INA121U - Low-Power FET Instrumentation Amplifier | Texas Instruments
部品番号: INA121U ✗ 生産終了| 数量 | 単価 | 小計 |
|---|---|---|
| 1 | $7.6879 | $7.69 |
| 10 | $7.6879 | $76.88 |
| 100 | $7.6879 | $768.79 |
| 500 | $7.6879 | $3,843.95 |
| 1,000 | $7.6879 | $7,687.90 |
INA121U 概要
An instrumentation amplifier is a specialized analog amplifier that provides differential input, high input impedance, accurate differential gain, and strong common-mode rejection. The INA121 belongs to the broader hierarchy of operational amplifiers, analog amplifiers, signal-conditioning ICs, and semiconductors. Its three-op-amp design makes it suitable for bridge sensors, current measurements, biomedical instrumentation, and industrial sensor interfaces where the common-mode voltage may be much larger than the wanted signal.
Verified features include low input offset voltage of ±200 µV, low input offset drift of ±2 µV/°C, high common-mode rejection of 106 dB, and low nonlinear-ty error of 0.001%. The input-noise specification is listed as 100 nV/√Hz in the verified search data. These characteristics support precision measurement by reducing offset error, drift, common-mode interference, and amplitude distortion. The device is identified as a one-amplifier, 8-SOIC instrumentation amplifier by DigiKey.
The INA121’s low-power design is useful when system power is constrained or when added analog circuitry would otherwise increase overall power consumption. The wide supply range supports both low-voltage portable systems and higher-voltage industrial interfaces, although the actual signal and output headroom must remain within the device ratings. The ±450 µA quiescent-current value is especially relevant to battery-powered and distributed sensor systems.
Typical applications include strain-gauge and load-cell bridges, thermocouple and temperature-sensor front ends, low-current measurement, biomedical instrumentation, industrial process monitoring, and general differential signal conditioning. The design should provide suitable input filtering, power bypassing, gain-setting resistors, and output-voltage headroom. Pin assignment, gain calculation, and common-mode limits should be confirmed from the manufacturer datasheet before layout release.
This product data consolidates the verified manufacturer description, distributor package identification, feature snippets, and sourcing links for INA121U. Pricing tiers below use the distributor value explicitly available as of 2026-10-22; the LCSC listing is for the distinct INA121U/2K5 ordering variant and is not substituted for INA121U.
ドロップイン代替品: INA121U — 同一パッケージでピン互換。PCBの作り直しが必要な異なるパッケージの部品は除外されています。
このシリーズのバリエーション
同一シリーズでドロップイン互換のモデル: INA121U （同一形状・フットプリント） — 相違点: Input Bias Current, Input Offset Drift, Input Offset Voltage, Number of Channels, Package.
クイック比較ツール — 並列比較する代替部品を選択:
INA121UA
✅ ドロップイン✓ 在庫あり
$4.95 / 個
データシートを見る →INA121UG4
✅ ドロップイン📋 参考代替品（カタログ未掲載）
INA121U/2K5
✅ ドロップイン📋 参考代替品（カタログ未掲載）
INA126U/2K5
✅ ドロップイン📋 参考代替品（カタログ未掲載）
INA128U
✅ ドロップイン📋 参考代替品（カタログ未掲載）
INA121U 最大定格＆電気的特性
| Product Type | FET-input, low-power instrumentation amplifier |
| Number of Channels | 1 circuit |
| Input Bias Current | ±4 pA |
| 静止電流 | ±450 µA |
| Input Offset Voltage | ±200 µV |
| Input Offset Drift | ±2 µV/°C |
| Input Noise | 100 nV/√Hz |
| Common-Mode Rejection | 106 dB |
| Supply Range | ±2.25 V to ±18 V |
| Bandwidth | 600 kHz |
| Nonlinearity Error | 0.001% |
| 動作温度 | -40 °C to +85 °C |
| パッケージ | 8-pin SOIC |
| 実装タイプ | Surface mount |
| Application Category | Instrumentation amplifier |
| Architecture | Three-op-amp instrumentation-amplifier design |
| Input Type | Differential input |
| Manufacturer | Texas Instruments |
| RoHS ステータス | unknown |
| REACH Status | unknown |
INA121U 8-pin soic ピン配置ガイド
INA121U (8-pin soic パッケージ) のピン配置。 このアナログコンポーネントは、入力、出力、および電源ピンを備えています。オフセットナル、補償、イネーブルピンの設定については、メーカーのデータシートを参照してください。信号調整やアンプ回路に最適です。
詳細なピン配置データはありません: INA121U.
詳細は データシート をご参照ください。
主な用途
INA121U の用途: 6 件s: Load-Cell and Strain-Gauge Amplification, Temperature and Thermocouple Sensing, Low-Current Sensor Interfacing, Biomedical and Patient-Instrumentation Front Ends, Industrial Process Measurement, Battery-Powered Sensor Node.
Load-Cell and Strain-Gauge Amplification
The INA121U fits load-cell and strain-gauge front ends because its differential input architecture amplifies the small bridge imbalance while rejecting common-mode voltage. The verified 106 dB common-mode rejection helps reduce errors when the bridge excitation and signal node are affected by supply noise or ground disturbance. Its ±4 pA input bias current is valuable for high-impedance bridge networks, while the ±450 µA quiescent current supports power-constrained instrumentation. Set the gain and output range against the bridge excitation, sensor sensitivity, and the INA121U common-mode and output-swing limits. Place input filtering and gain-setting components close to the amplifier to reduce leakage, thermal drift, and pickup.
