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Texas Instruments OPA656N/250
- Part No.:
- OPA656N/250
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- SC-74A, SOT-753
- Datasheet:
-
OPA656N/250.pdf
- Description:
- IC OPAMP VFB 1 CIRCUIT SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,000
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Product details
Overview
OPA656N/250 from Texas Instruments is a unity-gain stable, FET-input voltage-feedback operational amplifier optimized for transimpedance and high-speed data acquisition front-ends. It delivers 550MHz unity-gain bandwidth, 6nV/√Hz input voltage noise, and ±2pA input bias current, enabling precision optical signal conditioning in photodiode-based OTDR and oscilloscope front-ends.
For engineers reviewing the OPA656N/250 datasheet, OPA656N/250 pinout, OPA656N/250 application, or OPA656N/250 equivalent, key selection criteria include its JFET-input low-noise performance at high closed-loop gain, stability on ±5V supplies, and validated transimpedance bandwidth up to 4MHz with 100kΩ feedback.
Technical Context
The OPA656N/250 employs a complementary bipolar JFET-input process to achieve ultra-low input voltage noise (6nV/√Hz) while maintaining unity-gain stability - a rare combination enabling wideband transimpedance amplification without external compensation. Its 230MHz gain-bandwidth product supports high closed-loop gains with flat frequency response up to 50MHz (0.1dB flatness).
Designed for dual-supply operation (±5V nominal), it features rail-to-rail output swing (±3.5V into 100Ω), 400V/µs slew rate, and harmonic distortion of –80dBc (HD2) and –100dBc (HD3) at 5MHz with 2VPP output into 200Ω - critical for test-and-measurement signal fidelity.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Unity-gain bandwidth | 550MHz - enables stable buffer operation at full small-signal bandwidth without peaking or oscillation. |
| Gain-bandwidth product | 230MHz - defines maximum achievable closed-loop bandwidth at higher gains (e.g., 46MHz at G = +5V/V). |
| Input voltage noise | 6nV/√Hz - minimizes integrated noise in transimpedance applications where diode capacitance dominates noise gain. |
| Input bias current | ±2pA (max) - preserves DC accuracy in high-impedance photodiode and sensor interfaces without significant offset drift. |
| Supply voltage range | ±5V nominal (±6V absolute max) - supports industrial-grade dual-rail operation with 11.7–16.7mA quiescent current. |
| Large-signal bandwidth | 150MHz (2VPP) - ensures faithful reproduction of fast transient signals in active probes and digitizer front-ends. |
| Harmonic distortion (HD2/HD3) | –80dBc / –100dBc at 5MHz - meets spectral purity requirements for optical communication and spectrum analysis front-ends. |
Pinout & Package
OPA656N/250 is packaged in an 8-pin SOIC (D package), 4.9mm × 6mm body size, with exposed pad not present. Pin functions are validated per TI SBOS196I Rev. FEBRUARY 2024.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 5, 8 | No connect (NC) | Internally unconnected; must be left floating or tied to ground per layout best practice - no electrical function. |
| 2 | VIN– | Inverting input - primary node for feedback network connection in transimpedance and inverting configurations. |
| 3 | VIN+ | Noninverting input - used for reference biasing or grounded in inverting mode; low input bias current minimizes offset error. |
| 4 | –VS | Negative supply rail - requires local 0.1μF + 6.8μF decoupling; thermal resistance RθJA = 123°C/W (SOIC). |
| 6 | VOUT | Amplifier output - drives 100Ω loads to ±3.5V; closed-loop output impedance <0.01Ω at 100kHz. |
| 7 | +VS | Positive supply rail - symmetric dual supply required for specified AC/DC performance; ESD protected to ±2000V HBM. |
Key Features
| Feature | Design Value |
|---|---|
| Unity-gain stable architecture | Eliminates need for external compensation in photodiode TIA and unity-gain buffer designs - reduces BOM count and layout sensitivity. |
| JFET-input stage | Delivers 6nV/√Hz voltage noise and ±2pA input bias current - essential for high-gain, low-current optical detection with minimal added noise. |
