⚡How to Build a Safe, Reliable and High-Efficiency PD Charger？

With the widespread adoption of USB Type-C and USB Power Delivery (PD) technologies, the power output of fast charging devices is constantly increasing (30W, 65W, and even 140W+). At such high power densities, chargers not only need to be small and fast, but also safe and stable.

To ensure the reliability of the entire power path, we have designed a complete protection scheme for PD fast charging.👇

PD fast charging protection MOSFET for PD charger USB-C <a rel=ESD protection" class="wp-image-16148"/>

The following is a detailed analysis of the protective functions of our electronic components for PD fast charging.

🔸AC Input Terminal: GDT Gas Discharge Tube

The AC input terminal is most vulnerable to lightning surges and strong interference spikes from the power grid. Adding a GDT gas discharge tube before the rectifier stage allows for rapid conduction during high-energy transients, bypassing dangerous voltages to ground, thus protecting:

  • APFC Front-End Circuit
  • Main Power MOSFET
  • Subsequent Transformer and Controller

Advantages of the gas discharge tube include:

  • Extremely high surge withstand capability
  • Low leakage current, does not affect normal operation

🔸Main Power Stage: High-Efficiency MOSFETs Ensure Conversion Efficiency

In fast-charging power supplies, MOSFETs are key components affecting energy efficiency and temperature rise. We use MOSFETs in the following locations:

✔ Primary Switch

MOSFETs used for the primary switch must possess:

  • Low Rds(on) → Reduces switching losses
  • High withstand voltage → Typically 650V/700V or similar ratings
  • Fast switching characteristics → Improves APFC + PWM system efficiency

✔ Synchronous Rectifier (SR) Switch

Using low on-resistance MOSFETs can achieve:

  • Significantly reduced conduction losses
  • Improved energy efficiency of 65W/100W PD output
  • Reduced temperature rise, reducing heat dissipation pressure

🔸Type-C Interface

The Type-C interface, being the point of direct contact for end users, is easily affected by electrostatic discharge (ESD), transient plugging/unplugging, and incorrect connections.

✔ ESD Protection Devices (TVS)

  • We deploy ESD protection on sensitive lines such as CC/SBU/DP/DM/VBUS:
  • <1pF ultra-low capacitance (does not affect the integrity of high-speed interface signals)
  • IEC 61000-4-2 Level 4 protection
  • Fast response speed

✔ Load Switch MOS (VBUS Switch)

  • Responsible for turning the PD output on/off. Features:
  • Low Rds(on) → Reduces VBUS voltage drop
  • Supports high current (3A/5A)
  • Used for overcurrent protection, soft start, thermal shutdown, and other mechanisms.

🛡️By combining the above components, the following effects can be achieved in PD fast charging:

  • High Reliability: Input surges no longer threaten the upstream APFC and MOS.
  • High Efficiency: SR MOS reduces heat loss and improves overall conversion efficiency.
  • High Safety: The Type-C port has comprehensive ESD + OCP protection.
  • Extended Product Lifespan: Reduces component stress and minimizes after-sales risks.

🔍 More Protection Solutions
Looking for complete protection components for PD fast charging, USB-C ports, adapters, and system-level designs?
Explore our full range of surge, ESD, MOSFET, and circuit-level protection solutions here:
👉 https://en.semiware.com/application/