The new HLSR series of current transducers by LEM provide a cost-effective and technically superior alternative to resistive shunt/optocoupler configurations for insulated current measurements up to 50 A. The parts use open-loop Hall-effect current sensing technology, to measure AC, DC or pulsed currents with nominal values of 10, 20, 32, 40 or 50 ARMS. This technology allows the devices to achieve a response time of only 2.5 µs, with very low gain and offset drift over their operating temperature range of -40 to +105 °C.


HLSR transducers deliver their output as an analogue voltage proportional to the primary measured current. Since, in most applications, this voltage will be converted to a digital value by an analogue-to-digital converter, the device is equipped with an internal voltage reference of 1.65 or 2.5 V made available on a dedicated pin. The voltage reference is just one feature of the new ASIC (Application-Specific Integrated Circuit), enabling an accuracy of ±1 % at +25 °C, and ±3.4 % at +105 °C, with a bandwidth of 100 kHz (-3 dB). Versions that operate from either +3.3 or +5 V single supplies are available.