ACS781KLRTR-150B-T

Allegro MicroSystems ACS781KLRTR-150B-T Overview

The Allegro MicroSystems ACS781KLRTR-150B-T is an automotive-grade, Hall-effect linear current sensor designed for both AC and DC measurements up to ±150 A. Part of the ACS781 family, this 3.3 V “K” variant integrates a low-resistance primary conductor and delivers an analog, ratiometric output proportional to the sensed current. The “B” option denotes bidirectional measurement with the output centered around VCC/2, enabling precise monitoring of positive and negative currents. Housed in the compact LR PSOF-7 (CB-PSSOIC-7) package and supplied in tape-and-reel for high-volume assembly, this device is a strong fit for high-current automotive and industrial systems that require galvanic isolation and reliable, repeatable performance.

Engineers, buyers, and sourcing managers trust the ACS781KLRTR-150B-T for applications ranging from traction inverter phase sensing to DC/DC power-stage monitoring. With AEC‑Q100 qualification at the family level and RoHS compliance, it aligns with modern automotive quality and environmental standards. When you need a compact, surface-mount current sensor with bidirectional measurement at a 3.3 V supply, the Allegro MicroSystems ACS781KLRTR-150B-T is a practical, design-ready choice.

Key Benefits and Features

• Hall-effect linear current sensor with integrated primary conductor
• Bidirectional measurement up to ±150 A (ACS781KLRTR-150B-T)
• 3.3 V supply operation (“K” variant)
• Analog output, ratiometric to VCC (centered at VCC/2 for bidirectional sensing)
• Measures AC and DC currents with galvanic isolation via the Hall structure
• Automotive-grade device (AEC‑Q100, family/ordering option dependent)
• Compact LR PSOF-7 (CB-PSSOIC-7) package; tape-and-reel packaging for SMT lines

Where the ACS781KLRTR-150B-T Fits Best

• Automotive motor/inverter control and phase current monitoring
• Battery management and pack current measurement
• Overcurrent and short-circuit detection in power electronics
• DC/DC converters, on-board chargers, and general power supplies
• Industrial drives, motion control, and high-current loads

How the Allegro MicroSystems ACS781KLRTR-150B-T Works

The ACS781KLRTR-150B-T uses a Hall-effect transducer to sense the magnetic field generated by current flowing through its integrated primary conductor. Because the conductor is built into the package, there is no need for external shunts or magnetic cores. The Hall element measures the magnetic flux, and internal signal conditioning produces an analog output proportional to current.

For the “B” bidirectional option, the transfer function is centered around VCC/2. Positive current causes the output voltage to move above VCC/2, while negative current drives it below VCC/2. The “K” supply code signifies operation from a 3.3 V rail, making this part particularly convenient for modern microcontroller- and SoC-based systems that standardize on 3.3 V analog domains. Because the output is ratiometric, the device’s output scales with the supply voltage, simplifying ratiometric ADC schemes and system-level calibration.

Galvanic isolation between the measurement path and the low-voltage signal interface is achieved through the Hall-effect sensing architecture. This helps protect sensitive control electronics from high voltages present in power stages while enabling accurate current feedback.

Specifications at a Glance

• Manufacturer/Brand: Allegro MicroSystems
• Series: ACS781
• MPN: ACS781KLRTR-150B-T
• Category: Current Sensors
• Type: Hall-effect linear current sensor
• Sensing Range: ±150 A (bidirectional)
• Supply Voltage: 3.3 V nominal (“K” variant)
• Output Type: Analog, ratiometric to VCC
• Measurement: AC and DC
• Automotive Qualification: AEC‑Q100 (family dependent)
• Package: LR PSOF-7 (CB-PSSOIC-7)
• Mounting: Surface Mount
• Pin Count: 7
• Packaging: Tape & Reel (TR)

