INA105BM - Unity Gain Differential Amplifier, 1 MHz | Texas Instruments
料号： INA105BM ✓ 量产中INA105BM 概述
An instrumentation amplifier is a differential amplifier optimized for measuring small signals riding on a large common-mode voltage. This INA105 variant is the fixed unity-gain member of that family: it is used when a designer needs accurate subtraction of two input voltages without building a discrete four-resistor difference network. The INA105 family is offered in 8-pin plastic DIP, SOIC surface-mount, and TO-99 metal can packages, and the BM suffix denotes the round metal-can, wire-lead industrial-grade orderable.
Key characteristics of the INA105BM include a fixed unity differential gain of 1, a 1 MHz small-signal bandwidth as specified for this device, an integrated laser-trimmed metal film gain network, and a single-amplifier topology that needs no external gain-setting resistors. Because the gain network is on-chip, temperature drift and tolerance of the network are trimmed at the factory, which simplifies calibration and removes the resistor-matching problems that dominate discrete difference amplifiers.
Technically, the INA105BM combines a precision op-amp core with four matched, thin-film metal film resistors forming a differential-to-single-ended unity-gain network. Common-mode rejection depends directly on the matching of this on-chip network, which is why the device is laser trimmed. The single differential amplifier inside the package means the part consumes less board area than a discrete difference stage and requires only bypass capacitors on the supply pins plus output decoupling for stable operation.
Typical applications include precision bridge and strain-gauge front ends, shunt current measurement in power-conversion and motor-control circuits, low-level differential sensor conditioning, laboratory and medical instrumentation, and differential receiver stages for balanced audio and communications lines. Anywhere a clean differential signal must be converted to a single-ended signal referenced to ground, the unity-gain topology removes the need for external feedback resistors.
The key design consideration is common-mode range. A unity-gain differential amplifier can only reject common-mode voltage while both inputs stay inside the input common-mode range of the internal op amp, and the TO-99 metal can is a through-hole package intended for legacy and industrial instrumentation where lead spacing, not footprint area, dominates board layout. Keep the input pair shielded from switching nodes and route them as a tightly coupled differential pair.
This page consolidates the manufacturer product description, package and ordering details, structured specification coverage, drop-in ordering-code alternatives in the same TO-99-8 footprint, and practical design notes into a single engineering reference that goes beyond the brief distributor catalogue listing.
直接替换替代料： INA105BM ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
INA105BM-BSS3
✅ 直接替换📋 参考替代料（不在目录中）
INA105BM-BS
✅ 直接替换📋 参考替代料（不在目录中）
INA105CM
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
INA105BM 最大额定值与电气特性
| 功能 | Precision unity-gain differential amplifier |
| Differential Gain | 1 (unity gain, fixed) |
| Gain-Bandwidth Product | 1 MHz |
| Temperature Grade | Industrial grade |
| 封装 | TO-99-8 metal can, 8 leads |
| Number of Terminals | 8 |
| Terminal Form | Wire |
| Package Shape | Round, cylindrical metal can |
| 安装类型 | Through-hole |
| Internal Gain Network | On-chip laser-trimmed metal film resistor network |
| Number of Amplifier Circuits | 1 |
INA105BM round, cylindrical metal can 引脚配置指南
INA105BM（round, cylindrical metal can 封装）的引脚配置。 该模拟元件具有输入、输出和电源引脚。请参阅制造商数据手册以了解失调调零、补偿和使能引脚配置。适用于信号调理和放大器电路。
暂无详细引脚数据： INA105BM.
请参阅 数据手册 以查看完整引脚配置。
典型应用
INA105BM 适用于 6 应用s: Strain Gauge and Bridge Front End, Shunt Current Measurement in Power Conversion, Medical and Laboratory Instrumentation, Balanced Audio and Differential Receiver Stages, Industrial Sensor and Transducer Conditioning, Precision Test and Measurement Front Ends.
