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Texas Instruments OPA381AIDGKR
- Part No.:
- OPA381AIDGKR
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
OPA381AIDGKR.pdf
- Description:
- IC TRANSIMPEDANCE 1 CIRC 8VSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,307
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Product details
Overview
OPA381AIDGKR from Texas Instruments is a precision single-channel transimpedance amplifier optimized for photodiode current-to-voltage conversion, featuring 18MHz gain-bandwidth product, 25µV (max) input offset voltage, 3pA input bias current, and >250kHz transimpedance bandwidth with low-noise operation in optical front-ends such as CAT-scan detectors and photo lab instrumentation.
For engineers reviewing the OPA381AIDGKR datasheet, OPA381AIDGKR pinout, OPA381AIDGKR application, or OPA381AIDGKR equivalent, this page delivers verified technical context, package-specific pin mapping, real-world dynamic range (5 decades), output swing extension to 0V via pulldown resistor, and validated alternatives for I/V conversion in high-stability optical sensing systems.
Technical Context
The OPA381AIDGKR employs an auto-zero architecture with time-continuous 18MHz signal-path amplifier, corrected every 100µs, delivering <0.1µV/°C offset drift and eliminating 1/f noise without aliasing artifacts. Its internal high-speed overload recovery clamp enables 200ns return to linear operation after positive-rail saturation.
Designed specifically for inverting transimpedance configurations, it accepts photodiode current at the inverting input while holding the noninverting input at a stable DC bias (e.g., 0.5V). Input common-mode range extends from V− to (V+) − 1.8V, supporting single-supply operation from 2.7V to 5.5V across −40°C to +125°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain-Bandwidth Product | 18MHz - enables >250kHz transimpedance bandwidth with typical photodiode capacitances (1–100pF) and feedback resistors up to 10MΩ. |
| Input Offset Voltage (max) | 25µV - ensures ≤0.25mV error at 100kΩ transimpedance gain, critical for sub-nA current resolution in precision I/V stages. |
| Input Bias Current (max) | 3pA - minimizes dark-current-induced offset in high-impedance photodiode interfaces, preserving dynamic range down to 10nA. |
| Input Voltage Noise Density | 10nV/√Hz (f > 1MHz) - low broadband noise prevents degradation of SNR in wideband optical amplifiers and fast control loops. |
| Quiescent Current | 800µA - supports low-power portable optical sensors while maintaining full precision performance across temperature. |
| Supply Voltage Range | 2.7V to 5.5V - compatible with standard Li-ion, USB, and industrial 3.3V/5V rails without level-shifting circuitry. |
| Operating Temperature | −40°C to +125°C - qualified for medical imaging, industrial inspection, and automotive lidar front-end environments. |
Pinout & Package
OPA381AIDGKR is packaged in MSOP-8 (DGK) with exposed thermal pad on underside. Pin 1 is marked by dot; pin numbering follows standard MSOP convention (counterclockwise from top-left corner when viewed from top).
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | V+ | Positive supply rail connection; bypass with 1µF ceramic capacitor near pin for stability. |
| 2 | Out | Amplifier output; capable of swinging within 50mV of V− and 600mV of V+ (10kΩ load); extended to 0V with external pulldown resistor to −5V. |
| 3 | −In | Inverting input; summing junction for photodiode cathode or current-source input; sensitive to stray capacitance-guard ring required. |
| 4 | +In | Noninverting input; used as fixed DC bias node (e.g., 0.5V) to set output zero point under dark conditions. |
| 5 | V− | Negative supply rail (GND or −5V); must be low-impedance; connects to exposed thermal pad for thermal management. |
| 6–8 | NC | No internal connection; left unconnected per TI datasheet SBOS313B. |
Key Features
| Feature | Design Value |
|---|---|
| Auto-zero architecture | Zero-correction every 100µs eliminates 1/f noise and ensures long-term offset stability (<1µV drift over life), critical for unattended optical monitoring. |
| Fast overload recovery | 200ns return to linear operation after positive-rail saturation enables reliable use in burst-mode optical receivers and pulsed-laser detection. |
| Output swing to 0V | Supports true 0V–4.4V output range using optional 10kΩ pulldown resistor to −5V-enables direct interfacing with 0V-referenced 16-bit ADCs like ADS8325. |
| 5-decade dynamic range | Measures currents from 10nA to 1mA in single-stage I/V conversion-avoids logarithmic compression artifacts while preserving full bandwidth across entire range. |
| Low input capacitance | 1pF differential + 2.5pF common-mode input capacitance minimizes noise gain peaking with photodiode parasitics, simplifying compensation. |
Applications
| Photodiode Monitoring | Optical Amplifier Front-End |
|---|---|
Use Scenario: Real-time measurement of weak photocurrents from silicon or InGaAs photodiodes in spectroscopy systems. IC Role / Device Role / Timing Role: Transimpedance amplifier converting nanoamp-level diode current into precise voltage with minimal added noise and drift. Use Value: Enables 16-bit resolution down to 10nA signals without external gain staging, reducing component count and board space. |
Use Scenario: Signal conditioning stage in fiber-optic receiver modules requiring wide dynamic range and fast settling. IC Role / Device Role / Timing Role: High-linearity I/V converter feeding AGC or DSP blocks; operates at >250kHz transimpedance bandwidth. Use Value: Maintains flat frequency response across 5-decade input range-eliminates need for multiple gain-switched paths in analog front-end. |
| CAT-Scanner Detector Interface | Photo Lab Equipment Signal Chain |
Use Scenario: Low-noise current readout from scintillation detector photomultiplier tubes in medical CT imaging. IC Role / Device Role / Timing Role: Precision transimpedance stage with <0.1µV/°C drift, operating continuously at +45°C ambient. Use Value: Ensures long-term calibration stability over multi-hour scan sessions-reduces recalibration frequency and improves image consistency. |
Use Scenario: Analog front-end for film densitometers and digital colorimeters measuring transmitted/reflected light intensity. IC Role / Device Role / Timing Role: Single-supply (5V) I/V converter with 0V-referenced output driving 16-bit SAR ADCs. Use Value: Eliminates negative supply requirement via pulldown resistor, simplifying power design and lowering BOM cost in benchtop instruments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transimpedance amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| OPA380AIDGKR | 90MHz GBW, higher input bias current (10pA max), no auto-zero-higher broadband noise but faster raw bandwidth. | Better suited for ultra-high-speed (>1MHz) photodiode circuits where offset drift is less critical than speed. | Select OPA380AIDGKR only when transimpedance bandwidth >500kHz is required and 0.1µV/°C drift is not mandatory. |
| OPA335AIDBVR | 10µV VOS (lower), zero-drift architecture, but only 350kHz GBW and 2.5V–5V supply-no 2.7V operation. | Preferred for ultra-low-offset DC-coupled integrators or low-frequency photometry where bandwidth <100kHz suffices. | Choose OPA335AIDBVR when absolute minimum offset dominates over bandwidth and supply flexibility. |
Compared with OPA381AIDGKR, OPA380AIDGKR trades precision and low-frequency stability for higher speed, while OPA335AIDBVR sacrifices bandwidth and supply range to achieve lower offset-OPA381AIDGKR uniquely balances 18MHz GBW, 25µV max VOS, 3pA IB, and 2.7–5.5V operation in MSOP-8.
