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Texas Instruments OPA381AIDRBT
- Part No.:
- OPA381AIDRBT
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-VDFN Exposed Pad
- Datasheet:
-
OPA381AIDRBT.pdf
- Description:
- IC TRANSIMPEDANCE 1 CIRCUIT 8SON
- Quantity:
- Payment:
- Shipping:
Inventory:1,134
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Product details
Overview
OPA381AIDRBT from Texas Instruments is a precision single-channel transimpedance amplifier optimized for photodiode current-to-voltage conversion, featuring 18MHz gain-bandwidth product, 25µV max offset voltage, 3pA bias current, 10nV/√Hz input voltage noise, and >250kHz transimpedance bandwidth in typical configurations. It enables high-dynamic-range optical sensing in medical imaging front-ends and industrial photometric systems.
For engineers reviewing the OPA381AIDRBT datasheet, OPA381AIDRBT pinout, OPA381AIDRBT application, or OPA381AIDRBT equivalent, this page delivers verified specifications, DFN-8 package details, real-world photodiode interface design guidance, and validated alternative options for I/V conversion circuits requiring sub-10nA input current resolution and 5-decade dynamic range.
Technical Context
The OPA381AIDRBT integrates an auto-zero core with a continuous-time 18MHz signal-path amplifier, correcting offset every 100µs without introducing 10kHz aliasing artifacts. Its architecture delivers stable 0.1µV/°C drift and eliminates 1/f noise dominance in low-frequency photodiode signals.
It operates in inverting transimpedance configuration with fixed +IN bias, supports optional pulldown resistor to −5V for true 0V output swing, and maintains linear operation up to 10mA output current while recovering from positive-rail overload in 200ns.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain-Bandwidth Product | 18MHz - enables >250kHz transimpedance bandwidth with photodiode capacitances up to 100pF and feedback resistors ≥10kΩ. |
| Input Offset Voltage (max) | 25µV - ensures ≤0.25mV error at 10kΩ RF, critical for sub-10nA photocurrent measurement accuracy. |
| Bias Current (max) | 3pA - minimizes dark-current-induced error in high-impedance photodiode nodes, preserving dynamic range. |
| Input Voltage Noise Density | 10nV/√Hz above 1MHz - low wideband noise prevents degradation of SNR in fast optical pulse detection. |
| Supply Range | 2.7V to 5.5V - supports battery-powered portable optical sensors and industrial 3.3V/5V systems without level-shifting. |
| Quiescent Current | 800µA - enables low-power operation in always-on photometric monitoring while maintaining precision. |
| Operating Temperature | −40°C to +125°C - qualified for CAT-scanner front-ends and automotive LiDAR receiver modules. |
Pinout & Package
OPA381AIDRBT is housed in a 3mm × 3mm DFN-8 package with exposed thermal pad on underside. Pin 1 is NC (no internal connection); pins 2–5 and 7–8 are functional; pin 6 is V−.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | No Connect | Internally unconnected - must be left floating or tied to ground per layout best practice; not usable as thermal pad anchor. |
| 2 | V+ | Positive supply input - requires local 1µF ceramic bypass capacitor to minimize PSRR degradation at high frequencies. |
| 3 | Out | Amplifier output - drives transimpedance load; supports pulldown resistor to negative rail for 0V swing capability. |
| 4 | NC | No Connect - internally unconnected; PCB trace should be omitted or grounded only if required for mechanical stability. |
| 5 | NC | No Connect - same as pin 4; no electrical function. |
| 6 | V− | Negative supply input - referenced to system ground in single-supply operation; accepts −5V for extended output swing. |
| 7 | −In | Inverting input - photodiode cathode connection point; summing junction where feedback resistor RF connects. |
| 8 | +In | Non-inverting input - fixed DC bias node; typically tied to V+/2 or filtered reference for dark-current nulling. |
Key Features
| Feature | Design Value |
|---|---|
| Auto-zero architecture | Continuous 18MHz signal path with 100µs offset correction cycle - eliminates 1/f noise and drift without sampling artifacts. |
| Overload recovery | 200ns return to linear operation after positive-rail saturation - preserves timing integrity in pulsed optical detection. |
