Diodes Inc. Launches 80 V and 100 V Asynchronous Buck Converters

As vehicles pack in more electronics, from advanced driver assistance systems to infotainment, the 48 V rail has become a critical backbone. To meet those demands, Diodes Incorporated has introduced four asynchronous buck converters that step down voltage efficiently while withstanding the full automotive battery range.

Qualified to AEC-Q100 standards, the devices support input voltages up to 80 V and 100 V, covering the full range of automotive battery operation, including transient conditions such as load dump. Each device integrates a 500 mΩ high-side MOSFET to simplify design and deliver efficient step-down conversion with output currents up to 3.5 A.

The lineup is split into two families: the AP68255Q/AP68355Q (80 V rated) and the AP6A255Q/AP6A355Q (100 V rated). Both families share a constant on-time (COT) control scheme for fast transient response, low output ripple, and reduced external component count, reducing board space and reliability.

The 80 V and 100 V buck converters support 48 V automotive rails, delivering up to 3.5 A output with integrated MOSFETs and AEC-Q100 compliance. Image used courtesy of Diodes Incorporated

AP68255Q and AP68355Q: 80V Solutions

The 80V-rated AP68255Q and AP68355Q are built for point-of-load conversion in applications such as motor controls, telematics, and body electronics. They deliver continuous output currents of 2.5 A and 3.5 A, respectively, with adjustable outputs from 1.2 V to 50 V.

By employing COT control, the converters achieve a nearly constant switching frequency of 300 kHz. This improves line and load transient response, simplifies loop stabilization, and lowers output ripple. A proprietary gate driver reduces ringing at the switch node, which can help maintain fast MOSFET transitions and directly lower high-frequency EMI emissions.

Functional block diagram for the AP68255Q/AP68355Q buck converters. Image used courtesy of Diodes Incorporated

To enhance reliability, the devices feature overcurrent protection with frequency foldback to control thermal rise under fault conditions, and thermal shutdown at 160°C with restart enabled below 140°C. Packaged in thermally enhanced SO-8EP, they are rated for the full -40°C to +125°C automotive range.

AP6A255Q and AP6A355Q: 100V Capability

The AP6A255Q and AP6A355Q are built for environments where voltage conditions are more demanding, extending the input range up to 100 V. Designed for the same 48 V point-of-load applications as their 80 V counterparts, these converters integrate 500 mΩ MOSFETs and use constant on-time control to deliver fast transient response and low ripple. Packaged in SO-8EP, they provide continuous output currents of 2.5 A and 3.5 A, with adjustable outputs from 1.2 V to 50 V, giving designers the headroom and flexibility needed for systems exposed to load dumps or higher transient spikes.

Pin out diagrams for the AP68255Q/AP68355Q and the AP6A255Q/AP6A355Q buck converters. Images used courtesy of Diodes Incorporated

With the added voltage margin, the AP6A255Q and AP6A355Q are well-suited for systems that must ride through load dumps or sharp transients, conditions often seen in commercial and heavy-duty vehicles. They carry over the same EMI reduction strategies and protection circuitry found in the 80 V devices, so engineers can step up to the 100 V range without giving up stability or safety.

Functional Safety and Applications

All four converters are functional and safety-capable, and ISO 26262 documentation is available to support system-level certification. This aligns with the growing need for compliance in automotive electronics. Typical use cases include advanced driver assistance systems, instrument clusters, lighting modules, infotainment, and distributed 48 V rails across the vehicle. With efficiency gains, built-in EMI control, and strong protection features, the devices aim to simplify design-in and reduce the overall bill of materials.

Diodes Incorporated is targeting the 48 V automotive power challenge with its new asynchronous buck converters. These products combine high efficiency, integrated protections, and proven EMI control, giving engineers practical tools to design robust point-of-load converters in demanding automotive environments. The expanded voltage ratings across the two families ensure coverage from mainstream passenger vehicles to heavy-duty platforms.