INA129U/2K5 - Precision Low Power INA, SOIC-8 | Texas Instruments
MPN: INA129U/2K5 ✓ Hoạt độngINA129U/2K5 Tóm tắt
An instrumentation amplifier is a precision differential amplifier with very high input impedance on both inputs, a defined and stable gain set by one external resistor, and exceptionally high common-mode rejection. The INA belongs to the family of analog front-end ICs that sit between a sensor (bridge, thermocouple, biopotential electrode) and an ADC. The category hierarchy is: instrumentation amplifier -> differential amplifier -> operational amplifier -> analog IC -> semiconductor. The three-op-amp topology isolates the input signal from the gain-setting resistor network, allowing tiny differential signals (often microvolts) to be amplified cleanly in noisy industrial environments.
Key features of the INA129U/2K5 include wideband operation up to 1.3 MHz (G = 1) with 200 kHz bandwidth even at G = 100, a 4 V/µs slew rate, ±2.25 V to ±18 V dual-supply operation (±2.25 V minimum; typically ±15 V in transducer systems), input protection to ±40 V, and a quiescent current of only 700 µA typical. The exposed SO-8 package simplifies reflow assembly on standard 8-pin SOIC land patterns identical to the INA128, AD620, and other pin-compatible INAs.
The current-feedback input stage keeps bandwidth flat across the full gain range, an advantage over voltage-feedback INAs that lose bandwidth at high gain. The INA129's gain equation G = 1 + 49.4kΩ/RG matches the AD620, allowing direct drop-in migration from legacy designs. The combination of low noise, low drift, and high CMRR makes the INA129U/2K5 well-suited for strain-gauge bridges, weigh scales, thermocouple amplifiers, medical instrumentation (ECG/EEG front-ends), and industrial process-control analog inputs.
Typical applications include weigh scales and load-cell signal conditioning, ECG and biomedical front-ends, thermocouple and RTD pre-amplification, and industrial 4-20 mA loop readouts. Place the gain-setting resistor close to pins 1 and 8, and use 0.1 µF ceramic bypass capacitors on both supply pins to preserve the 120 dB CMRR across frequency. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Bộ thay thế dễ dàng lắp đặt cho INA129U/2K5 — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
Các biến thể trong loạt này
Các mẫu cùng loạt có thể lắp đặt dễ dàng tương thích với INA129U/2K5 (cùng hình factor và footprint) — khác nhau ở Product Type, Package, Gain Range, Mounting Type, Architecture.
INA128U/2K5
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
INA128UA/2K5
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
INA121UAG4
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
AD620ANZ
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →INA333AIDR
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
INA118PB
✅ Drop-In ⚠️ Thông số chưa được xác minhLiên hệ để biết giá
Xem tài liệu →INA129U/2K5 Tỷ lệ tối đa & tính chất điện
| Manufacturer | Texas Instruments |
| Product Type | Instrumentation Amplifier (INA) |
| Series | INA12x (INA128 / INA129) |
| Number of Channels | 1 |
| Cấu trúc | 3-Op-Amp, current-feedback input |
| Hộp / Vỏ | 8-pin SOIC (SO-8) |
| Kiểu lắp đặt | Surface Mount |
| Supply Voltage (Dual) | ±2.25 V to ±18 V |
| Điện áp yên tĩnh | 700 µA typical |
| Input Offset Voltage (max) | 50 µV |
| Offset Drift (max) | 0.5 µV/°C |
| Input Bias Current (max) | 5 nA |
| CMRR (min) | 120 dB (at G = 100) |
| Bandwidth (G = 1) | 1.3 MHz |
| Bandwidth (G = 100) | 200 kHz |
| Slew Rate | 4 V/µs |
| Gain Range | 1 V/V to 10,000 V/V |
| Gain Equation | G = 1 + 49.4kΩ / RG (AD620-compatible) |
| Input Protection | ±40 V |
| Nhiệt độ hoạt động | -40 °C to +85 °C |
| Reel Quantity | 2,500 (per /2K5 suffix) |
| RoHS | Compliant |
Cấu hình chân INA129U/2K5
| Chân 1 | RG — Gain-setting resistor pin (connect external resistor to pin 8) |
| Chân 2 | -IN — Inverting input |
| Chân 3 | +IN — Non-inverting input |
| Chân 4 | V- — Negative supply voltage |
| Chân 5 | REF — Output reference (level-shift output; normally tied to GND for dual supply) |
| Chân 6 | OUTPUT — Amplifier output |
| Chân 7 | V+ — Positive supply voltage |
| Chân 8 | RG — Gain-setting resistor pin (connect external resistor to pin 1) |
Ứng dụng tiêu biểu
INA129U/2K5 phù hợp cho 6 Áp dụngs: Weigh Scale / Load Cell Signal Conditioning, ECG and Biomedical Front-End, Thermocouple and RTD Temperature Amplifier, Industrial 4-20 mA Loop Readout, Strain-Gauge Bridge Amplifier, Audio Precision Preamplifier.