| High DC precision | ±0.6mV max input offset voltage and ±6μV/°C drift - maintains accuracy across –40°C to +85°C industrial temperature range. |
| Low distortion at high frequency | –100dBc HD3 at 5MHz into 200Ω - preserves signal integrity in test equipment front-ends requiring clean spectral content. |
| Wide supply range compatibility | Operates from ±5V to ±6V - supports both standard lab bench supplies and compact ±6V systems without regulation overhead. |
Applications
| Optical Time-Domain Reflectometry (OTDR) | Oscilloscope Front-End Amplifier |
|---|---|
|
Use Scenario: Detecting weak, time-resolved backscatter pulses from fiber-optic cables over distances up to 100km. IC Role / Device Role / Timing Role: Transimpedance amplifier converting photodiode current to high-fidelity voltage signal with >4MHz bandwidth and sub-pA/√Hz input-referred noise. Use Value: Enables 10cm spatial resolution via 1ns pulse response and 550MHz small-signal bandwidth - directly supporting IEEE 802.3ah PON diagnostics. |
Use Scenario: Conditioning fast analog signals before ADC sampling in 1GHz-class digital storage oscilloscopes. IC Role / Device Role / Timing Role: Unity-gain buffer and gain-stage amplifier providing 550MHz bandwidth, 400V/µs slew rate, and –100dBc HD3 at 5MHz. Use Value: Preserves rise time (<1.3ns) and harmonic fidelity for accurate waveform reconstruction - critical for jitter analysis and serial data compliance testing. |
| Active Probe Signal Conditioning | Medical Laser Pulse Detection |
|
Use Scenario: High-impedance, low-capacitance signal acquisition from DUTs in automated test equipment. IC Role / Device Role / Timing Role: Low-noise, high-Z input buffer driving 50Ω coaxial cable with minimal loading and phase shift. Use Value: Achieves 150MHz large-signal bandwidth at 2VPP while maintaining <0.1dB gain flatness to 50MHz - ensuring probe calibration traceability. |
Use Scenario: Converting nanosecond laser diode return pulses in flow cytometry and blood oximetry sensors. IC Role / Device Role / Timing Role: Wideband transimpedance amplifier with 100kΩ gain and 0.5pF feedback capacitor for 4MHz bandwidth. Use Value: Delivers 0.40pA/√Hz input-referred current noise - enabling detection of single-photon-level events in low-light biomedical imaging. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-speed, low-noise op-amp applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| OPA814 | Higher GBW (250MHz), lower voltage noise (5.3nV/√Hz), but higher input bias current (±5pA). | Better suited for ultra-low-noise, moderate-impedance (>10kΩ) transimpedance designs where bias current is less critical. | Select OPA814 when 5.3nV/√Hz noise and 750V/µs slew rate outweigh need for sub-2pA bias current. |
| OPA659 | Higher GBW (350MHz), higher voltage noise (8.9nV/√Hz), wider supply range (±6.5V), and higher quiescent current (22mA). | Preferred for >500MHz small-signal bandwidth needs where noise floor is secondary to speed. | Choose OPA659 only when 350MHz GBW is mandatory and system can accommodate 8.9nV/√Hz noise and 22mA IQ. |
Compared with OPA656N/250, OPA814 offers superior noise and slew rate but trades off input bias current; OPA659 delivers higher bandwidth at the cost of increased noise and power - making OPA656N/250 the optimal balance for precision transimpedance and test-equipment front-ends demanding <6nV/√Hz and ±2pA.
Availability
OPA656N/250 is available at Aetrix Electronics and suitable for optical time-domain reflectometry (OTDR), oscilloscope front-end amplification, and active probe signal conditioning requiring stable component supply across industrial temperature ranges and long-lifecycle production programs.
Supply support for OPA656N/250 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 expertise in high-performance op-amps and precision signal-chain solutions.
The OPA656N/250 belongs to TI's OPA high-speed precision op-amp family, engineered specifically for transimpedance amplification, optical test equipment, and high-fidelity data acquisition where low noise, unity-gain stability, and dc accuracy are co-required.
