This new series combines a revised electrode structure with an optimized device design that improves heat dissipation to the printed circuit board where the resistor is mounted. The result is a mounting area 39% smaller than that of conventional 4W products. Furthermore, this new series can withstand overcurrent loads and offers stable current sensing accuracy even when unexpected loads exceeding the rated power are applied, contributing to improved system-level reliability.
Shunt resistors are used in the industrial and automotive markets for current sensing. Particularly in the automotive sector, increased functionality results in a greater number of motors and ECUs, but at the same time, the mounting area for these applications is inherently limited. As a result, high-density assembly is on the rise, driving demand for components that incorporate compact power shunt resistors.
To meet these needs, ROHM launched the GMR100 series in 2017. These are power shunt resistors in a 6.4 mm × 3.2 mm package (type 2512 shunt), which have since been well received in the automotive and industrial equipment markets that demand very stringent temperature requirements. The GMR50 series being launched now has been developed to meet the demand for greater miniaturization and higher power than conventional products. In addition to expanding its shunt resistor range, ROHM, as a comprehensive semiconductor manufacturer, will continue to strengthen its technical support, such as thermal simulations to assist industrial and automotive customers, and will offer unique solutions alongside the power devices and operational amplifiers currently under development.
(Fig. 2)
Key Features
1. The original heat dissipation structure achieves the industry's highest power rating along with improved durability under overcurrent loads.
To increase power rating while simultaneously reducing size, it is necessary to ensure long-term reliability against self-heating. In response, ROHM has improved heat dissipation by revising the electrode structure and optimizing the device design. For example, when using a 5 mΩ, 2 W product, ROHM achieved a 57% reduction in surface temperature rise compared to conventional 5025-sized resistors.
1) High power rating contributes to greater space savings.
The GMR50 series offers superior heat dissipation, guaranteeing the industry's highest power rating (4 W) in the 5.0 mm × 2.5 mm size (2010 type package) at a terminal temperature of TK=90°C (and 3 W at TK=110°C).
The improved power rating allows the use of smaller shunt resistors in the 4 W class, reducing the mounting area by 39% and contributing to greater space savings.
2) Excellent durability enables stable current sensing.
Shunt resistors are used in current sensing circuits, but stable current sensing is also necessary even when a large current flows through the resistor due to a fault in the sensing target or to faults or short circuits to ground.
This latest series provides greater durability against overcurrent loads than conventional products, resulting in minimal resistance change even when the overcurrent exceeds rated flows for stable current sensing accuracy.
3) ROHM can provide unique solutions (as a comprehensive semiconductor manufacturer)
. In addition to shunt resistors, ROHM can provide a wide range of products, from integrated circuits to power devices, as well as advanced technical support such as thermal simulation.
For example, with the newly developed GMR50 series mounted on a printed circuit board, it is possible to simulate the surface temperature rise compared to conventional ROHM products. The simulation results suggest that it is able to suppress the temperature rise in circuits using two conventional 5025-size resistors in parallel, even when mounted as a single unit.
(Fig. 3)
2. Excellent resistance temperature coefficient, even in the low resistance region.
This new series uses a high-performance metal alloy as the resistive element to provide a superior resistance temperature coefficient (RTC), even in the low resistance region. For example, 0 to +25 ppm/°C is guaranteed for the 5 mΩ resistor.
This enables highly accurate current sensing that is less affected by changes in ambient temperature, thus contributing to improved application reliability.
(Fig. 4)
Availability: immediate
Range
The range has been expanded to include the 5.0 mm × 2.5 mm package (type 2010) of the GMR50 series in addition to the existing 6.4 mm × 3.2 mm package (type 2512) of the GMR100 series.
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ROHM resistor selection chart
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