Suited for current detection in applications with increased power requirements, such as automotive systems and industrial equipment, ROHM has announced the development of high power ultra-low-ohmic shunt resistors. The PSR series includes the PSR400, which is rated at 4W, and the PSR500, which is rated up to 5W.
Resistors in current detection applications are typically used to detect overcurrent conditions or remaining battery level. And although current sense resistors have been widely adopted in the automotive and industrial sectors, the recent trend towards greater sophistication and computerisation has increased current requirements, leading to a need for high power components. This includes a demand for high accuracy resistors with superior temperature coefficient of resistance (TCR) for stable operation in extreme temperature environments and that feature ultra-low resistance values in order to minimise power consumption.
In response, ROHM utilised high quality resistor technology cultivated for the low-power sector to develop a new lineup of high power low-ohmic shunt resistors. And high-yield precision welding technology made it possible to guarantee high rated power in the 5W class, while a high-performance alloy was adopted in the resistive metal for superior TCR in the low-ohmic region. This ensures sufficient margin even in applications with stringent temperature requirements, such as automotive systems and industrial equipment, while lightening design load.
To support high power and ensure high measurement accuracy even in the ultra-low-ohmic region (0.2mΩ), technology for bonding copper electrodes without variations is required. ROHM employed original precision welding technology to join the resistive metal to thick copper electrodes, achieving high heat capacity with excellent thermal dissipation characteristics. This results in improved power (5W class) along with high productivity.
Generally, as resistance value decreases the TCR increases. In response, ROHM utilised a high-performance alloy material for the resistive metal, ensuring superior TCR even at ultra-low resistances.