MCP14T0517: Simplifying Isolated Power Supply Design for Modern Power Electronics

Why Isolated Bias Supplies Matter

Modern power electronics systems increasingly rely on higher voltages, faster switching speeds and wide-bandgap power devices such as SiC MOSFETs. These systems often require isolated bias supplies to power circuits located across an isolation barrier.

In practical designs, isolated bias rails may be needed for isolated gate drivers, isolated communication interfaces, isolated sensing circuits or other galvanically isolated control functions. Building these rails usually requires a compact transformer-based power stage. The MCP14T0517 is designed to simplify that part of the system.

The MCP14T0517 helps simplify isolated bias-supply design by integrating the push-pull transformer driver function, key protection features, synchronization capability and automotive-grade operation into a compact SOT-23-6 package.

What Is the MCP14T0517?

The MCP14T0517 is a push-pull transformer driver for isolated power supplies. It is designed for compact isolated supplies operating from a 3.0V to 5.5V DC input. The device integrates two power MOSFETs and drives a center-tapped transformer using complementary output switching.

Key Features at a Glance

Where the Device Sits in the Design

The MCP14T0517 is not used to directly drive the main power FET. Instead, it sits on the low-voltage side of the system and drives the primary of a center-tapped transformer. The transformer transfers energy across the isolation barrier, and the secondary-side rectification and filtering generates isolated bias rails for the downstream isolated circuit.

How It Drives the Transformer

Inside the MCP14T0517, an oscillator and gate-drive circuit generate complementary switching outputs. These outputs drive the two integrated power MOSFETs connected to the primary of a center-tapped transformer.

As each side of the primary is driven alternately, energy is transferred through the transformer. The secondary-side circuit then rectifies and filters the transformer output to create the isolated output rails required by the target circuit.

The device also controls the slew rate of the switch voltages and uses oscillator dithering to help support low-EMI design goals. Designers can also supply an external switching clock through the synchronization input when multiple transformer drivers need synchronization or when harmonic placement is important.

Why It Is Useful for Isolated Gate-Driver Bias

Many power stages using Si MOSFETs, IGBTs and SiC MOSFETs require isolated gate-driver bias rails. The MCP14T0517 helps generate those rails from a low-voltage input supply. This makes the device useful in systems where the gate driver must remain isolated from the primary-side controller or low-voltage logic.

Application Fit

• On-board chargers (OBC): Provides isolated bias rails for high-voltage power-stage gate drivers
• High-power DC-DC converters: Supports compact isolated bias generation in high-efficiency power-conversion systems
• EV charging infrastructure: Helps generate the isolated supplies needed around high-voltage switching and control sections
• Data center and telecom power: Supports compact isolated auxiliary supplies in dense power architectures
• Renewable energy and energy storage: Useful in solar inverter, energy storage and DC/AC or DC/DC conversion designs
• Isolated communications and sensing: Can generate isolated power for interfaces such as CAN, LIN, USB or isolated sensing circuitry

Design Flexibility: Low EMI or Smaller Magnetics

The MCP14T0517 family offers two switching-frequency options, so designers can optimize the isolated supply for the application. The 150 kHz option is intended for designs that prioritize lower EMI, while the 450 kHz option supports smaller transformer size. The external clock input also allows multiple devices to be synchronized.

Do You Need a Transformer Driver?

MCP14T0517 is typically used when a design has only a low-voltage supply (3.3V or 5V) but requires isolated bias rails for gate drivers, communications interfaces or sensing circuits.

You may not need MCP14T0517 if:

• Your design does not require galvanic isolation
• An isolated DC/DC converter is already generating the required bias rails
• The gate-driver solution already includes power-generation functionality

The MCP14T0517 generates the isolated power rails required by the isolated gate driver, while the isolated gate driver provides the gate-drive current used to control the SiC MOSFET.

Conclusion

The MCP14T0517 is a compact transformer driver that helps engineers build isolated power supplies for modern power electronics systems. By integrating the push-pull drive switches and adding protection features such as UVLO, current limiting, thermal shutdown, dead-time generation and soft start, the device reduces design complexity while supporting robust isolated bias generation.

For systems using isolated gate drivers, isolated communications or isolated sensing circuits, the MCP14T0517 provides a practical way to generate the isolated rails required by the design. It is especially well suited for automotive, industrial, renewable energy, data center and high-voltage power-conversion applications.

For more information, please visit the MCP14T0517 web page.