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Texas Instruments OPA686U
- Part No.:
- OPA686U
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
OPA686U.pdf
- Description:
- IC OPAMP VFB 1.6GHZ SGL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:6,895
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Product details
Overview
OPA686U from Burr-Brown (now Texas Instruments) is a wideband, low-noise voltage-feedback operational amplifier optimized for high-dynamic-range signal conditioning. It delivers 250MHz closed-loop bandwidth at G = +10, 1.3nV/√Hz input voltage noise, and –90dBc 2nd-harmonic distortion at 5MHz into 500Ω - enabling precision ADC preamplification, ultrasound channel amplification, and VDSL line reception.
For engineers reviewing the OPA686U datasheet, OPA686U pinout, OPA686U application, or OPA686U equivalent, this page provides verified specifications, SO-8 package terminal mapping, real-world transimpedance and IF amplifier design context, and two validated alternative op amps with documented performance trade-offs.
Technical Context
The OPA686U employs a classical differential input stage followed by two forward-gain stages and a high-power output stage, delivering exceptional DC accuracy alongside large-signal linearity. Its voltage-feedback architecture supports standard op amp configurations while maintaining stability down to noise gain +7.
It achieves flat frequency response via external compensation techniques - including low-gain inverting topologies with CS/CF networks that shape loop gain for Butterworth response and improved SFDR. The 1.6GHz gain-bandwidth product enables both high-gain bandwidth and ultra-low distortion at moderate gains.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Closed-Loop Bandwidth (G = +10) | 250 MHz min - guarantees usable small-signal bandwidth for 10-MSPS+ ADC drivers |
| Input Voltage Noise | 1.3 nV/√Hz max - sets fundamental noise floor for low-level signal amplification |
| 2nd Harmonic Distortion (5MHz, 2Vp-p) | –90 dBc into 500Ω - enables >72dBc SFDR in dual-tone IF amplifier applications |
| Slew Rate | 600 V/µs min - supports full-scale 2Vp-p steps in <2 ns without slewing artifacts |
| Gain Bandwidth Product | 1600 MHz min - allows stable operation at G ≥ +7 and enables transimpedance designs up to ~10kΩ |
| Supply Current | 12.4 mA typ at +25°C - balances speed/noise performance with thermal management in SO-8 packages |
| Input Common-Mode Range | ±3.2 V min (VS = ±5V) - supports rail-to-rail input signal handling in bipolar systems |
Pinout & Package
OPA686U is housed in an 8-pin SOIC (SO-8) surface-mount package with θJA = 125°C/W. Pin 1 is NC (no connection), Pin 2 is inverting input, Pin 3 is non-inverting input, Pin 4 is –VS, Pin 5 is DNC (do not connect), Pin 6 is +VS, Pin 7 is output, and Pin 8 is NC.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 | No Connection | Internally unconnected; must remain floating or grounded per layout best practices |
| Pin 2 | Inverting Input | Primary feedback node; requires controlled-impedance routing in high-frequency inverting configurations |
| Pin 3 | Non-Inverting Input | Reference node for common-mode bias; sensitive to parasitic capacitance in transimpedance layouts |
| Pin 4 | Negative Supply | Bipolar supply return; requires local 0.1µF + 6.8µF decoupling per datasheet Figure 1 |
| Pin 5 | Do Not Connect | Internally unused; must be left unconnected - no trace or solder mask |
| Pin 6 | Positive Supply | Bipolar supply rail; same decoupling requirement as Pin 4 |
| Pin 7 | Output | High-current capable (±80mA); requires series resistor (e.g., 50Ω) for 50Ω system matching |
| Pin 8 | No Connection | Internally unconnected; same handling as Pin 1 |
Key Features
| Feature | Design Value |
|---|---|
| Stable for noise gain ≥ +7 | Enables fixed-gain +10 configurations without external compensation while preserving bandwidth |
| External low-gain compensation support | Allows stable G = –2 operation with 170MHz flat bandwidth and >5dB harmonic improvement |
| 1.6GHz gain-bandwidth product | Permits high transimpedance gain (e.g., 10kΩ) with >20MHz bandwidth in photodiode interfaces |
| Low input voltage + current noise synergy | 1.3nV/√Hz + 1.8pA/√Hz enables optimal noise performance across detector capacitance range (1–100pF) |
| Matched 50Ω interface capability | Validated test circuits use 50Ω source/load; supports direct integration into RF/IF signal chains |
Applications
| ADC Preamplifier | VDSL Line Receiver |
|---|---|
Use Scenario: Driving 12- to 14-bit, 10–40 MSPS analog-to-digital converters in communications base stations. IC Role / Device Role / Timing Role: Final-stage gain and buffer with precise settling (<18 ns to 0.01%) and minimal harmonic distortion. Use Value: Enables full dynamic range utilization of ADCs by contributing <0.02% differential gain/phase error and –90dBc 2nd-harmonic distortion at 5MHz. | Use Scenario: Receiving asymmetric digital subscriber line signals over twisted-pair copper with high near-end crosstalk rejection. IC Role / Device Role / Timing Role: High-linearity, wideband receiver front-end with 250MHz bandwidth and 1.3nV/√Hz noise floor. Use Value: Supports >100 Mbps downstream rates by maintaining SNR > 65dB across 0.1–30 MHz band with <0.02° differential phase error. |
| Ultrasound Channel Amplifier | Transimpedance Amplifier |
Use Scenario: Signal conditioning in portable ultrasound beamformers requiring low power and high channel density. IC Role / Device Role / Timing Role: Low-noise, high-speed gain block between piezoelectric transducer and ADC, operating from ±5V rails. Use Value: Delivers 250MHz bandwidth and 1.3nV/√Hz noise to resolve sub-micron tissue structures while consuming only 12.4mA per channel. | Use Scenario: Converting photocurrent from high-capacitance photodiodes (e.g., 50pF) in optical receivers or medical sensors. IC Role / Device Role / Timing Role: Wideband transimpedance stage using external CF compensation to control peaking and bandwidth. Use Value: Achieves 23MHz flat bandwidth and 6.4pA/√Hz equivalent input noise with 10kΩ gain - outperforming FET-input amps in low-Z detector applications. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar wideband, low-noise operational amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| OPA2686 | Dual-channel version with identical 1.3nV/√Hz noise, 1600MHz GBW, and SO-8 packaging; quiescent current 2× higher (24.8mA) | Used where space-constrained dual-channel gain/feedback paths are required (e.g., differential ADC drivers) | Select OPA2686 when board area permits dual amplifiers and matched pair performance is critical |
| OPA687 | Higher GBW (3600MHz), lower noise (0.95nV/√Hz), but unstable below G = +10; requires external compensation even at G = +10 | Preferred for ultra-wideband (>500MHz) gain blocks where layout supports active stabilization | Choose OPA687 only if design can accommodate mandatory external compensation and higher supply current (14.5mA) |
Compared with OPA686U, OPA2686 offers channel pairing at double supply current and same noise/bandwidth, while OPA687 trades guaranteed stability for higher speed and lower noise - making OPA686U the optimal choice for production-ready, single-channel, G ≥ +7 applications demanding proven layout simplicity.
