Alpha and Omega Semiconductor MOSFETs Target AI Server Power Density

AI server power stages have started running into a problem that looks simple on paper but gets ugly fast once the board is real. Current keeps going up, heat has fewer places to escape, and the power devices doing the work are often limited as much by packaging as by the silicon itself. In Intermediate Bus Converters, where engineers are trying to squeeze more conversion capability into tighter thermal envelopes, that packaging detail stops being secondary pretty quickly.

That is where Alpha and Omega Semiconductor’s AONC40202 and AONC68816 come in. The AONC40202 is a 25 V MOSFET and the AONC68816 is an 80 V MOSFET used for high-power-density DC-DC conversion in AI server Intermediate Bus Converter stages. In a typical AI server power architecture, the IBC sits between upstream bus conversion and the downstream point-of-load regulators, so anything that reduces thermal stress in that stage has a direct effect on board density and cooling overhead.

What stands out here is not just the silicon but the way AOS is trying to solve the heat problem around it. Both devices use a DFN 3.3 x 3.3 double-sided cooling source-down package, which shifts attention to how heat leaves the device from both sides instead of relying on a more conventional single-sided path. That matters in dense server power designs because thermal bottlenecks often start at the package interface long before the headline current rating becomes the real limit.

Why Double-Sided Cooling Matters In IBC Stages

The push toward higher rack-level compute density has dragged power hardware along with it. AI servers are not just asking for efficient conversion, they are asking for a lot of it in a very small footprint, and that means the usual tradeoffs around temperature rise, switching losses, and layout parasitics become harder to ignore. A MOSFET can look excellent in isolation and still become a headache once routing, heatsinking, and board area start fighting each other.

AOS is clearly positioning these parts around that tension. The package uses an exposed drain contact with an optimized top-clip design, giving the device a double-sided thermal interface so heat can move more effectively into the cooling structure. According to the company, this approach helps reduce heat generation and thermal stress compared with single-sided cooling devices, which is not hard to understand in server power modules where every extra degree tends to show up somewhere else later.

The quoted top-side thermal resistance is also fairly aggressive for something in this size class. AOS specifies an Rthc-top(max) of 0.9 °C/W, which gives some indication of how much emphasis has gone into extracting heat through the package itself rather than leaving the PCB to do all the work.

Routing Becomes Part Of The Thermal Story

One detail that is easy to overlook is the center-gate layout. It sounds minor until you are staring at a crowded power stage and trying to keep the gate drive path short, clean, and predictable. Once current levels climb and switching edges stay sharp, routing stops being a housekeeping task and becomes part of whether the converter behaves properly.

The source-down structure gives a larger source contact to the PCB, while the center-gate pin layout is intended to make routing easier and minimize the gate driver connection. That should help designers reduce some of the layout awkwardness that often comes with compact high-current stages. It also points to something broader in modern power design. Packaging is no longer just there to hold the die. It is part of the electrical and thermal architecture, and in a lot of AI hardware that line has basically disappeared.

For the AONC40202 specifically, AOS quotes continuous drain current up to 405 A at 25 °C, pulsed drain current of 644 A, and a maximum RDS(ON) of 0.7 mOhms at 10 V. Those are the sort of numbers that make sense in low-voltage, high-current conversion stages where conduction losses can pile up very quickly. The AONC68816, aimed at the higher-voltage side of the pair, carries an 80 V drain-source rating, 119 A continuous drain current at 25 °C, 476 A pulsed drain current, and maximum RDS(ON) of 4.7 mOhms at 10 V.

Two Voltage Classes For Different Parts Of The Server Power Chain

The pairing of a 25 V and an 80 V device is probably the more useful part of this launch than the raw announcement format suggests. These are not two random MOSFETs dropped into the same release. They map onto different voltage needs inside server power conversion, particularly where designers are balancing bus distribution, conversion efficiency, and thermal headroom.

The AONC40202 has a ±12 V gate-source rating, while the AONC68816 is rated to ±20 V. Both devices support a maximum junction temperature of 175 °C, and both are listed with 0.9 °C/W top thermal resistance and 1.1 °C/W bottom thermal resistance. That consistency suggests AOS wants designers to view the package platform itself as a reusable building block, not just a one-off solution around a specific die.

AOS also says the devices use its AlphaSGT silicon technology, paired with the new package to improve thermal behavior, manufacturability, and application reliability. In practice, that combination is what server power designers usually care about anyway. A part can post good electrical performance, but if it complicates assembly, forces awkward routing, or runs too hot once the system is closed up, it rarely stays attractive for long.

The Package Is Doing More Of The Heavy Lifting

There is a clear pattern across power semiconductors right now, especially in infrastructure hardware. Improvements are not coming only from lower on-resistance or slightly better switching characteristics. A lot of the progress is happening in the package, where thermal extraction, current flow, and board integration are being treated as one problem instead of three separate ones.

That is really what these AOS parts are pointing toward. In AI server power, where the density pressure is not going away, a MOSFET package that helps cooling, current handling, and layout at the same time is not just a convenience. It is becoming part of how the converter is made viable in the first place.

Learn more and read the original announcement at www.aosmd.com

Technology Overview

The AONC40202 and AONC68816 are power MOSFETs for AI server DC-DC conversion stages, specifically Intermediate Bus Converter applications. They use DFN 3.3 x 3.3 double-sided cooling source-down packaging to improve heat removal and support high power density. The AONC40202 is rated at 25 V and the AONC68816 is rated at 80 V, with both devices supporting a maximum junction temperature of 175 °C.

Read the AONC40202 datasheet. Read the AONC68816 datasheet.

Frequently Asked Questions

What are the AONC40202 and AONC68816 used for?

They are used in Intermediate Bus Converter DC-DC applications in AI servers and data centers.

What package do the AONC40202 and AONC68816 use?

Both devices are offered in DFN 3.3 x 3.3 double-sided cooling source-down packaging.