Gate Drivers Engineered for New Era in Power Electronics

Oct. 27, 2023

Check out some of the latest gate-driver IC developments in this installment of the Products of the Week.

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Dual-Channel Gate-Driver ICs Up the Isolation

Infineon enhanced the galvanic isolation in its latest generation of dual-channel gate-driver ICs. Now they’re suited for everything from switch-mode power supplies (SMPS) in data centers and telecom, solar inverters, and energy-storage systems to industrial motor drives, battery-powered power tools, and fast chargers for EVs.

Useful in hard- and soft-switching topologies with primary- or secondary-side control, the EiceDriver 2EDi family outputs source and sink current of 1 A/2 A or 4 A/8 A, delivering high efficiency and reliability in harsh conditions over a wide temperature range. They also add configurable dead time and, to protect the power device from harm, shoot-through protection. CMTI is more than 150 V/ns.

Engineered for everything from silicon MOSFETs to silicon carbide (SiC) and gallium nitride (GaN) in half- or full-bridge configurations, the gate drivers are equipped with its “coreless transformer” technology for galvanic isolation. By removing unused pins from the package used in its predecessors, the chips can deliver higher channel-to-channel isolation ratings and give customers more flexibility in placing the gate driver on the PCB.

As usual for gate drivers in its class, the family has a short propagation delay (under 40 ns). Accurate timing also lends itself to driving power MOSFETs that are placed in parallel to share the current load.

Managing electrical noise in compact, lightweight power systems is a constant challenge. The chips have active output clamping circuitry to clamp output noise fast even if the channel is inactive. As a result, it’s possible to prevent dangerous shoot-through events during boot-strapped startup while the gate supply voltage remains under undervoltage lockout (UVLO). Fast clamping of the output along with high reverse-current capability (5 A) enhances reliability.

UVLO works even at the startup of power supply to prevent malfunctions. The latest generation of isolated gate-driver ICs, which are housed in space-saving leaded DSO and leadless LGA packages, initiate the protection feature significantly faster than ever before, which means the power supply itself can also start up faster while removing the risk of mains power-transformer saturation.

The DSO variant comes in 14- and 16-pin configurations, with “narrow body” and “wide body” packages for additional channel-to-channel creepage. The LGA variants have 5- × 5-mm or 4- × 4-mm dimensions.

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Change never comes easy in the world of power electronics.

To achieve higher power densities, the latest 3.3 kW switched-mode power supplies (SMPS) are adopting silicon-carbide (SiC) power MOSFETs in the totem-pole PFC stage and gallium-nitride (GaN) power switches in high-voltage DC-DC converter stages. While silicon MOSFETs and IGBTs are always improving, these new semiconductor materials are upping the ante. That’s largely thanks to their ability to manipulate more power at higher voltages and currents than silicon while losing less to heat.

These new switching technologies bring to the table fast switching speeds and other unique properties that lend themselves to use in EV traction inverters and DC-DC converters, uninterruptible power supplies (UPS) in data centers, industrial motor drives, and solar and other types of inverters for renewable-powered grids.

To bring the best out of SiC and GaN power devices, you need to carefully control and drive them. Digital control of both the power-factor-correction (PFC) and DC-DC stages is critical to improving power efficiency and robustness, as is the use of optimal gate-driver ICs.

To that end, semiconductor firms are rolling out more optimized isolated gate-driver ICs that can better manage the pros and cons of SiC and GaN power switches and even the latest silicon or superjunction (SJ) MOSFETs and IGBTs.

Choosing the right gate driver is critical because of the role it plays in power electronics. They act as the (usually isolated) interface between the microcontroller (MCU) or analog controllers—which pump out the pulse-width-modulation (PWM) signals to control a power supply’s duty cycle, frequency, dead time, and phase-shift—and the power MOSFET. It’s standard practice to put the MCU on the low-voltage side of a power supply so that it stays away from the noise and transient voltages that the FETs experience.

The gate driver must supply sufficient current to turn the FET on and off as fast as possible. Doing so shortens the dead time between the on and off phases and reduces power losses that can add up in the interim.

As the demands for gate drivers change rapidly in the era of SiC and GaN, semiconductor firms are rising to the challenge. They’re developing gate-driver ICs with higher sink and source currents, faster propagation delay, and more robust galvanic isolation that can fit into smaller form factors.In this product roundup, we review some of the latest gate driver ICs to hit the market.