What Does A USB Port’s ‘EPR’ Actually Mean? – BGR

Universal Serial Bus, or USB, is often accompanied by abbreviations and short forms when talking about different related technologies that aren’t very popular or widely known. For example, it’s likely not common knowledge what the “C” in a USB-C port means. USB PD, the abbreviation for USB Power Delivery, is slightly more common but is still likely unfamiliar to a lot of folks. Another short form that’s often associated with USB PD but not widely known is EPR. It stands for Extended Power Range, which is a power delivery specification. It indicates that a particular USB port is capable of delivering between 101W and 240W of power.

EPR was introduced in the USB PD 3.1 standard as a follow-up to the Standard Power Range (SPR), which allows for a power delivery of up to 100W using USB ports. It has officially killed the need for massive proprietary power bricks that we get with gaming laptops and other devices that need similar power, such as e-bikes and power tools. Here’s everything you need to know about USB PD EPR (Extended Power Range).

USB PD has been pretty successful at changing the way we charge and power devices. However, its original 100W limit meant it couldn’t be used for high-powered devices. However, EPR has changed that with its 240W limit. It manages to achieve higher power delivery by allowing higher voltage through USB PD connections while keeping the same 5A current as SPR. EPR has introduced three new voltage tiers: 28V, 36V, and 48V, which translate into 140W, 180W, and 240W of power when paired with a 5A current.

However, EPR isn’t limited to these voltage tiers. Similar to how Programmable Power Supply (PPS) extension of USB PD enables voltage selection in steps of 20mV for optimum delivery, EPR comes with an Adjustable Voltage Supply (AVS) feature that also enables voltage selection in steps of 100mV between 15V and 48V. That said, unlike PPS, which was optional and supported current control in addition to voltage control, all USB PD EPR-compatible devices will need to support AVS, but it doesn’t come with current control. Some of the popular products that are currently utilizing EPR’s capabilities include the 16-inch Apple MacBook Pro models released in 2021, 2023, and 2024, Framework Laptop 16, HP Omen Transcend 14, and the Anker Prime 27,650mAh Power Bank.

As EPR is capable of delivering significantly more power than SPR, it also packs more stringent safety features to avoid mishaps. One of its core safety features is that the high power delivery is entirely dependent on the device receiving power. So, unless the device on the receiving end explicitly requests more power, the source can’t force it, meaning there is no risk of a device getting fried because it got more power than it needed. Additionally, all devices in a power delivery connection must support EPR for it to function properly, which includes the source, receiver, and the USB cable. If the USB-C cable is not rated for higher voltage, the power brick won’t supply higher voltage.

Finally, the receiving device must send “Keep Alive” messages to the source to keep the EPR connection active every few milliseconds for the source to keep delivering high voltage. If the “Keep Alive” notifications stop, the power brick drops the voltage to the SPR range of 20V. All in all, despite its high power delivery support, EPR in USB PD ensures you and your devices are always safe, whether you are charging your laptop or powering another device.