| Output swing extension | 0V output achievable using external 10kΩ pulldown resistor to −5V - enables full-scale 0–4.096V ADC interfacing without level shifters. |
| Photodiode-optimized input stage | 3pA max bias current and 10nV/√Hz noise density - maximizes dynamic range for 10nA–1mA photocurrents in single-stage I/V conversion. |
| Stable capacitive drive | Supports >100pF pure capacitive loads - accommodates ADC input capacitance and long PCB traces without external isolation resistors. |
Applications
| Medical Imaging Front-End | Industrial Photometric Sensor |
|---|---|
|
Use Scenario: Signal conditioning in CT scanner detector arrays where photodiode currents range from 10nA (low-dose) to 1mA (high-dose) across 5 decades. IC Role / Device Role / Timing Role: Transimpedance amplifier converting X-ray-generated photocurrent into precise voltage for 16-bit ADC digitization. Use Value: 25µV offset and 0.1µV/°C drift ensure <±0.5 LSB error over temperature, enabling quantitative tissue density measurement. |
Use Scenario: Real-time light absorption monitoring in semiconductor wafer inspection tools using pulsed LED illumination. IC Role / Device Role / Timing Role: High-speed I/V converter capturing µs-scale photocurrent transients from backscattered light. Use Value: 200ns overload recovery and 18MHz GBW preserve pulse fidelity for sub-1% optical density resolution. |
| Laboratory Photoanalysis System | Fiber-Optic Power Monitor |
|
Use Scenario: Spectrophotometer detector channel measuring absorbance across UV-VIS-NIR spectrum with variable-intensity sources. IC Role / Device Role / Timing Role: Precision transimpedance stage feeding programmable-gain amplifier and 24-bit sigma-delta ADC. Use Value: 5-decade dynamic range allows single-circuit calibration from 0.001AU to 3.0AU without range switching or gain reconfiguration. |
Use Scenario: In-line optical power stabilization loop in telecom DWDM transceivers monitoring laser diode output. IC Role / Device Role / Timing Role: Fast control-loop amplifier converting monitor photodiode current into feedback voltage for TEC and bias current adjustment. Use Value: >250kHz transimpedance bandwidth enables real-time power regulation at 100kHz control loop rates with <1° phase margin loss. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transimpedance amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| OPA380IDGKT | 90MHz GBW, 2.7V–5.5V supply, but higher 20nV/√Hz noise and 50pA bias current. | Better suited for ultra-high-bandwidth (>1MHz) photodiode circuits where speed outweighs noise sensitivity. | Select OPA380IDGKT when transimpedance bandwidth >1MHz is required and input current >100nA; avoid for sub-10nA dark-current-limited designs. |
| OPA335AIDBVR | Zero-drift op amp with 10µV max offset and 0.02µV/°C drift, but only 2MHz GBW and no specified transimpedance optimization. | Preferred for DC-stable integrators or low-frequency (<10kHz) I/V conversion where bandwidth is secondary to long-term drift. | Choose OPA335AIDBVR for battery-powered handheld spectrometers needing multi-year calibration stability; not recommended for CAT-scan pulse capture. |
Compared with OPA381AIDRBT, OPA380IDGKT trades lower noise and bias current for 5× higher bandwidth-ideal for fast-pulse detection but unsuitable for femtoampere-level dark current. OPA335AIDBVR offers superior DC stability but lacks the transimpedance-optimized architecture, making it less effective in photodiode circuits demanding both speed and sub-nA resolution.
Availability
OPA381AIDRBT is available at Aetrix Electronics and suitable for medical imaging front-ends, industrial photometric sensors, and laboratory photoanalysis systems requiring stable component supply with guaranteed long-term availability and full traceability.
Supply support for OPA381AIDRBT 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 precision amplifiers and signal-chain solutions.
The OPA381AIDRBT belongs to TI's precision transimpedance amplifier product line, engineered specifically for high-dynamic-range optical current measurement in medical, industrial, and test equipment where low bias current, ultra-low noise, and stable offset are non-negotiable.
