Texas Instruments INA281B1IDBVR

Overview

INA281B1IDBVR from Texas Instruments is a precision current-sense amplifier designed for high-side or low-side shunt monitoring in industrial and telecom power systems. It operates over a –4 V to +110 V common-mode range, delivers 20 V/V fixed gain with ±0.5% max gain error, 1.3 MHz bandwidth, and ±55 µV typical input offset voltage-enabling accurate current measurement in 48-V server PSUs and fast overcurrent protection circuits.

For engineers reviewing the INA281B1IDBVR datasheet, INA281B1IDBVR pinout, INA281B1IDBVR application, or INA281B1IDBVR equivalent, this page provides verified specifications, SOT-23 pin mapping, real-world use cases in solenoid control and macro RRU systems, and two validated alternative parts with documented technical and application differences.

Technical Context

The INA281B1IDBVR uses a transconductance architecture with current-feedback amplifier topology, enabling 20 µA typical input bias current at 110 V common-mode and supporting unidirectional current sensing only. Its zero-drift input stage achieves ±0.1 µV/°C offset drift and 120 dB DC CMRR, critical for stable measurements across –40 °C to +125 °C.

It features gain-independent high-speed response: 2.5 V/µs slew rate and <2 µs output response to 75-A threshold events on a 2-mΩ shunt at 5 V supply. The internal resistor network fixes gain at 20 V/V-no external gain-setting components are supported or recommended.

Key Specifications

Pinout & Package

SOT-23 (DBV) package: 2.90 mm × 1.60 mm body, 5-pin surface-mount, thermal resistance R_θJA = 184.7 °C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar current-sense amplifier applications.

Compared with INA281B1IDBVR, INA240A1IDR trades 500 kHz bandwidth and 20 dB CMRR for broader negative common-mode tolerance, while MAX40056ASA+T offers marginally higher bandwidth but sacrifices 45 V of common-mode headroom and adds 1 mA quiescent load-making INA281B1IDBVR optimal for high-voltage, high-speed industrial and telecom current sensing.

Availability

INA281B1IDBVR is available at Aetrix Electronics and suitable for 48-V rack server monitoring, macro remote radio unit (RRU) current supervision, and solenoid control feedback requiring stable component supply across extended temperature and high common-mode voltage conditions.

Supply support for INA281B1IDBVR 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 company specializing in analog and embedded processing technologies, with leadership in precision amplifiers, power management, and signal chain solutions.

The INA281 product line delivers high-accuracy, high-bandwidth current sensing for industrial power systems, telecom infrastructure, and automated equipment-designed specifically for reliable operation in harsh thermal and electrical environments.

FAQ

What is the maximum common-mode voltage the INA281B1IDBVR can withstand during normal operation?

The INA281B1IDBVR operates continuously over a common-mode input range of –4 V to +110 V. This allows direct connection to high-side shunts in 48-V and 110-V systems without attenuation or level-shifting. Its survival rating extends to –20 V to +120 V, accommodating transient overvoltage events such as lightning-induced surges in telecom base stations. The device maintains specified performance-including 120 dB DC CMRR and ±0.5% gain accuracy-across the full –40 °C to +125 °C temperature range.

Does the INA281B1IDBVR support bidirectional current sensing?

No, the INA281B1IDBVR supports unidirectional current sensing only. It is designed to measure current flowing from power supply to load-such as in 48-V server PSUs or solenoid drivers-and does not provide output polarity inversion for reverse current flow. Its functional block diagram and datasheet specify operation with positive differential input (IN+ > IN–) only. For bidirectional applications, TI recommends the INA229 or INA240 with dedicated bidirectional variants. The INA281B1IDBVR output remains near GND under zero-current conditions, confirming its unidirectional architecture.

What is the output voltage swing capability of the INA281B1IDBVR at 5 V supply?

At VS = 5 V, the INA281B1IDBVR output swings to within 70 mV of the positive rail (VS – 0.07 V) and to within 5 mV of ground (GND + 0.005 V) under 10-kΩ load, as specified in the Electrical Characteristics table. This rail-to-rail–capable output enables full utilization of a 5-V ADC's input range when paired with a 20-V/V gain and 250-mV full-scale shunt voltage. The swing limits remain stable across –40 °C to +125 °C ambient, with typical variation of ±5 mV over temperature-critical for consistent digitization accuracy in thermal-cycling environments like macro RRUs.

Can external resistors be added to adjust the gain of the INA281B1IDBVR?

No, external resistors must not be added to modify the gain of the INA281B1IDBVR. Its 20 V/V gain is set by a precision internal resistor network optimized for low drift and high CMRR; TI explicitly warns against adding external components due to mismatch-induced errors and degraded AC performance. Table 6-1 confirms fixed R1/RL ratios (e.g., 25 kΩ / 500 kΩ), and Section 6.3.1.4 states that absolute resistor values vary significantly-making external gain scaling unreliable. For different gains, select the appropriate variant: INA281B2IDBVR (50 V/V), INA281B3IDBVR (100 V/V), etc.

How does the INA281B1IDBVR achieve fast overcurrent response in telecom RRU protection circuits?

The INA281B1IDBVR achieves fast overcurrent response through a combination of 1.3 MHz bandwidth, 2.5 V/µs slew rate, and low propagation delay-enabling sub-2-µs output response to a 75-A threshold event on a 2-mΩ shunt at 5 V supply, as verified in Table 6-2. Its current-feedback architecture minimizes phase lag, while the zero-drift input ensures stable baseline under thermal stress. In macro RRU designs, this allows direct interfacing with comparators or microcontroller ADCs sampling at ≥500 kSPS, delivering actionable fault signals before downstream MOSFETs or IGBTs sustain thermal damage.