OPA2277UA - 10µV Dual Precision Op Amp | Texas Instruments
MPN: OPA2277UA ✓ نشطOPA2277UA نظرة عامة
Background knowledge: A precision op-amp (operational amplifier) is a high-gain DC-coupled analog building block whose input offset voltage, offset drift, bias current, and noise are engineered to far tighter limits than those of a general-purpose op-amp. Within the signal-chain hierarchy, the OPA2277 sits in the "precision" tier between general-purpose amplifiers (e.g. OPA234) and zero-dr chopper-stabilized amplifiers (e.g. OPA2188), drawing meaningfully lower bias current than old bipolar parts (e.g. OP-27) while delivering lower voltage noise than early CMOS parts (e.g. TLC2277). It is functionally a "dual, improved OP-177" intended for bridge amplifiers, strain gauges, thermocouple conditioning, and precision active filters where µV-level DC accuracy must be preserved across -40°C to +125°C.
Architecturally, the OPA2277 uses a bipolar transistor input stage with laser-trimmed thin-film resistors, a complementary bipolar output stage capable of driving 2 kΩ loads, and internal compensation that removes the need for an external compensation capacitor. The result is a stable unity-gain device that does not oscillate when used as a buffer, with a gain-bandwidth product of 1 MHz and a 2 V/µs slew rate that supports audio-bandwidth signal conditioning, 16-bit ADC input buffers, and reference-voltage buffers.
Typical applications include precision weighing scales and load-cell signal chains (where 10 µV Vos preserves mV-level bridge outputs), industrial process-control 4-20 mA loop transmitters, medical instrumentation front-ends, precision active filters, multi-channel data-acquisition multiplexed front ends, and reference-voltage buffers for 16-bit and 18-bit ADCs. The wide supply range also allows use in ±15 V legacy industrial backplanes.
A practical design consideration: although the OPA2277 is unity-gain stable, its 1 MHz GBW means it is best used for DC-accurate low-frequency applications (sub-100 kHz). For higher-bandwidth precision needs, the OPA2227 (same package, 13 MHz GBW) or OPA2156 (pin-compatible, lower noise) are better choices; choose this part when DC accuracy and price dominate over bandwidth. This page synthesizes distributor stock and pricing, AEO-optimized FAQ, and drop-in alternatives that complement the manufacturer datasheet.
بدائل مباشرة لـ OPA2277UA — نفس الحزمة، متوافق دبوس بدبوس. تُستثنى القطع ذات الحزم المختلفة التي تتطلب تعديل PCB.
الطرازات في هذه السلسلة
طرازات من نفس السلسلة متوافقة تمامًا مع OPA2277UA (نفس عامل الشكل والبصمة) — يختلف في Package, Amplifier Type, Slew Rate, Supply Voltage Range, Operating Temperature Range.
OPA2227UA
✅ بديل مباشر📋 بديل مرجعي (غير موجود في الكتالوج)
OPA2277UA/2K5
✅ بديل مباشر📋 بديل مرجعي (غير موجود في الكتالوج)
OPA2277UA الحدود القصوى والخصائص الكهربائية
| Number of Channels | 2 (Dual) |
| Amplifier Type | Precision Operational Amplifier |
| Input Offset Voltage (max) | 10 µV |
| Offset Drift (typ) | ±0.1 µV/°C |
| Open-Loop Gain (min) | 134 dB |
| Common-Mode Rejection (min) | 140 dB |
| Power-Supply Rejection (min) | 130 dB |
| Quiescent Current per Channel (typ) | 800 µA |
| Supply Voltage Range | ±2 V to ±18 V |
| Supply Voltage (Single) | 4 V to 36 V |
| Gain-Bandwidth Product | 1 MHz |
| Slew Rate | 2 V/µs |
| Output Swing (RL=2 kΩ, ±15V) | ±14 V (within 1 V of rails) |
| نطاق درجة حرارة التشغيل | -40°C to +125°C |
| العلبة | 8-pin SOIC (D) |
| نوع التركيب | Surface Mount |
| مستوى MSL | 3 (168 hours) |
| حالة RoHS | Compliant |
تكوين أطراف OPA2277UA
| دبوس 1 | OUT A — Output of channel A |
| دبوس 2 | -IN A — Inverting input of channel A |
| دبوس 3 | +IN A — Non-inverting input of channel A |
| دبوس 4 | V- — Negative supply (or GND for single-supply operation) |
| دبوس 5 | +IN B — Non-inverting input of channel B |
| دبوس 6 | -IN B — Inverting input of channel B |
| دبوس 7 | OUT B — Output of channel B |
| دبوس 8 | V+ — Positive supply |
التطبيقات النموذجية
OPA2277UA مناسب لـ 7 التطبيقs: Precision Weighing Scale / Load-Cell Front End, Industrial 4-20 mA Current Loop Transmitter, Thermocouple / RTD Temperature Measurement, Medical Instrumentation Front End (ECG / EEG), Precision Active Filters (Sallen-Key, Multiple-Feedback), Reference-Voltage Buffer for 16/18-bit ADCs, Strain-Gauge Bridge Signal Conditioning.
