Shunt resistors contribute to miniaturisation in power

Recent years have seen an increased requirement in the automotive and industrial fields for lower power consumption in higher power applications. This in turn requires shunt resistors that support high power and high accuracy current detection to achieve a high efficiency operation in a variety of applications. ROHM’s GMR and PSR series shunt resistors provide highly accurate current protection – even at high temperatures, making them ideal for high power applications in the automotive, industrial and consumer sectors.

The newly developed GMR320 series is offered in a resistance value range from 5mΩ to 100mΩ and a rated power of 10W, making them ideal for automotive engine ECUs and headlamps as well as motors and power supplies for industrial equipment and home appliances. The structure and optimised materials allow the GMR320 series to reduce surface temperature rise by 23% over standard products, ensuring high ruggedness against overcurrent load – even though it has the smallest size among 10W class resistors in the market.

In addition, a high-performance metal alloy of the resistive material provides low Temperature Coefficient of Resistance (TCR) that makes reliable and highly accurate current detection possible even in the low resistance values.

On the other hand, for the PSR series, which is widely used as high-power shunt resistor, the maximum rated power has been increased by up to 15W and the TCR value has been also improved by applying the terminal temperature derating method. Ultra-low resistances value from 0.1mΩ to 3.0mΩ can be offered, and higher rated power and high accuracy of current detection is provided in a compact package, contributing to greater miniaturisation in automotive and industrial applications same as GMR series.

Furthermore, from October 2021, thermal simulation models for shunt resistors will be available on ROHM’s website. This will make it possible to perform simulations before designing the actual products, even in high power applications where thermal design is particularly difficult, reducing design man-hours considerably.

ROHM is committed to continuing to expand its resistor lineup (a founding product) from low to high power and provide various tools and other technical support to contribute to the evolution of vehicles and industrial equipment by great energy savings and miniaturisation.

ROHM newly developed the GMR320 series of high-power low-ohmic shunt resistors while extending the rated power of the high power ultra-low-ohmic PSR series to cover the high-power range up to 15W. Furthermore, both series are qualified under the AEC-Q200 automotive reliability standard for passive components, ensuring a maximum operating temperature of 170°C that provides high reliability even in vehicle environments where temperatures can be particularly severe, such as in the engine compartment.

Design support tools that significantly reduce design load

From October 2021, thermal simulation models for shunt resistors will be available on ROHM’s website. These models allow thermal design (which is a major issue during application design) to be simulated in advance, reducing design man-hours.

ROHM also offers current detection solutions combining ICs with discrete components that contribute to greater circuit efficiency and miniaturisation. As an example, for motor drive circuits that require current detection for protection and control, adopting our class-leading low noise operational amplifiers together with shunt resistors makes it possible to achieve high accuracy current detection.