Weigh Scale / Load Cell Signal Conditioning
The INA129U/2K5 is the canonical load-cell amplifier for industrial weigh scales. Its 120 dB minimum CMRR at G=100 rejects 50/60 Hz mains pickup that couples into long load-cell cables, while the 50 µV maximum offset and 0.5 µV/°C maximum drift maintain calibration accuracy across the -40 °C to +85 °C industrial range. The current-feedback input stage keeps bandwidth flat (~200 kHz) even at G=100, allowing fast settling for batch-weighing applications. Place the gain resistor close to pins 1 and 8 and add 0.1 µF ceramic bypass on both supply rails to preserve the 120 dB CMRR figure. The SOIC-8 footprint is pin-compatible with AD620, enabling direct migration.
Được đề xuất
ECG and Biomedical Front-End
The INA129U/2K5 is widely used as the first gain stage in ECG, EEG, and EMG front-ends. Its 5 nA maximum input bias current is well below typical skin-electrode impedance levels, preventing polarization of Ag/AgCl electrodes. The 120 dB minimum CMRR rejects common-mode mains interference when set to G = 10 with right-leg-drive feedback, while the 50 µV maximum offset contributes negligible baseline wander. The 1.3 MHz bandwidth captures high-frequency QRS complexes without distortion. Designers should add ESD protection (TVS arrays) and AC coupling at the inputs per AAMI EC11/IEC 60601-1 safety standards. The SOIC-8 footprint supports compact wearable designs.
Được đề xuất
Thermocouple and RTD Temperature Amplifier
The INA129U/2K5 amplifies the microvolt-level outputs of K-type, J-type, and S-type thermocouples with 50 µV offset accuracy that adds less than 1 °C error to cold-junction-compensated readings. The high CMRR rejects 50/60 Hz thermocouple-loop pickup in industrial furnaces. For RTD-based temperature sensing, the INA129's 5 nA bias current minimizes self-heating errors on PT100/PT1000 elements. The ±2.25 V to ±18 V supply range allows operation from standard ±5 V or ±15 V industrial rails. Use the REF pin (pin 5) to level-shift the output for single-supply ADC interfaces; the gain equation G = 1 + 49.4kΩ/RG simplifies resistor selection for the 1 mV/°C K-type output range.
Được đề xuất
Industrial 4-20 mA Loop Readout
The INA129U/2K5 reads the differential voltage across a current-sense resistor in 4-20 mA HART-protocol loops. Its ±40 V input protection survives field wiring faults and accidental mains contact, critical for IEC 61000-4 compatibility in process-control installations. The 120 dB CMRR rejects ground-loop noise between field transmitters and the control cabinet, while the 1.3 MHz bandwidth supports HART 1200 bps FSK modulation pass-through without attenuation. The SOIC-8 small footprint enables channel-density multi-rail acquisition cards. Power the INA129 from the same ±15 V supply that powers downstream ADCs, simplifying the BOM.
Được đề xuất
Strain-Gauge Bridge Amplifier
The INA129U/2K5 is ideal for amplifying full-bridge and half-bridge strain-gauge transducers in structural-health monitoring and pressure-sensor applications. The 120 dB CMRR ensures bridge common-mode voltage (typically 2.5 V or 5 V) is rejected to better than 1 µV, while the 50 µV offset does not compromise the millivolt-level strain signals. The 4 V/µs slew rate preserves dynamic response for vibration and impact testing. The SOIC-8 footprint and external gain resistor allow precise gain calibration per transducer sensitivity (typically 1-4 mV/V). Place a 100 nF ceramic bypass on each supply pin and keep the gain resistor within 5 mm of pins 1 and 8 to maintain CMRR.