Strain Gauge and Bridge Front End
The INA105BM suits strain-gauge and resistive bridge front ends because its laser-trimmed on-chip metal film network delivers accurate unity gain and strong common-mode rejection without external resistor matching. A Wheatstone bridge excited by a 5 V reference produces a millivolt-level differential output while the common-mode level sits near mid-supply, which is exactly the condition the INA105 was designed to reject. The fixed gain of 1 passes the bridge differential signal unchanged to the output node, so a following amplifier stage provides the additional gain, or the excitation voltage is raised to raise sensitivity. Keep the bridge excitation routed away from the input pair, match the two input trace lengths, and use a shielded guard on the low-impedance arm. The 1 MHz bandwidth comfortably covers strain signals up to tens of kilohertz, while the metal-can package provides stable mechanical mounting for long-term calibration stability.
推荐
Shunt Current Measurement in Power Conversion
The INA105BM is well matched to high-side and low-side shunt current sensing in power conversion and motor drive systems, where the measured current appears as a small differential voltage across a sense resistor while a large switching common-mode voltage is present. Its integrated laser-trimmed gain network maintains accurate unity gain and high common-mode rejection across temperature, so the current reading does not drift as the switch node slews. Because the gain is fixed at 1, the shunt value sets the sensitivity directly, and the amplified signal feeds a comparator or ADC for over-current protection and telemetry. Place the shunt as close to the amplifier pins as possible so that parasitic inductance does not convert switching current into differential error voltage. The 1 MHz bandwidth of the INA105BM captures current ripple for control-loop feedback, while the hermetic metal can keeps the sensitive input pair shielded from radiated and conducted EMI.
推荐
Medical and Laboratory Instrumentation
Medical and laboratory instrumentation front ends often work with microvolt-level sensor outputs and require stable, drift-free behaviour over long measurement campaigns, and the INA105BM provides it through a factory laser-trimmed on-chip metal film network that eliminates the resistor-matching drift typical of discrete difference amplifiers. The unity-gain stage converts a floating sensor differential output to a ground-referenced signal that can drive a precision ADC or instrumentation stage, with common-mode rejection protecting the measurement from the large electrode-referenced potentials common in bio-signal front ends. The industrial temperature grade and hermetic metal-can construction suit equipment that must hold calibration over time. Design the input stage for the lowest possible leakage around the sensor leads, and provide a clean low-noise reference for the analogue supply so the reference noise does not dominate the measured noise floor of the unity-gain path.
推荐
Balanced Audio and Differential Receiver Stages
The INA105BM can serve as a balanced differential receiver in professional audio and communications line inputs, where the useful signal is the difference between two matched conductors and the unwanted component is the common-mode hum and noise picked up along the cable. The unity-gain architecture with an on-chip trimmed network rejects that common-mode pickup while preserving the polarity of the incoming signal, and the 1 MHz bandwidth covers the full audio band with generous margin for transient fidelity. The single amplifier inside the metal can keeps the signal path short and reduces board area compared with a discrete subtractor. For a complete line receiver, follow the INA105 with a level-adjusting amplifier and a low-pass filter, and keep the input pair away from digital clocks and power inductors. Because the device is a through-hole metal can with a large body, plan the connector and mechanical mounting positions around it at the schematic stage.
推荐
Industrial Sensor and Transducer Conditioning
The INA105BM is used in industrial transducer conditioning to convert the differential output of resistive and magnetoresistive sensors into a usable single-ended signal. Factory-trimmed gain means the stage behaves consistently across production units without per-board resistor selection or manual CMRR calibration, which shortens test time on the line. The unity gain setting keeps signal levels unmodified at the output, so downstream filtering, isolation, and conversion stages can be designed independently, and the 1 MHz bandwidth passes short-duration events such as limit-switch transitions without ringing into the measurement. In plant environments the hermetic metal-can package is a practical advantage because it is mechanically robust and screens the sensitive input pair. Use twisted or shielded differential wiring from the sensor to the board, anchor the shield at a single point, and verify that the loop common-mode voltage stays inside the input common-mode window for the supply voltage you select.
推荐
Precision Test and Measurement Front Ends
Bench and laboratory test equipment uses the INA105BM as the input stage for measuring small differential quantities such as bridge imbalance, thermocouple-parallel signals, or the output error of a reference source. The unity-gain, laser-trimmed network gives repeatable behaviour between instruments and between production lots, which matters when correlating results across a fleet of test systems. A single amplifier in a metal can also minimises the number of components that must be recalibrated in service. Because the gain is fixed, the practical use case is a subtractor that removes a large known offset or feedthrough before a precision gain stage, and the 1 MHz bandwidth allows the stage to be used with dynamic signals up to tens of kilohertz. Follow the input pair with a low-noise reference and guard the board against vibration-induced changes in the differential wiring.