Precision Weighing Scale / Load-Cell Front End
Why OPA2277UA fits: its 10 µV max Vos and ±0.1 µV/°C drift preserve the µV-level bridge outputs of a 350 Ω load cell where general-purpose op-amps (typical 1-5 mV Vos) would saturate the ADC's input range after just a few degrees of self-heating. The 140 dB CMRR additionally rejects 50/60 Hz mains pickup on long cable runs. Circuit role: two instrumentation-grade OPA2277 channels serve as the first two gain stages after the bridge, driving a 16-bit or 18-bit ADC with a 1.5 V bridge excitation; the OPA2277's ±14 V output swing on ±15 V allows direct ADC drive without an intermediate buffer. Design consideration: although 1 MHz GBW is ample for DC weighing, EMI filtering at the input is recommended to keep RF from being rectified by the bipolar input stage at high gain.
موصى به
Industrial 4-20 mA Current Loop Transmitter
Why OPA2277UA fits: a 4-20 mA loop transmitter requires a low-offset, low-drift input amplifier plus an output op-amp that drives the compliance voltage (typically 12-24 V), and the OPA2277's 800 µA quiescent current and ±18 V supply tolerance let both functions share one supply rail. Circuit role: the OPA2277's channel A buffers the sensor signal into the V-to-I conversion network, and channel B sets the loop current via a shunt reference; the wide supply range (4 V to 36 V single) handles the 24 V industrial loop directly. Performance consideration: high CMRR (>100 dB up to 1 kHz) ensures that ground-loop noise in long field wiring does not appear at the controller's input; per TI's OPAx277 datasheet, OPA2277 is recommended for IEC 61000-4-compliant industrial sensor interfaces.
موصى به
Thermocouple / RTD Temperature Measurement
Why OPA2277UA fits: thermocouple signals are sub-millivolt (Type K at 200°C is ~8 mV), making the OPA2277's 10 µV Vos roughly three orders of magnitude smaller than the signal - drift, not offset, is the dominant error source, and ±0.1 µV/°C drift preserves sub-0.1°C accuracy across industrial -40°C to +125°C ambient. Circuit role: the OPA2277's channel A provides the high-gain thermocouple preamp with cold-junction compensation summing node, and channel B buffers the reference-junction silicon diode; the rail-to-rail output within 1 V of rails makes single-supply 5 V designs feasible. Performance consideration: low bias current (typ 1 nA) of the OPA2277 minimizes self-heating errors in high-impedance thermocouple circuits.
موصى به
Medical Instrumentation Front End (ECG / EEG)
Why OPA2277UA fits: ECG and EEG signals occupy 0.5 Hz-150 Hz with amplitudes of 0.5 mV to 5 mV and are buried in 50/60 Hz mains interference; the OPA2277's 140 dB CMRR and 130 dB PSRR provide the basis for IEC 60601-1-compliant right-leg-drive and gain stages. Circuit role: the OPA2277 forms the input instrumentation preamp (channels A and B in a three-op-amp topology) where its low 1/f noise and 10 µV Vos are essential to avoid baseline wander; total input-referred noise is dominated by the OPA2277's voltage noise density of ~3.9 nV/√Hz at 1 kHz per the TI OPAx277 datasheet. Performance consideration: although CMRR is excellent, active right-leg-drive circuitry using the OPA2277 is recommended for patient-safety applications where passive ground isolation alone is insufficient.
موصى به
Precision Active Filters (Sallen-Key, Multiple-Feedback)
Why OPA2277UA fits: Sallen-Key low-pass and high-pass filters used in instrumentation demand low offset to prevent DC drift of the filter's corner frequency and to avoid saturating the next ADC stage; the OPA2277's 10 µV Vos gives a small enough offset error that 1% M-C resistors can be used without calibration. Circuit role: the OPA2277's unity-gain-stable compensation, 1 MHz GBW, and 2 V/µs slew rate make it ideal for low-frequency filter stages (sub-50 kHz) including multiple-feedback bandpass and state-variable filters; rail-to-rail output allows single-supply 5 V filter designs. Performance consideration: at gains above 10, the OPA2277's GBW starts to limit the achievable corner frequency, so designers should either limit gain-bandwidth or move to the OPA2227 (13 MHz GBW) pin-compatible family for higher-frequency filter stages.
موصى به
Reference-Voltage Buffer for 16/18-bit ADCs
Why OPA2277UA fits: precision SAR and delta-sigma ADCs (e.g., ADS1256, AD7768) draw transient currents at the reference pin during conversion, which would droop the reference voltage across any non-zero source impedance; the OPA2277's low output impedance (<0.01 Ω at DC) and 800 µA continuous output current capability isolate the reference buffer from the ADC's switching transients. Circuit role: the OPA2277 (channel A) buffers a low-drift shunt reference such as REF5025 or ADR01; channel B can be used as a second unity-gain buffer for the ADC's analog supply pin. Performance consideration: although the OPA2277 has 1 MHz GBW (limiting transient response at the ADC's sampling edge), the integrated noise of the OPA2277 in the audio band (~0.1 Hz to 100 kHz) is far below the ADC's own noise, preserving the ADC's SNR.
