments. WEBENCH is a registered trademark of Texas Instruments. TINA, DesignSoft are trademarks of DesignSoft, Inc. is a trademark of ~ Texas Instruments. is a registered trademark of ~ Texas Instruments. 11.7 Electrostatic Discharge Caution These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. 11.8 Glossary SLYZ022 — TI Glossary. This glossary lists and explains terms, acronyms, and definitions. Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 Submit Documentation Feedback 29 OPA1678, OPA1679 SBOS855A – FEBRUARY 2017 – REVISED MAY 2018 www.ti.com 12 Mechanical, Packaging, and Orderable Information The following pages include mechanical, packaging, and orderable information. This information is the most current data available for the designated devices. This data is subject to change without notice and revision of this document. For browser-based versions of this data sheet, refer to the left-hand navigation. 30 Submit Documentation Feedback Copyright © 2017–2018, Texas Instruments Incorporated Product Folder Links: OPA1678 OPA1679 PACKAGE OPTION ADDENDUM www.ti.com 16-May-2018 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (°C) Device Marking (4/5) OPA1678IDGKR ACTIVE VSSOP DGK 8 2500 Green (RoHS & no Sb/Br) CU NIPDAUAG Level-2-260C-1 YEAR -40 to 85 1AW7 OPA1678IDGKT ACTIVE VSSOP DGK 8 250 Green (RoHS & no Sb/Br) CU NIPDAUAG Level-2-260C-1 YEAR -40 to 85 1AW7 OPA1678IDR ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 OP1678 OPA1678IDRGR ACTIVE SON DRG 8 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 OP1678 OPA1678IDRGT ACTIVE SON DRG 8 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 OP1678 OPA1679IDR ACTIVE SOIC D 14 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA1679 OPA1679IPWR ACTIVE TSSOP PW 14 2000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA1679 (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based flame retardants must also meet the <=1000ppm threshold requirement. (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 16-May-2018 (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. 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Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 30-Apr-2018 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing OPA1678IDGKR VSSOP DGK 8 OPA1678IDGKT VSSOP DGK OPA1678IDR SOIC D OPA1678IDRGR SON OPA1678IDRGT SON SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 2500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 8 250 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 8 2500 330.0 12.4 6.4 5.2 2.1 8.0 12.0 Q1 DRG 8 3000 330.0 12.4 3.3 3.3 1.1 8.0 12.0 Q2 DRG 8 250 180.0 12.4 3.3 3.3 1.1 8.0 12.0 Q2 OPA1679IDR SOIC D 14 2500 330.0 16.4 6.5 9.0 2.1 8.0 16.0 Q1 OPA1679IPWR TSSOP PW 14 2000 330.0 12.4 6.9 5.6 1.6 8.0 12.0 Q1 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 30-Apr-2018 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) OPA1678IDGKR VSSOP DGK 8 2500 366.0 364.0 50.0 OPA1678IDGKT VSSOP DGK 8 250 366.0 364.0 50.0 OPA1678IDR SOIC D 8 2500 367.0 367.0 35.0 OPA1678IDRGR SON DRG 8 3000 367.0 367.0 35.0 OPA1678IDRGT SON DRG 8 250 210.0 185.0 35.0 OPA1679IDR SOIC D 14 2500 367.0 367.0 38.0 OPA1679IPWR TSSOP PW 14 2000 367.0 367.0 35.0 Pack Materials-Page 2 IMPORTANT NOTICE Texas Instruments Incorporated (TI) reserves the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. 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