HMSR 20-SMS , HMSR20-SMS

LEM HMSR 20-SMS HMSR Series Open-Loop Current Sensor

20A Rated Current x ±50A Measuring Range — High-Precision SOIC-16 Sensor for Industrial and Automotive Applications

LEM HMSR 20-SMS Product Overview

The HMSR 20-SMS is an open-loop Hall effect current transducer from LEM's HMSR series, designed for the electronic measurement of DC, AC, and pulsed currents with galvanic isolation between the primary and secondary circuits. This compact SOIC-16 surface-mount device is designed for PCB mounting with a low profile of just 6 mm. The sensor features a unique design with a low-resistance primary conductor included, dedicated pads to withstand high surge currents, and an integrated EEPROM for programmable internal temperature compensation to ensure accuracy over the full temperature range.

Rated for 20 A nominal with a ±50 A measuring range, it outputs a ratiometric voltage signal of 2.5 V ± 0.8 V (instantaneous) with 0.5% typical accuracy and ±0.5% linearity. Sensitivity is 40 mV/A. Response time is 2 µs and bandwidth is 300 kHz. Supply voltage is +5 V (4.5 to 5.5 V) with a maximum supply current of 26 mA. Operating temperature is -40°C to +125°C. Insulation test voltage is 4.95 kV with an insulation test voltage of 4.95 kVRMS and reinforced insulation capability.

LEM HMSR 20-SMS Key Specifications

LEM HMSR 20-SMS Key Advantages

The HMSR 20-SMS employs open-loop Hall effect technology with a proprietary ASIC, delivering 0.5% typical accuracy and ±0.5% linearity over the entire -40°C to +125°C temperature range. The ±50 A range provides ample headroom for measuring nominal currents up to 20 A with transient overcurrent capability, while the 2 µs response time and 300 kHz bandwidth capture fast-changing motor drive and switching waveforms with high fidelity. The surface-mount SOIC-16 design enables low-cost, automated PCB assembly, saving valuable board space. The sensor features two dedicated overcurrent detection (OCD) outputs – one factory-set threshold and one user-adjustable – providing comprehensive system protection. The reinforced insulation with 4.95 kVRMS test voltage, 8 mm creepage and clearance distances, and immunity to external fields ensure robust safety isolation for demanding applications. The primary conductor can withstand 20 kA surge current bursts (8-20 µs waveform), making it ideal for photovoltaic and power supply applications.

LEM HMSR 20-SMS Typical Applications

Small drives and servo motor drives
HVAC inverters
Home appliances and white goods
Solar inverters and renewable energy systems
Uninterruptible Power Supplies (UPS)
Switched Mode Power Supplies (SMPS)
Power supplies for welding applications

Why Choose the LEM HMSR 20-SMS?

The HMSR 20-SMS combines a 20 A nominal rating with a ±50 A measuring range and 0.5% typical accuracy in a compact, SOIC-16 surface-mount package with +5 V supply. Manufactured by LEM, it delivers stable, accurate, and safe current measurement for demanding industrial, automotive, and renewable energy applications. The open-loop Hall effect design with proprietary ASIC offers excellent linearity, low thermal drift, high immunity to external interference, and dual overcurrent detection outputs, making it a reliable and cost-effective choice for critical systems where measurement integrity and protection are paramount. The sensor complies with IEC 61800-5-1, IEC 62109-1, and IEC 60950-1 safety standards.