TI “Transforms” Isolated Power Modules with Multichip Packaging

Isolated Bias-Supply Modules Spanning from EVs to AI

Soundarapandian said IsoShield could make a difference in EVs, which are rapidly shifting from 400 V to 800 V — and even 1,000+ V — architectures to enable ultra-fast charging and longer range. By removing the need for a dedicated DC-DC converter and the components tied to it, IsoShield-based bias-supply modules can reduce the size, cost, and weight of traction inverters, onboard chargers, and the like.

At APEC, TI showed the modules in a SiC-based, automotive-grade, 300-kW traction inverter reference design.

The same pressures to maximize power density are emerging within data centers. At NVIDIA’s GTC this month, TI demoed a 30-kW power-supply unit for AI servers — a level that would have been associated with an entire rack a couple of years ago.

At the same time, server racks such as those based on NVIDIA’s Blackwell GPUs are already consuming at least 120 kW per rack. Meanwhile, power companies are preparing for NVIDIA’s Rubin Ultra superchip, which could potentially drive rack power up to 600 kW by the end of the year.

This escalation is forcing more power to be packed into tight, increasingly hot form factors spanning racks, servers, and circuit boards inside them. As traditional power-distribution approaches reach their limits with AI, NVIDIA and the likes of Google, Meta, and Microsoft are working to adopt 400-V, 800-V, and other high-voltage DC (HVDC) architectures to reduce distribution losses and bulky wiring. All of this high-voltage hardware, however, depends on robust galvanic isolation at the device level to maintain safety and reliability.

With rising power densities across the board, SiC and gallium nitride (GaN) are increasingly replacing silicon MOSFETs due to their faster switching speeds and higher efficiency. In AI server power supplies above 10 kW, the power-factor-correction (PFC) stages are moving to more advanced multilevel topologies, such as three-level flying-capacitor interleaved PFC. They frequently use fast-switching SiC to reach peak efficiencies above 99% while reducing passive component size and handling the heat in data centers.

TI said IsoShield is designed to address some of the issues encountered with these wide-bandgap semiconductors. The faster switching of SiC and GaN creates rapid voltage (dv/dt) transients. These transients can cause EMI, typically linked to ringing from parasitic inductances and capacitances within the power circuit, which may lead to unintended turn-on or damaging shoot-through currents. As a result, SiC and GaN tend to require tighter control of gate-drive voltages compared to silicon MOSFETs.

By integrating the transformer and isolation, IsoShield enables a common-mode transient immunity (CMTI) of 250 V/ns. This means the bias supply can withstand extreme voltage swings caused by the switch, even in the noisy insides of traction inverters and server power supplies. These bias supplies must deliver stable voltage rails with low noise and fast transient response to avoid overshoot and undershoot, which can reduce efficiency and reliability.

The UCC34141-Q1 is specifically designed to supply bias power to gate drivers in front of SiC or other high-voltage power-switching devices. In general, SiC requires positive gate-drive voltages (of around +15 V) to rapidly turn on, and negative voltage (of around -5 V) to rapidly turn off and make sure they stay off. The DC-DC power module is paired with external voltage dividers to set the positive and negative outputs to the gate drivers.

The UCC14240-Q1 features a wide input voltage range of 5.5 to 20 V that works with varying, unregulated outputs — as in the case of EV battery packs and energy storage systems (ESS) — or fixed, regulated outputs.

The power module can output 1.5 W at up to 85°C, giving it enough to power a gate driver in a distributed architecture. Such an architecture assigns a dedicated, local, and well-regulated bias supply to each gate driver, improving robustness and reliability by eliminating single points of failure.

For instance, in a traction inverter with six power switches, if one isolated bias supply fails, the remaining bias supplies can continue powering their paired gate drivers. As long as the other switches continue operating, the EV motor can decelerate and shut down safely.

The advanced control architecture in the UCC34141-Q1 also reduces output capacitance so that it can respond in time to fast-changing load currents, which are increasingly prevalent in electric motors as well as GPUs and other AI-class chips in data centers.

The industrial-grade UCC33420 is more compact and comes with more than 3 kV RMS. It’s designed to be used in isolated bias supplies based on GaN, among other areas.