推荐
推荐产品汇总
工程参考数据： INA105BM ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | INA105BM-BSS3 | INA105BM-BS | INA105CM | INA105BM (ROHS) |
|---|---|---|---|---|---|
| Package | TO-99-8 metal can | TO-99-8 metal can - same | TO-99-8 metal can - same | TO-99-8 metal can - same | TO-99-8 metal can - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Differential Gain | 1 (unity, fixed) | 1 (unity, fixed) | 1 (unity, fixed) | 1 (unity, fixed) | 1 (unity, fixed) |
| Gain-Bandwidth Product | 1 MHz | 1 MHz | 1 MHz | 1 MHz | 1 MHz |
| Internal Gain Network | On-chip laser-trimmed metal film resistors | On-chip laser-trimmed metal film resistors | On-chip laser-trimmed metal film resistors | On-chip laser-trimmed metal film resistors | On-chip laser-trimmed metal film resistors |
| Number of Terminals | 8 | 8 | 8 | 8 | 8 |
| Terminal Form | Wire (through-hole) | Wire (through-hole) | Wire (through-hole) | Wire (through-hole) | Wire (through-hole) |
| Amplifier Circuits per Package | 1 | 1 | 1 | 1 | 1 |
| Temperature Grade | Industrial grade | Industrial grade | Industrial grade | Extended temperature grade | Industrial grade |
关键差异点
- Factory-trimmed on-chip metal film gain network removes external resistor matching （对比 INA105BM-BSS3)
- Same 8-lead TO-99 metal-can footprint across orderable variants （对比 INA105BM (ROHS))
- Single amplifier in a hermetic metal can with 1 MHz bandwidth （对比 INA105CM)
- Fixed unity gain keeps the signal path minimal for subtraction-only stages （对比 INA106BM)
设计说明
Route the two inputs as a tightly coupled differential pair with identical length and geometry, terminated at the device pins, and keep the pair away from switching nodes, relay contacts, and power inductors. Because the on-chip laser-trimmed network defines common-mode rejection, any asymmetry in the two input traces, plus leakage from board contaminants or a damp environment, directly degrades the CMRR that this part is bought for. If a long cable is unavoidable, use twisted-pair wiring and terminate the shield at a single point near the amplifier to avoid creating a second ground loop.
Place the supply bypass capacitors directly at the amplifier pins with the shortest possible ground return, and add a second local capacitor if the supply wiring to the board is long. The INA105 family operates from dual supplies, so both rails must be decoupled and the total supply must stay within the range given in the manufacturer data sheet. Also keep the analogue supply reference noise low: because the gain is fixed at 1, the stage does not attenuate supply ripple at the output, so supply noise appears directly as output error.
Estimated: with a dual 15 V supply, unity gain and a 2 V output swing, the internal power dissipation is approximately (15 V - 2 V) x I_load; at 10 mA load that is about 0.13 W, and at 100 mA about 1.3 W. The hermetic TO-99 metal can with its lead frame provides a good thermal path to the board copper, so provide a generous copper area under and around the can and keep the device away from heat sources. Verify the case temperature rise in the assembled enclosure rather than relying on a free-air estimate.
The most common design errors with the INA105BM are expecting a variable gain, exceeding the input common-mode range, and substituting a surface-mount variant onto a through-hole footprint. The gain is fixed at 1 with no external resistor adjustment, so a stage that needs 10x or 100x amplification must add a separate gain stage. The common-mode input window is bounded by the supply rails with the headroom stated in the data sheet, so a bridge or shunt signal that swings beyond that window will clip. Finally, the SOIC-8 INA105KU is electrically similar but needs a transition adapter or board redesign for a through-hole metal-can design.
合规信息
The INA105 family industrial-grade orderables include both standard and RoHS-marked suffixes; confirm the lead-free status for the specific orderable on the manufacturer product page. AEC-Q100 automotive qualification does not apply to this instrumentation-amplifier family.