おすすめ
Temperature and Thermocouple Sensing
INA121U can condition low-level differential signals from temperature sensors when the source impedance and common-mode conditions are compatible. Its low input bias current reduces errors associated with leakage through high-value sensor or bias resistors, and its low offset drift of ±2 µV/°C supports temperature-sensitive measurements. The ±2.25 V to ±18 V supply range also provides flexibility for industrial and low-voltage sensor systems. The key trade-off is that thermocouple signals are small and may require gain, filtering, and careful cold-junction compensation. Confirm the input common-mode range, output swing, and noise performance in the manufacturer datasheet before selecting the gain and supply rails.
おすすめ
Low-Current Sensor Interfacing
INA121U is appropriate for low-current and shunt-based measurements when the voltage drop is small relative to the amplifier’s input and output capabilities. The ±4 pA input bias current is particularly useful with high-impedance sensing paths, where bias leakage can become comparable to the measured current. The 600 kHz bandwidth provides useful signal bandwidth for many industrial and diagnostic waveforms, although the selected gain must preserve adequate bandwidth and stability. Use low-leakage PCB materials, guard structures, and clean grounding around the input nodes. Verify whether the shunt signal is referenced to ground or rides on a common-mode voltage, then size the gain so the output remains within the amplifier’s swing range.
おすすめ
Biomedical and Patient-Instrumentation Front Ends
The INA121U can serve as an analog front end for low-level biomedical signals when the application satisfies its input, supply, and safety requirements. Its low bias current supports measurements from high-impedance sources, while the instrumentation-amplifier topology helps reject common-mode interference coupled into the sensor environment. The low quiescent current is beneficial for portable instruments, although battery life, leakage, noise, and patient-safety requirements dominate the final design. Do not infer medical certification from the component description. Validate isolation, protection, leakage current, electrode compatibility, and regulatory requirements with the complete system design and applicable medical standards.
おすすめ
Industrial Process Measurement
INA121U is useful in industrial process-measurement systems where a small sensor signal must be measured in the presence of a larger process common-mode voltage. Its 106 dB common-mode rejection improves signal integrity in systems with long sensor wiring or shared industrial grounds. The ±2.25 V to ±18 V supply range supports different rail arrangements, while the 8-pin SOIC package is practical for compact analog boards. The design must include input protection, filtering, surge handling, grounding, and calibration appropriate to the sensor. Because the verified data does not provide transient immunity or industrial certification, these requirements must be verified separately rather than inferred from the package or temperature rating.
おすすめ
Battery-Powered Sensor Node
INA121U fits battery-powered sensor nodes that must amplify a weak differential signal without adding excessive standby power. The verified quiescent current of ±450 µA is a useful design input when estimating battery drain, although total consumption also includes gain-setting resistors, filtering, output loading, and any associated ADC. The low bias current can improve measurement accuracy with high-impedance sensors and reduce leakage-related drift. Use low-leakage PCB construction and disable or power-gate surrounding analog sections when the node is inactive. The available supply range must be reconciled with the battery voltage, and the final design should account for the amplifier’s noise, offset, common-mode limits, and output swing rather than power alone.
おすすめ
おすすめ製品の概要
エンジニアリング参考データ: INA121U — 比較、設計ガイダンス、コンプライアンス情報。
選定ガイド
代替品との比較
| パラメータ | この製品 | INA121UA | INA121UG4 | INA121U/2K5 | INA126U/2K5 | INA128U |
|---|---|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Product Type | FET-input, low-power instrumentation amplifier | INA121 instrumentation amplifier | Instrumentation amplifier | Instrumentation amplifier | Instrumentation amplifier | Instrumentation amplifier |
主な差別化要因
- Low-power instrumentation-amplifier positioning （vs INA126U/2K5)
- Very low input bias current （vs INA128U)
- Specified bandwidth and common-mode rejection （vs INA121UG4)
設計ノート
Keep the two differential input paths short, symmetric, and away from switching nodes and high-current traces. Place gain-setting resistors and input-filter components close to the INA121U pins, and use a quiet ground return for the analog section. Because the device is specified at ±4 pA input bias current, contaminated PCB surfaces, long leakage paths, and protection leakage can materially affect high-impedance sensor measurements. The verified data does not provide the complete pinout, so the physical layout must be checked against the manufacturer datasheet and package drawing.
Design the supply rails so the input common-mode voltage and output signal remain within the INA121U operating limits. The verified range is ±2.25 V to ±18 V, but supply compatibility alone does not guarantee output regulation. Place bypass capacitors near the supply pins and provide stable references for any external gain-setting network. For low-power systems, estimate the INA121U quiescent contribution using the verified ±450 µA value and add the actual sensor, resistor, ADC, and protection-network consumption rather than relying on the amplifier value alone.
Match input filtering to the intended sensor bandwidth. The verified bandwidth is 600 kHz, so excessive bandwidth can admit noise, while excessive filtering can slow valid signal measurements. For bridge, thermocouple, or shunt inputs, check source impedance and differential input capacitance against the manufacturer’s stability guidance. Use common-mode rejection as a system advantage only after accounting for cable pickup, ground differences, surge pulses, and resistor tolerances; the 106 dB figure is a device specification, not immunity to every external interference source.
コンプライアンス情報
The supplied verified data does not explicitly state RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals status for INA121U. The verified industrial temperature range is -40 °C to +85 °C, but that is not evidence of automotive qualification.