FAQ
What is the maximum recommended supply voltage for OPA656N/250?
The OPA656N/250 has an absolute maximum supply voltage rating of ±6.5V, but its recommended operating range is ±5V to ±6V. Operation at ±6V is supported across the full –40°C to +85°C industrial temperature range, delivering specified AC and DC performance including 550MHz unity-gain bandwidth and ±0.6mV input offset voltage. Exceeding ±6.5V risks permanent damage per TI SBOS196I Absolute Maximum Ratings.
Can OPA656N/250 be used in single-supply configurations?
Yes, OPA656N/250 supports single-supply operation with appropriate input/output biasing. Its input common-mode range extends to within 2.1V of the negative rail and 2.75V below the positive rail at 25°C, and its output swings to within 1.3V of each rail into 100Ω. For reliable single-supply use, set VCM near mid-supply (e.g., 2.5V on +5V rail) and ensure input signals remain within CMIR limits - verified in TI's SBOS196I Section 6.5.
What is the typical input capacitance of OPA656N/250, and why does it matter in transimpedance designs?
The OPA656N/250 exhibits 2.6pF differential-mode and 0.4pF common-mode input capacitance (total ~3pF), plus ~0.3pF PCB parasitic. This capacitance interacts with photodiode junction capacitance to form a pole that limits transimpedance bandwidth. In a 100kΩ TIA design, total input capacitance determines required feedback capacitor (e.g., 0.5pF) to achieve Butterworth response - directly impacting bandwidth and stability per TI Application Note SBOS196I Section 8.2.
How does OPA656N/250 achieve unity-gain stability with a JFET input?
OPA656N/250 integrates internal compensation tailored for its JFET-input, voltage-feedback architecture - achieving 550MHz unity-gain bandwidth without external components. Unlike uncompensated JFET op-amps, its dominant-pole compensation ensures phase margin >60° at G = +1, validated by open-loop gain/phase plots (Figure 6-19) and small-signal step response (Figure 6-5) in TI SBOS196I. This eliminates risk of oscillation in photodiode TIA and unity-gain buffer layouts.
Is OPA656N/250 suitable for driving 50Ω transmission lines directly?
Yes, OPA656N/250 is characterized driving 100Ω loads (equivalent to two 50Ω terminations in parallel) with ±3.5V swing and <1.3ns rise time. Its closed-loop output impedance is <0.01Ω at 100kHz, and harmonic distortion remains –100dBc (HD3) at 5MHz into 200Ω - confirming robust 50Ω line-driving capability. For optimal matching, use series termination at the output per TI's Figure 8-1 test circuit.
OPA656N/250 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Amplifier Type:
- Voltage Feedback
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- 295V/µs
- Gain Bandwidth Product:
- 230 MHz
- -3db Bandwidth:
- 500 MHz
- Current - Input Bias:
- 2 pA
- Voltage - Input Offset:
- 250 µV
- Current - Supply:
- 14mA
- Current - Output / Channel:
- 70 mA
- Voltage - Supply Span (Min):
- 8 V
- Voltage - Supply Span (Max):
- 12 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-5
OPA656N/250 FAQ
1.How can I place an order for OPA656N/250 through Aetrix?
Please submit a Request for Quotation (RFQ) for OPA656N/250 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 OPA656N/250 reliable?
The price and inventory of OPA656N/250 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for OPA656N/250 is usually 5 days.
3.What payment methods are accepted for OPA656N/250?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for OPA656N/250 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for OPA656N/250?
OPA656N/250 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your OPA656N/250 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 OPA656N/250?
For technical support, including OPA656N/250 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your OPA656N/250 requirements.
6.How does Aetrix verify that OPA656N/250 is sourced from the original manufacturer or authorized distributors?
All OPA656N/250 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 OPA656N/250 meets industry standards.
7.What is the process for return or replacement of OPA656N/250?
All OPA656N/250 units undergo pre-shipment inspection (PSI). If there is an issue with OPA656N/250, 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 OPA656N/250 part is unused and in its original packaging.
Return procedure for OPA656N/250:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
OPA656N/250 Tags
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