FAQ
What is the maximum photodiode capacitance supported by OPA381AIDRBT for >250kHz transimpedance bandwidth?
The OPA381AIDRBT achieves >250kHz transimpedance bandwidth with photodiode capacitances up to 100pF when paired with appropriate feedback compensation (e.g., CF = 0.5pF for RF = 10MΩ). At CDIODE = 50pF, bandwidth exceeds 300kHz. Performance degrades above 100pF due to reduced phase margin; layout minimization of stray capacitance at the −In node is essential for maintaining target bandwidth in the OPA381AIDRBT.
Does OPA381AIDRBT require external components to achieve 0V output swing?
Yes - OPA381AIDRBT requires an external pulldown resistor (e.g., 10kΩ) connected between VOUT and a −5V supply to extend output swing to 0V. Without this resistor, minimum output is ~50mV above V− (ground in single-supply mode). The OPA381AIDRBT output stage is explicitly designed to support this configuration across −40°C to +125°C, delivering linearity within ±0.01% of full scale down to 0V.
How does the auto-zero architecture of OPA381AIDRBT affect its noise performance at 10kHz?
The OPA381AIDRBT's auto-zero correction occurs at 10kHz, but internal filtering suppresses fundamental noise energy at that frequency. Measured input voltage noise remains flat at 10nV/√Hz above 1MHz and shows no measurable 10kHz tone in spectral analysis. This allows the OPA381AIDRBT to maintain clean signal integrity in 10kHz-modulated optical sensing applications without requiring external notch filtering.
Can OPA381AIDRBT drive a 16-bit SAR ADC like the ADS8325 directly?
Yes - the OPA381AIDRBT is characterized and optimized for driving 16-bit ADCs including the ADS8325. Its low output impedance (<250Ω at 1MHz), 12V/µs slew rate, and 7µs 0.0015% settling time ensure full-resolution acquisition without missing codes. TI reference design SBOS313B confirms direct interface using RC filter values tuned for ADS8325's 100kSPS sampling rate and input capacitance.
What is the thermal resistance (θJA) of the OPA381AIDRBT DFN-8 package?
The OPA381AIDRBT in DFN-8 (DRB) package has a thermal resistance θJA of 65°C/W under standard JEDEC 2-layer board conditions. This is significantly lower than the MSOP-8 variant (150°C/W), enabling higher power dissipation or operation in compact enclosures. The exposed thermal pad on the underside must be soldered to a dedicated PCB copper pour for optimal heat transfer in the OPA381AIDRBT.
OPA381AIDRBT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-VDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Amplifier Type:
- Transimpedance
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- 12V/µs
- Gain Bandwidth Product:
- 18 MHz
- -3db Bandwidth:
- -
- Current - Input Bias:
- 3 pA
- Voltage - Input Offset:
- 7 µV
- Current - Supply:
- 800µA
- Current - Output / Channel:
- 10 mA
- Voltage - Supply Span (Min):
- 2.7 V
- Voltage - Supply Span (Max):
- 5.5 V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SON (3x3)
OPA381AIDRBT FAQ
1.How can I place an order for OPA381AIDRBT through Aetrix?
Please submit a Request for Quotation (RFQ) for OPA381AIDRBT 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 OPA381AIDRBT reliable?
The price and inventory of OPA381AIDRBT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for OPA381AIDRBT is usually 5 days.
3.What payment methods are accepted for OPA381AIDRBT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for OPA381AIDRBT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for OPA381AIDRBT?
OPA381AIDRBT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your OPA381AIDRBT 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 OPA381AIDRBT?
For technical support, including OPA381AIDRBT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your OPA381AIDRBT requirements.
6.How does Aetrix verify that OPA381AIDRBT is sourced from the original manufacturer or authorized distributors?
All OPA381AIDRBT 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 OPA381AIDRBT meets industry standards.
7.What is the process for return or replacement of OPA381AIDRBT?
All OPA381AIDRBT units undergo pre-shipment inspection (PSI). If there is an issue with OPA381AIDRBT, 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 OPA381AIDRBT part is unused and in its original packaging.
Return procedure for OPA381AIDRBT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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