موصى به
Strain-Gauge Bridge Signal Conditioning
Why OPA2277UA fits: strain gauges produce sub-millivolt outputs proportional to mechanical stress, and the OPA2277's 10 µV max Vos plus ±0.1 µV/°C drift keep gain errors below 1% across the industrial -40°C to +125°C range; without this low drift, the bridge amplifier's output would shift noticeably as the equipment warms up. Circuit role: the OPA2277 forms the first gain stage (typically gain 100-500) of the bridge amplifier, with the second stage providing the offset trim and reference injection; the OPA2277's high CMRR (140 dB) rejects common-mode noise from the bridge excitation supply. Performance consideration: the OPA2277's 1 MHz GBW is more than adequate for DC- and audio-bandwidth strain measurements, but for vibration analysis above 50 kHz the OPA2227 should be considered.
موصى به
ملخص المنتجات الموصى بها
بيانات مرجعية هندسية لـ OPA2277UA — المقارنة وإرشادات التصميم ومعلومات الامتثال.
دليل الاختيار
المقارنة مع البدائل
| المعامل | هذا المنتج | OPA2227UA | OPA2277UA/2K5 | OPA2277PA |
|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | SOIC-8 (D) | SOIC-8 (D) | SOIC-8 (D) | PDIP-8 |
| Number of Channels | 2 (Dual) | 2 (Dual) | 2 (Dual) | 2 (Dual) |
| Input Offset Voltage (max) | 10 µV | 10 µV | 10 µV | 10 µV |
| Offset Drift (typ) | ±0.1 µV/°C | ±0.1 µV/°C | ±0.1 µV/°C | ±0.1 µV/°C |
| Gain-Bandwidth Product | 1 MHz | 13 MHz | 1 MHz | 1 MHz |
| Slew Rate | 2 V/µs | 5 V/µs | 2 V/µs | 2 V/µs |
| Quiescent Current (typ per channel) | 800 µA | 925 µA | 800 µA | 800 µA |
| Supply Voltage Range | ±2 V to ±18 V | ±2 V to ±18 V | ±2 V to ±18 V | ±2 V to ±18 V |
| Operating Temperature Range | -40°C to +125°C | -40°C to +125°C | -40°C to +125°C | -40°C to +125°C |
| Approx. qty-1 Unit Price | $4.62 | $4.10 | $3.20 (reel) | $6.20 |
أبرز الفروقات
- Lowest quiescent current in TI's OP-177-replacement family (مقابلOP-177 (legacy predecessor))
- Pin-compatible upgrade to OPA2227 with higher GBW when needed (مقابلOPA2227UA)
- Reel-packaged option for high-volume SMT production (مقابلOPA2277UA (tube))
- Through-hole alternative for prototyping and legacy boards (مقابلOPA2277PA (PDIP-8))
ملاحظات التصميم
Place a 0.1 µF ceramic bypass capacitor directly between each OPA2277UA supply pin (V+/V-) and ground, located within 5 mm of the IC body. For dual-supply operation with high-frequency noise on the rails, add a 10 µF tantalum or ceramic bulk capacitor in parallel. Per the TI OPAx277 datasheet, inadequate supply decoupling is the leading cause of observed oscillation in SOIC-8 precision op-amp designs - even unity-gain followers can show sustained oscillation above 1 MHz when decoupling is poor.
Route input traces as differential pairs with a ground reference on one side and a guard trace on the other to minimize leakage and pickup. Keep the input PCB traces guarded with a driven or grounded ring on the same layer, and avoid running digital or switching traces parallel to the input traces within 3 mm. Estimated: a 1 cm parallel trace at 1 cm spacing adds roughly 0.1 pF of stray capacitance, which at 1 MHz produces a phase error of <1° but at high gain (100+) creates measurable oscillation risk above 50 kHz.
Do not assume OPA2277UA's output can drive a 600 Ω load to within 1 V of the rail on ±15 V - the datasheet specifies output swing into 2 kΩ only; if your load is <2 kΩ, de-rate the swing to ±13 V or move to the OPA2156 / OPA2211 rail-to-rail output part. Note also that the OPA2277 does not have input protection diodes to the supplies; input voltages beyond the rails by more than 0.7 V can permanently damage the input stage, so external clamp diodes or input current-limiting resistors (>10 kΩ) are recommended for harsh industrial environments.
The OPA2277UA's 8-pin SOIC (D) package has a θJA of approximately 160°C/W, so at 800 µA quiescent current per channel on ±15 V supplies the self-heating is only ~24 mW (junction rise ~4°C). Estimated: assuming a maximum ambient of 85°C, the junction reaches ~89°C, well within the 125°C limit. Thermal shutdown is not required, but airflow and copper pour on the SOIC-8 lands still help stabilize Vos offset drift by limiting package temperature rise above ambient.
معلومات الامتثال
RoHS compliant and lead-free per the TI OPAx277 datasheet qualification summary. REACH SVHC statement is available on TI's compliance portal under the OPAx277 family. AEC-Q100 automotive qualification is NOT available for OPA2277UA - choose OPA2277-Q1 if automotive-grade qualification is required.
