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Texas Instruments OPA2681U
- Part No.:
- OPA2681U
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
OPA2681U.pdf
- Description:
- IC OPAMP CFB 280MHZ DUAL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,540
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Product details
Overview
OPA2681U from Texas Instruments is a dual wideband current-feedback operational amplifier with disable control, designed for high-speed single-supply operation. It delivers 225MHz bandwidth (G = +2), 2100V/µs slew rate, ±4.0V output swing, and 150mA output current at only 6mA per channel quiescent supply current - enabling RGB line driving and single-supply ADC input buffering in portable instrumentation and broadband video systems.
For engineers reviewing the OPA2681U datasheet, OPA2681U pinout, OPA2681U application, or OPA2681U equivalent, key selection considerations include its SO-8 package, dual-channel current-feedback architecture, guaranteed 150MHz large-signal bandwidth on +5V supply, enable/disable timing (25ns/100ns), and differential gain/phase performance suitable for NTSC video.
Technical Context
The OPA2681U employs a current-feedback topology with transimpedance gain (ZOL) of 100kΩ, enabling bandwidth that remains stable across gains (+1 to +10). Its output stage delivers high current with minimal voltage headroom - sustaining ±3.9V swing into 100Ω on ±5V supplies and 1V–4V swing into 100Ω on +5V supply - while maintaining low crossover distortion.
It features an integrated disable function (SO-14 only) with 25ns enable time and 100ns disable time, reducing supply current to <400µA per channel when disabled. The device operates over –40°C to +85°C and is specified for both ±5V bipolar and +5V single-supply configurations, with input common-mode range extending to ±3.5V (±5V supply) or 1.5V–3.5V (+5V supply).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Small-Signal Bandwidth (G = +2) | 225MHz on +5V supply - supports >100MHz video signal paths without gain-dependent bandwidth loss. |
| Slew Rate | 2100V/µs (±5V) / 830V/µs (+5V) - enables clean 2V-step response in ≤2ns for high-fidelity pulse amplification. |
| Output Current (Sourcing) | +190mA (±5V, no load); +150mA (+5V, VS/2 load) - drives 75Ω video cables or 100Ω ADC inputs directly. |
| Supply Current per Channel | 6mA (±5V, 25°C, trimmed) - enables dual-channel high-speed amplification with <13mA total quiescent draw. |
| Disable Current | <400µA per channel (low-disable state) - reduces system power by >95% during video MUX channel idle periods. |
| Input Voltage Noise | 2.2nV/√Hz (>1MHz) - preserves SNR in wideband imaging and RF IF chain applications. |
| Differential Gain/Phase (NTSC) | 0.001%/0.01° (RL = 150Ω) - meets broadcast-grade video fidelity requirements without external calibration. |
Pinout & Package
OPA2681U is housed in an SO-8 surface-mount package (Package Drawing 182), with thermal resistance θJA = 125°C/W. Pin functions are validated per TI SBOS091A datasheet Figure 6 (Top View).