Được đề xuất
Audio Precision Preamplifier
The INA129U/2K5 functions as a precision microphone preamp and line-level instrumentation preamp in professional audio equipment. The 1.3 MHz bandwidth and 4 V/µs slew rate support full 20 Hz-20 kHz audio bandwidth with low distortion. The 50 µV offset is inaudible in typical microphone gain (G = 100), and the 120 dB CMRR rejects ground-loop hum in balanced audio cable runs. The ±18 V maximum supply accommodates ±15 V professional audio rails. Use the REF pin to bias the output to mid-rail for single-supply ADC interfacing in digital mixers. Designers should add RF input filtering and ESD protection per IEC 61000-4-2 for stage-grade equipment.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho INA129U/2K5 — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | INA128U/2K5 | INA128UA/2K5 | AD620ANZ | INA333AIDR |
|---|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Analog Devices | Texas Instruments |
| Package | SOIC-8 (narrow) | SOIC-8 (narrow) | SOIC-8 (Wide) | SOIC-8 (narrow) | MSOP-8 |
| Topology | 3-Op-Amp, current-feedback | 3-Op-Amp, current-feedback | 3-Op-Amp, current-feedback | 3-Op-Amp, current-feedback | 3-Op-Amp, zero-drift chopper |
| Input Offset Voltage (max) | 50 µV | 50 µV | 50 µV | 50 µV | 25 µV (typ) |
| CMRR (min) | 120 dB (G=100) | 120 dB (G=100) | 120 dB (G=100) | 100 dB (G=1-1000) | 100 dB |
| Bandwidth (G=100) | 200 kHz | 200 kHz | 200 kHz | 120 kHz | 3.5 kHz |
| Slew Rate | 4 V/µs | 4 V/µs | 4 V/µs | 1.2 V/µs | 0.16 V/µs |
| Supply Voltage (Dual) | ±2.25 V to ±18 V | ±2.25 V to ±18 V | ±2.25 V to ±18 V | ±2.3 V to ±18 V | +1.8 V to +5.5 V (single supply) |
| Gain Equation | G = 1 + 49.4kΩ/RG (AD620-compatible) | G = 1 + 50kΩ/RG (industry std) | G = 1 + 50kΩ/RG (industry std) | G = 1 + 49.4kΩ/RG (same) | G = 1 + 100kΩ/RG |
Bảo phân biệt quan trọng
- AD620-compatible gain equation for direct legacy migration (vsINA128U/2K5)
- Higher CMRR than AD620 for industrial noise environments (vsAD620ANZ)
- Current-feedback input stage maintains bandwidth at high gain (vsINA333AIDR (zero-drift))
Ghi chú thiết kế
Place the gain-setting resistor RG within 5 mm of pins 1 and 8 to minimize parasitic capacitance that degrades CMRR at high frequencies. Use 0.1 µF ceramic bypass capacitors on both V+ (pin 7) and V- (pin 4), positioned within 3 mm of the supply pins. Route input traces as a matched differential pair with guard traces tied to REF potential (pin 5) to reduce common-mode pickup on long sensor cables.
The REF pin (pin 5) is the output common-mode reference and must be driven from a low-impedance source. For dual-supply operation, tie REF directly to ground. For single-supply operation, drive REF from a buffered mid-rail (e.g., a resistor divider with 10 µF bypass) to level-shift the output swing above ground. Driving REF with high impedance introduces common-mode noise and degrades the 120 dB CMRR figure.
Do not exceed the ±40 V input protection rating; in industrial installations, add external TVS diodes or spark gaps for IEC 61000-4-5 surge compliance. Do not connect input signals before power is applied - the input protection clamps can forward-bias and damage downstream circuitry. Use the correct gain-resistor package (typically 0805 or 0603) with 0.1% tolerance for gain accuracy; 1% resistors introduce 1% gain error that propagates to system calibration.
Thông tin tuân thủ
RoHS compliant per TI product page. Not AEC-Q100 qualified; for automotive applications consider INA129-Q1. Lead-free SOIC-8 package with NiPdAu lead finish.
