A new series of pulse load resistors designed to absorb voltage spikes in power electronics used in automotive applications has been developed by Isabellenhütte. These resistors protect downstream components from damage caused by electrical overstress. The PMx series features a flat, space-saving design, high pulse load capacity, rapid heat dissipation and efficient SMD mounting.
Voltage spikes can be triggered by fast switching operations and amplified by inductances, potentially damaging or destroying downstream components. The new PMx pulse load resistors from Isabellenhütte – starting with the PMT (2817) size – safely dissipate these peaks. Based on Isabellenhütte’s SMD (surface mount device) shunt technology, the PMx series is not intended for precision measurement but instead for damping voltage spikes.
The PMT design follows the ISA-PLAN principle: a copper substrate carries a foil made of Isabellenhütte’s proprietary Noventin resistive material. Its high specific resistance enhances pulse load capacity. Voltage peaks are temporarily stored in the resistive material and dissipated as heat through large copper terminals into the PCB.
Depending on the pulse energy, one or more resistors may be required. Multiple resistors can be configured in parallel or series arrays to evenly distribute the load. The number and configuration depend on expected pulse loads, available PCB space and desired resistance values.
In a snubber circuit consisting of a resistor and capacitor, PMx resistors are ideal for use in e-fuses – resettable electronic fuses found in the power supply for a vehicle’s cigarette lighter. When excessive current is drawn, the e-fuse disconnects to protect connected devices. The rapid disconnection activates the snubber circuit. The capacitor initially absorbs the pulse load and discharges through the pulse load resistor, which converts the energy into heat and dissipates it via copper terminals into the PCB.
All resistors in the PMx series are tested in accordance with the AEC-Q200 automotive standard. Within this series, the PMT is currently available in size 2817 with a value range from 50mOhm to 2.5Ohm (R050, R500, 1R00 and 2R50). The PMT is currently in the final phase of the qualification process, with series production scheduled to start at the end of March 2026. In addition to the values listed in the data sheet, customer-specific variants can also be realized within this range. Furthermore, other sizes are available on request: the feasibility of the PMS in 2512 has already been tested and can be implemented at short notice as existing equipment from measurement shunt production can be used. The PMP in size 2010 is also available as an additional option.
According to Isabellenhütte, PMx pulse load resistors are easy to integrate into PCB designs. For higher pulse loads, Isabellenhütte offers support in selecting the appropriate number and type of resistors, as well as in dimensioning, configuration and design-in. Upon request, thermal simulations can be performed to assess heat development and dissipation.