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | –In A | Inverting input for Channel A; requires matched feedback network for stable current-feedback operation. |
| 2 | +In A | Non-inverting input for Channel A; high-impedance node (100kΩ || 2pF) used for DC biasing in single-supply designs. |
| 3 | –VS | Negative supply rail (or ground in single-supply mode); must be decoupled with 0.1µF capacitor near pin. |
| 4 | +VS | Positive supply rail (±5V or +5V); optional 0.1µF capacitor between +VS and –VS improves 2nd harmonic distortion by 3–6dB. |
| 5 | Out A | Amplified output for Channel A; capable of sourcing/sinking >150mA with <1V headroom to rails. |
| 6 | Out B | Amplified output for Channel B; electrically isolated but thermally coupled to Out A for matched performance. |
| 7 | +In B | Non-inverting input for Channel B; identical impedance and biasing requirements as +In A. |
| 8 | –In B | Inverting input for Channel B; independent feedback path required; not internally connected to –In A. |
Key Features
| Feature | Design Value |
|---|---|
| Wideband current-feedback architecture | Bandwidth varies <10% from G = +1 (280MHz) to G = +10 (125MHz), enabling consistent high-frequency response across gain settings. |
| Single-supply optimized output stage | Delivers 3Vp-p output swing with >150MHz bandwidth on +5V supply - eliminates need for negative rail in portable video/ADC drivers. |
| Low-distortion high-current drive | –79dBc 2nd harmonic (5MHz, 2Vp-p, RL = 100Ω) and <0.001% differential gain error - meets NTSC/PAL broadcast linearity specs. |
| Fast enable/disable control | 25ns enable / 100ns disable timing with <±50mV turn-on glitch - enables sub-microsecond video channel switching in wired-OR multiplexers. |
| Trimmed quiescent current | 6mA/ch at 25°C with low drift (±40µV/°C offset drift) - guarantees power budget compliance across industrial temperature range. |
Applications
| RGB Line Driver | Differential ADC Input Driver |
|---|---|
|
Use Scenario: Driving three parallel 75Ω coaxial cables from graphics controller DAC outputs in embedded displays. IC Role / Device Role / Timing Role: Dual-channel OPA2681U buffers R/G/B signals simultaneously with matched gain/phase and <10ps inter-channel skew. Use Value: 0.001% differential gain and 0.01° phase error preserve color fidelity; 225MHz bandwidth supports UXGA (1600×1200@60Hz) pixel clocks. |
Use Scenario: Conditioning single-ended sensor signals into differential inputs of 10-bit, 60MSPS ADC (e.g., ADS823) in portable test equipment. IC Role / Device Role / Timing Role: One OPA2681U channel provides DC bias (2.5V), the other implements G = +10 differential driver with transformer-coupled input. Use Value: >150MHz full-scale input bandwidth and –72dBc harmonic distortion ensure >9 effective bits at 20MHz input frequency. |
| Wired-OR Video Multiplexer | High-Speed Active Filter Stage |
|
Use Scenario: Selecting between two camera inputs onto one HD-SDI transmission line in security DVR systems using make-before-break switching. IC Role / Device Role / Timing Role: Two OPA2681U channels (e.g., OPA2681N in SO-14) share a common 75Ω output node; DIS pins sequenced for glitch-free transition. Use Value: <20mV switching glitch and 70dB off-isolation prevent crosstalk; 65dB off-isolation at 5MHz ensures clean channel separation. |
Use Scenario: Implementing 20MHz 2nd-order Butterworth low-pass filtering in ultrasound front-end analog signal chains. IC Role / Device Role / Timing Role: First OPA2681U channel acts as unity-gain buffer and DC level shifter; second provides G = +4 AC gain with minimal phase shift. Use Value: Constant bandwidth vs gain enables precise pole placement; 0.03Ω closed-loop output impedance prevents filter Q degradation from source impedance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar wideband current-feedback op amp applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| OPA2680U | Voltage-feedback architecture; unity-gain stable; 280MHz GBW; 1900V/µs slew rate; higher DC accuracy (±0.5mV VOS). | Better for precision DC-coupled gain blocks where bandwidth stability across gain is less critical than offset/CMRR. | Select OPA2680U when DC accuracy (e.g., <100µV VOS drift) outweighs absolute bandwidth; avoid for >G=+5 video gain stages. |
| LMH6720MA | Current-feedback; 280MHz small-signal BW (G=+2); 3000V/µs slew rate; higher supply current (10mA/ch); no disable pin. | Preferred for ultra-high-slew applications (e.g., pulsed laser drivers) where power efficiency and channel disable are secondary. | Choose LMH6720MA when >2500V/µs slew is mandatory and SO-8 disable functionality is unnecessary; verify thermal derating at 125°C/W θJA. |
Compared with OPA2681U, OPA2680U trades bandwidth flatness for superior DC precision, while LMH6720MA delivers higher slew at increased quiescent power and without disable control - making OPA2681U optimal for battery-powered video/ADC interfaces requiring dynamic power gating.
Availability
OPA2681U is available at Aetrix Electronics and suitable for RGB line driving, differential ADC input conditioning, and wired-OR video multiplexing requiring stable component supply across industrial temperature ranges and long production lifecycles.
