IN Brief:
- New 40V, 80V and 100V OptiMOS 7 devices use the 10×12mm TOLL form factor.
- On-resistance values are 0.24mΩ, 0.57mΩ and 0.88mΩ respectively.
- Lower conduction losses help high-current automotive distribution and conversion.
Infineon has expanded its OptiMOS 7 automotive MOSFET range with 40V, 80V and 100V devices in the established 10 by 12mm TOLL package. Their stated on-resistance values are 0.24, 0.57 and 0.88 milliohms respectively, with the manufacturer reporting reductions of 65%, 48% and 37% against specified earlier devices. These are comparisons with particular predecessor parts rather than claims of improvement against every available MOSFET. The components target high-current 12V and 48V vehicle distribution, electric power steering, motor drives and high-to-low-voltage conversion.
Conduction loss is particularly sensitive to on-resistance because it increases with the square of current. At very high currents, a small reduction in milliohms can materially reduce dissipation in a switching element. In a vehicle electrical network, that heat must be managed in an enclosure with limited airflow and changing ambient conditions. Lower loss can give designers the choice of a cooler operating point, additional current capacity or a different number of parallel devices, but the best outcome depends on the real duty cycle.
Infineon’s revised devices use a clip-based interconnection concept intended to improve electrical performance without moving away from the familiar TOLL footprint. That package continuity is helpful where a supplier wants to update an existing board with minimal mechanical disruption. It does not mean a new part is a risk-free drop-in replacement. Pin arrangement, gate drive, switching transitions, thermal impedances and automotive qualification requirements must still be checked against the original circuit and its control firmware.
Switching losses present a different optimisation challenge from conduction losses. The device’s gate charge and capacitances determine how quickly the control circuit can switch it and how much energy is dissipated during a transition. Faster operation can reduce transition losses in some conditions but increase electromagnetic interference or overshoot elsewhere. The combination of improved on-resistance and switching characteristics therefore matters most when evaluated as a system, including connectors, busbars, passive components and the complete current-return path.
Parallel devices add another practical complication. Differences in gate threshold and package resistance can cause unequal current distribution, particularly during switching. Infineon describes a tighter threshold-voltage spread intended to support more balanced sharing.
Engineers should still model thermal coupling and verify transient currents at startup, under steady operation and during faults. A package upgrade cannot overcome a poor board layout that gives one transistor a shorter or cooler current path than its neighbours.
The 12V and 48V environments themselves bring different operating requirements. A 48V system can reduce current compared with an equivalent 12V supply, which can lower wiring losses for high-power accessories. At the same time, fault-protection and insulation decisions must reflect the higher voltage, while motor-control stages remain exposed to inductive transients. Selecting a 40V, 80V or 100V device involves maintaining suitable headroom above normal operating voltage and understanding clamping behaviour during faults.
Cost and manufacturing considerations remain part of the device choice. A lower-resistance MOSFET can sometimes replace two older parallel devices, but that decision changes current distribution, board copper density and the consequences of a single device failure. The bill of materials may improve while the qualification effort grows.
Designers should also test the finished PCB through thermal cycling and manufacturing tolerances, because a footprint-compatible package can still behave differently under solder-joint stress. Device electrical data and assembly-level reliability must be considered together before approving a production change. Any reduction in heat generated must also be verified at the actual switching frequency and duty cycle, rather than inferred only from the nominal on-resistance figure.
The new OptiMOS 7 TOLL products are available, allowing component engineers to compare measured losses and thermal behaviour against existing parts. Their commercial advantage will depend on how readily board makers can translate lower device resistance into a smaller cooling system or lower bill of materials. Evidence from representative load cycles and manufacturing qualification, rather than the headline on-resistance alone, will determine whether the devices justify a redesign or a controlled substitution.
