At Apple's September 10th event, alongside the iPhone 17 series, a small but significant detail appeared on the "40W Dynamic Power Adapter (up to 60W)": the abbreviation AVS (Adjustable Voltage Supply). This quiet addition marks a major shift in Apple's charging strategy. #iPhone17SupportsAVSFastCharging
What Exactly is SPR AVS?
The AVS supported by iPhone 17 is actually SPR AVS (Standard Power Range Adjustable Voltage Supply), a brand-new protocol that was just finalized in the USB PD 3.2 standard introduced at the end of 2024. This isn't just a minor update - it's a complete rethinking of how Apple approaches device charging.
Breaking From Tradition
For years, Apple devices including iPhone 16 have relied on a "fixed voltage charging + internal secondary voltage reduction" model. Meanwhile, Android manufacturers adopted PPS fast charging, which allows for more precise voltage and current adjustments between charger and phone, reducing the need for internal voltage conversion.
The Issues With PPS Charging
While PPS was a step forward, it had significant limitations:
Unrealistic Voltage Stepping
The 20mV voltage steps specified by PPS are practically impossible to achieve due to line losses and charger voltage ripple, both of which exceed this small specification.
Maximum Power Limitations
PPS's "maximum power" concept causes both maximum current and maximum voltage limits to apply simultaneously, often preventing devices from reaching their advertised maximum charging power.
The Origins of AVS Technology
AVS was first introduced in the PD 3.1 EPR (Extended Power Range) specification designed for high-power devices like laptops, capable of delivering up to 48V 5A = 240W. Apple's own MacBook Pro 16-inch was the first mainstream commercial product to utilize AVS technology.
With iPhone 17, Apple is bringing this advanced voltage regulation technology down to the standard power range (under 100W) through the new PD 3.2 SPR AVS specification, making premium charging technology accessible to smartphone users.
What AVS Means for You
All this technical talk might sound complicated, but here's what matters to you as a user:
Cooler Fast Charging
By shifting voltage regulation to the charger, your iPhone stays cooler during charging. This means more consistent charging power and longer sustained high-speed charging.
Longer Battery Lifespan
High temperatures and voltage fluctuations accelerate battery aging. SPR AVS provides more precise low-voltage, high-current power delivery, reducing unnecessary stress on your battery.
No Licensing Fees
AVS is an open protocol with no licensing fees, meaning no additional costs are passed on to consumers. This could lead to more affordable compatible accessories in the market.
The Future of iPhone Charging
With the introduction of SPR AVS support in iPhone 17, Apple is signaling a commitment to improving charging technology while maintaining battery health. This move bridges the gap between fast charging convenience and long-term battery longevity.
As more accessories manufacturers adopt the new standard, we can expect to see a wider range of affordable, high-quality chargers that take full advantage of iPhone 17's advanced charging capabilities.
"SPR AVS represents the next evolution in smartphone charging technology, balancing speed, efficiency, and battery health in a way we haven't seen before."