Supply support for OPA2681U 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
Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of innovation in high-speed op amps and data converters.
The OPA2681U belongs to TI's OPA26xx current-feedback op amp family, engineered specifically for wideband video, communications, and instrumentation applications demanding high output current, low distortion, and single-supply operability.
FAQ
What is the maximum operating voltage for the OPA2681U?
The OPA2681U has an absolute maximum supply voltage rating of ±6.5VDC. Its specified operating range is ±5V for dual-supply use and +5V for single-supply operation, with maximum single-supply voltage rated at 12V. Operation beyond ±6.5V risks permanent damage; sustained operation above 12V on +5V configuration violates guaranteed specifications and may cause thermal runaway due to internal power dissipation limits.
Does the OPA2681U support true rail-to-rail input and output?
The OPA2681U is not a rail-to-rail device. Its input common-mode range extends to ±3.5V on ±5V supplies (i.e., 1V from each rail), and its output swing is specified as ±3.9V into 100Ω (±5V) or 1V–4V on +5V supply. While it achieves exceptional headroom for a wideband current-feedback op amp, it requires ≥1V of margin to either supply rail for linear operation - confirmed by test data showing degraded distortion beyond these limits.
Is the disable function available on the OPA2681U (SO-8) package?
No - the disable (DIS) pin is only present on the OPA2681N (SO-14) variant, as explicitly stated in the datasheet: "DISABLE (Disabled Low) (SO-14 only)". The OPA2681U in SO-8 lacks this pin and therefore cannot be placed into low-power disable mode. System-level power savings must be implemented externally (e.g., via supply switching) when using the OPA2681U.
What is the typical harmonic distortion performance of the OPA2681U at 5MHz?
At 5MHz, 2Vp-p output, and 100Ω load, the OPA2681U delivers –79dBc 2nd harmonic and –74dBc 3rd harmonic distortion under ±5V supply conditions. On +5V supply, the same conditions yield –70dBc (2nd) and –72dBc (3rd) - values verified in SBOS091A Section "AC PERFORMANCE" tables and confirmed by Figure 6–7 distortion plots. Performance degrades predictably with increasing load capacitance or decreasing supply voltage.
Can the OPA2681U drive a 50Ω load directly?
Yes - the OPA2681U is characterized into 100Ω loads but can drive 50Ω loads with verified performance: sourcing +190mA and sinking –150mA (±5V, no load) ensures robust 50Ω operation. However, output swing compresses to ±3.7V (min) into 50Ω, and thermal considerations require PCB layout attention - the SO-8 package's θJA = 125°C/W necessitates adequate copper pour and airflow for sustained 50Ω drive at full bandwidth.
OPA2681U 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:
- Current Feedback
- Number of Circuits:
- 2
- Output Type:
- -
- Slew Rate:
- 2100V/µs
- Gain Bandwidth Product:
- -
- -3db Bandwidth:
- 280 MHz
- Current - Input Bias:
- 30 µA
- Voltage - Input Offset:
- 1.3 mV
- Current - Supply:
- 12mA (x2 Channels)
- Current - Output / Channel:
- 190 mA
- Voltage - Supply Span (Min):
- 5 V
- Voltage - Supply Span (Max):
- 12 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
OPA2681U FAQ
1.How can I place an order for OPA2681U through Aetrix?
Please submit a Request for Quotation (RFQ) for OPA2681U 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 OPA2681U reliable?
The price and inventory of OPA2681U are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for OPA2681U is usually 5 days.
3.What payment methods are accepted for OPA2681U?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for OPA2681U transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for OPA2681U?
OPA2681U orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your OPA2681U 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 OPA2681U?
For technical support, including OPA2681U datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your OPA2681U requirements.
6.How does Aetrix verify that OPA2681U is sourced from the original manufacturer or authorized distributors?
All OPA2681U 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 OPA2681U meets industry standards.
7.What is the process for return or replacement of OPA2681U?
All OPA2681U units undergo pre-shipment inspection (PSI). If there is an issue with OPA2681U, 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 OPA2681U part is unused and in its original packaging.
Return procedure for OPA2681U:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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