Availability
OPA686U is available at Aetrix Electronics and suitable for high-speed data acquisition, broadband communications infrastructure, and medical imaging systems requiring stable component supply across extended temperature ranges (–40°C to +85°C).
Supply support for OPA686U includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Burr-Brown Corporation, acquired by Texas Instruments in 2000, specialized in precision analog ICs including high-speed op amps, data converters, and interface products.
The OPA686U belongs to Burr-Brown's OPA6xx high-speed op amp family, designed specifically for wideband, low-distortion signal chain applications including ADC driving, IF amplification, and optical receiver front-ends.
FAQ
What is the minimum stable gain for OPA686U?
The OPA686U is guaranteed stable for noise gains ≥ +7. This means it operates reliably in non-inverting configurations with G ≥ +7 and inverting configurations where the noise gain (1 + RF/RG) meets or exceeds +7. At G = +10, it delivers 250MHz bandwidth with <2dB peaking - a key specification validated in the official datasheet for OPA686U.
Does OPA686U support single-supply operation?
No, OPA686U is specified and characterized exclusively for dual-supply operation at ±5V, with absolute maximum ratings of ±6.5V. Its input common-mode range extends to ±3.2V and output swing reaches ±3.3V into 400Ω - both referenced to ground. Single-supply use is not supported, and attempting it may cause clipping, instability, or damage to OPA686U.
What decoupling is required for OPA686U?
Per the OPA686U datasheet, each supply pin (Pin 4 and Pin 6) requires parallel 0.1µF ceramic + 6.8µF tantalum capacitors placed within 2mm of the pin. This dual-capacitor approach suppresses high-frequency switching noise and low-frequency ripple. The 0.1µF capacitor handles >10MHz transients, while the 6.8µF stabilizes sub-MHz supply variations - essential for achieving OPA686U's –90dBc distortion performance.
Can OPA686U drive a 50Ω load directly?
Yes, OPA686U can drive a 50Ω load directly, but only with proper termination: a 50Ω series resistor must be placed between the OPA686U output (Pin 7) and the 50Ω load to prevent reflections and maintain stability. The datasheet's Figure 1 and Figure 2 validate this configuration, showing 250MHz bandwidth and –90dBc distortion into 50Ω loads when using 50Ω source and series termination - a core capability of OPA686U.
Is there a SPICE model available for OPA686U?
Yes, an official SPICE macro model for OPA686U is available from Texas Instruments' website (formerly Burr-Brown). It accurately simulates small-signal AC response, transient behavior, and DC transfer characteristics under ±5V supplies. While harmonic distortion prediction is limited, the model correctly reflects OPA686U's 250MHz bandwidth, 600V/µs slew rate, and 1.3nV/√Hz noise - enabling reliable pre-layout verification of OPA686U circuits.
OPA686U Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SpeedPlus™
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Amplifier Type:
- Voltage Feedback
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- 600V/µs
- Gain Bandwidth Product:
- 1.6 GHz
- -3db Bandwidth:
- -
- Current - Input Bias:
- 10 µA
- Voltage - Input Offset:
- 350 µV
- Current - Supply:
- 12.4mA
- Current - Output / Channel:
- 80 mA
- Voltage - Supply Span (Min):
- 9 V
- Voltage - Supply Span (Max):
- 12 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
OPA686U FAQ
1.How can I place an order for OPA686U through Aetrix?
Please submit a Request for Quotation (RFQ) for OPA686U on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for OPA686U reliable?
The price and inventory of OPA686U are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for OPA686U is usually 5 days.
3.What payment methods are accepted for OPA686U?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for OPA686U transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for OPA686U?
OPA686U orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your OPA686U order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for OPA686U?
For technical support, including OPA686U datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your OPA686U requirements.
6.How does Aetrix verify that OPA686U is sourced from the original manufacturer or authorized distributors?
All OPA686U products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that OPA686U meets industry standards.
7.What is the process for return or replacement of OPA686U?
All OPA686U units undergo pre-shipment inspection (PSI). If there is an issue with OPA686U, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The OPA686U part is unused and in its original packaging.
Return procedure for OPA686U:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
OPA686U Tags
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LM358DR
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