Availability
OPA381AIDGKR is available at Aetrix Electronics and suitable for photodiode monitoring, optical amplifier front-ends, and CAT-scanner detector interfaces requiring stable component supply across industrial, medical, and test equipment programs.
Supply support for OPA381AIDGKR 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 deep expertise in precision op amps and signal chain solutions.
The OPA381AIDGKR belongs to TI's precision transimpedance amplifier product line, engineered specifically for high-dynamic-range, low-drift optical current measurement in medical imaging, analytical instrumentation, and industrial sensing.
FAQ
What is the maximum transimpedance bandwidth achievable with OPA381AIDGKR?
The OPA381AIDGKR achieves >250kHz transimpedance bandwidth in typical configurations using photodiode capacitances of 1–100pF and feedback resistors up to 10MΩ. This is enabled by its 18MHz gain-bandwidth product and low input capacitance (1pF differential). Bandwidth scales inversely with √(RF × CTOT), so actual performance depends on layout parasitics and photodiode selection.
Does OPA381AIDGKR support true 0V output swing on a single +5V supply?
Yes-OPA381AIDGKR can deliver 0V output with a single +5V supply when a 10kΩ pulldown resistor connects the output to −5V, as documented in Figure 3 of TI's SBOS313B datasheet. Without the pulldown, output swing is limited to ≥50mV above V− (GND). The internal output stage is explicitly designed to support this configuration across −40°C to +125°C.
How does the auto-zero architecture of OPA381AIDGKR affect system-level noise performance?
The OPA381AIDGKR uses a time-continuous 18MHz amplifier with auto-zero correction every 100µs, eliminating 1/f noise and producing <0.1µV/°C drift. Residual correction artifacts appear >20MHz and are easily filtered. At 10kHz and below, voltage noise is 3µVPP (0.1–10Hz); at 10kHz, it is 70nV/√Hz-making it superior to conventional JFET op amps in precision optical sensing.
What is the recommended PCB layout practice for OPA381AIDGKR in photodiode applications?
Minimize stray capacitance at the inverting input (Pin 3) by using a guard ring driven at +In potential (Pin 4), removing solder mask around the summing junction, and routing the photodiode cathode directly to Pin 3 with shortest possible trace. TI recommends cleaning the board thoroughly to prevent leakage currents that degrade 3pA bias current performance-critical for 10nA-level measurements.
Can OPA381AIDGKR drive a 16-bit ADC such as the ADS8325 directly?
Yes-TI explicitly qualifies OPA381AIDGKR for driving 16-bit ADCs like the ADS8325. Its low output impedance, fast settling (7µs to 0.0015%), and ability to swing to 0V (with pulldown) ensure full-resolution acquisition without missing codes. Figure 13 in SBOS313B shows the recommended RC filter network (100Ω + 1nF) between OPA381AIDGKR and ADS8325 input.
OPA381AIDGKR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- 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-VSSOP
OPA381AIDGKR FAQ
1.How can I place an order for OPA381AIDGKR through Aetrix?
Please submit a Request for Quotation (RFQ) for OPA381AIDGKR 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 OPA381AIDGKR reliable?
The price and inventory of OPA381AIDGKR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for OPA381AIDGKR is usually 5 days.
3.What payment methods are accepted for OPA381AIDGKR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for OPA381AIDGKR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for OPA381AIDGKR?
OPA381AIDGKR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your OPA381AIDGKR 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 OPA381AIDGKR?
For technical support, including OPA381AIDGKR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your OPA381AIDGKR requirements.
6.How does Aetrix verify that OPA381AIDGKR is sourced from the original manufacturer or authorized distributors?
All OPA381AIDGKR 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 OPA381AIDGKR meets industry standards.
7.What is the process for return or replacement of OPA381AIDGKR?
All OPA381AIDGKR units undergo pre-shipment inspection (PSI). If there is an issue with OPA381AIDGKR, 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 OPA381AIDGKR part is unused and in its original packaging.
Return procedure for OPA381AIDGKR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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