Electrical Characteristics

• Input supply (VCC): 3.3 V nominal (“K” variant)
• Output behavior: Ratiometric analog; centered at VCC/2 for bidirectional (“B”) option
• Sensitivity/transfer function slope: Not specified in datasheet
• Accuracy/total error over temperature: Not specified in datasheet
• Bandwidth/response time: Not specified in datasheet
• Noise performance: Not specified in datasheet

Mechanical and Environmental

• Package/case: LR PSOF-7 (CB-PSSOIC-7), surface-mount
• Operating temperature range: -40°C to 125°C
• Isolation method: Galvanic isolation via integrated Hall-effect structure
• Isolation rating: Not specified in datasheet

Design and Integration Guidance

Power and Signal Interface

• Supply the ACS781KLRTR-150B-T from a clean 3.3 V rail. Because the output is ratiometric to supply voltage, designs that use the same VCC reference for the ADC can benefit from reduced relative measurement error due to supply variation.
• Include adequate local decoupling near the VCC pin. While the specific capacitor values and layout requirements are not provided here, following standard high-current analog layout practices (short, wide traces; solid ground reference) is recommended.

Output Interpretation and Calibration

• For the “B” bidirectional device, treat VCC/2 as zero current and map deviations above/below this midpoint to positive/negative current, respectively.
• Implement a system-level zero-current calibration at power-up to null offsets introduced by component tolerances and PCB/system magnetics.
• If your application requires tight absolute accuracy, perform end-of-line calibration across relevant temperature points. Specific accuracy figures are not provided here and should be confirmed from the latest Allegro datasheet.

PCB Layout and Current Path

• Route the high-current path consistent with the package’s integrated conductor orientation. Ensure adequate copper and thermal relief around the sensor’s primary conductor footprints to handle the intended current range.
• Maintain separation between noisy switching nodes and the analog output trace. Differential measurement or filtering at the ADC input may further improve robustness.

Isolation and Safety

• The device provides galvanic isolation via Hall-effect sensing. Confirm isolation rating and creepage/clearance for your end equipment per regulatory requirements. Isolation rating is not specified in the datasheet excerpt provided here.
• Observe applicable safety standards for high-voltage automotive and industrial systems.

EMC and Filtering

• Add modest analog filtering (e.g., RC network) if your system experiences switching noise or if you need to tailor bandwidth. Bandwidth and recommended filter values are not specified in the datasheet excerpt provided here; consult the full datasheet and evaluate empirically.

Applications and Use Cases

• Traction inverter phase current sensing in xEV powertrains
• 48 V mild hybrid systems—starter generators, DC/DC converters, and battery rails
• On-board chargers and power distribution units where galvanic isolation is desirable
• Industrial motor drives and servo loops needing linear, bidirectional feedback
• Overcurrent/short-circuit detection in high-current DC buses
• Power supplies and converters that benefit from ratiometric analog telemetry

These scenarios benefit from the ACS781KLRTR-150B-T’s integrated conductor, compact footprint, and 3.3 V-logic-friendly analog output, reducing BOM complexity compared with discrete shunt-and-amplifier solutions.

Ordering, Part Number Decoding, and Packaging

• ACS781: Allegro MicroSystems Hall-effect linear current sensor family
• K: 3.3 V supply variant
• LR: LR PSOF-7 package style
• TR: Tape-and-reel packaging for automated assembly
• 150: ±150 A sensing range (family coding)
• B: Bidirectional output centered at VCC/2
• T: Specific ordering/packaging code as published by the manufacturer

Shipped in tape-and-reel for high-volume SMT processes, the ACS781KLRTR-150B-T simplifies procurement and assembly. For program managers, ensure that the “K” and “B” codes match your electrical design: 3.3 V supply compatibility and bidirectional measurement are not drop-in compatible with 5 V or unidirectional variants.

Lifecycle, Compliance, and Quality

• Lifecycle status: Active
• Environmental compliance: RoHS Compliant (lead-free)
• Automotive quality: AEC‑Q100 (family dependent; verify for your exact ordering code)

These attributes make the Allegro MicroSystems ACS781KLRTR-150B-T suitable for long-running automotive and industrial platforms that require conformity with global environmental and quality frameworks. Always confirm the specific AEC‑Q100 grade and documentation for your selected ordering option.

Approved Alternates and Cross-Selection Guidance

When second-sourcing or evaluating alternatives, match electrical behavior, package, and calibration carefully. The following are manufacturer-provided family alternatives; evaluate the datasheet details before substitution:

• ACS781KLRTR-150U-T: Unidirectional 150 A variant in the same family/package. Output transfer function differs (offset not centered at VCC/2), so firmware and calibration may require changes.
• ACS780KLRTR-150B-T: Related family device. Confirm electrical characteristics, transfer function, and any sensitivity or offset differences.

Policy note: Alternates must match package, supply voltage, and sensing range. Verify the output transfer function, calibration method, and any accuracy or bandwidth differences prior to substitution.

Sourcing Tips for Buyers and Program Managers

• Verify the full ordering code (ACS781KLRTR-150B-T) against the AVL and ensure “K” (3.3 V) and “B” (bidirectional) match the electrical requirements and firmware assumptions.
• Align packaging (“TR” tape-and-reel) with your EMS partner’s feeder and lot control preferences.
• For compliance documentation, request the latest RoHS statements and AEC‑Q100 qualification summary from Allegro MicroSystems or authorized distributors.
• If planning multi-year production, confirm lifecycle status and consider securing second-source approvals from the same family where feasible.
• For pricing and lead-time, consult authorized distribution; pricing policies vary and real-time availability should be confirmed through official channels.

Frequently Asked Questions (FAQs)

Q: What does the “B” option denote in ACS781KLRTR-150B-T?
A: “B” indicates bidirectional sensing with a transfer function centered around VCC/2 for ± current measurements.

Q: Is the ACS781KLRTR-150B-T a 3.3 V or 5 V device?
A: The “K” variant operates from a 3.3 V supply. A 5 V option exists for other ordering codes within the family.

Q: Can it measure both AC and DC currents?
A: Yes. As a Hall-effect linear sensor, it supports AC and DC current measurements.

Q: What package is used for this device?
A: LR PSOF-7 (CB-PSSOIC-7), surface-mount, 7 pins.

Q: Is it automotive qualified?
A: The family is AEC‑Q100 qualified (ordering option dependent). Confirm the specific qualification for your exact code.

Q: What is the sensor’s bandwidth and response time?
A: Not specified in datasheet.

Q: What are the sensitivity and absolute accuracy?
A: Not specified in datasheet.

Q: What is the isolation rating between the primary current path and the signal pins?
A: Not specified in datasheet.

Q: Does the analog output require external amplification?
A: No external amplifier is required for basic operation; the device provides a conditioned, ratiometric analog output proportional to the sensed current. System-level filtering or buffering may still be desirable depending on your ADC and noise environment.

Q: Are there pin-compatible alternatives if I only need unidirectional measurement?
A: Yes. The ACS781KLRTR-150U-T is the unidirectional counterpart within the same family/package, with a different output transfer function.

Resources

• Datasheet: https://www.allegromicro.com/-/media/files/datasheets/acs780-781-datasheet.pdf

Summary

The Allegro MicroSystems ACS781KLRTR-150B-T delivers bidirectional ±150 A measurement in a compact LR PSOF-7 package with a simple, ratiometric analog output compatible with 3.3 V systems. Its integrated primary conductor eliminates external shunts and amplifiers, streamlining PCB layout and reducing thermal and BOM complexity. With RoHS compliance and AEC‑Q100 pedigree at the family level, it fits the quality and environmental expectations of modern automotive and industrial platforms. For programs that demand reliable, isolated current sensing with minimal footprint and straightforward signal conditioning, the ACS781KLRTR-150B-T is a robust, design-ready choice. Buyers and sourcing teams can reduce risk by verifying variant codes (“K” and “B”), aligning packaging (“TR”) with assembly needs, and keeping family-compatible alternates on the AVL for continuity.