explainers
SPR AVS Explained: iPhone 17 Charging in Plain English
Quick answer: SPR AVS (Standard Power Range Adjustable Voltage Supply) is part of the USB Power Delivery 3.2 specification. It lets a charger adjust its output voltage in fine 100mV steps up to 100W, moving voltage conversion out of the phone so fast charging generates less heat. The iPhone 17 family is its first mainstream implementation.
The two words, separately
SPR (Standard Power Range). USB PD splits charging into power tiers: everything up to 100W is SPR; the 100–240W tier above it is EPR (Extended Power Range). Phones, tablets, and most laptops live in SPR.
AVS (Adjustable Voltage Supply). A charging mode where the charger's output voltage is not fixed. The device requests exactly the voltage it wants, and the charger delivers it in 100mV steps. Before PD 3.2, this fine adjustment existed in two other places: PPS (from PD 3.0, 20mV steps) and EPR AVS (from PD 3.1, above 100W, think MacBook-class hardware).
PD 3.2, published by the USB-IF in 2023, brought AVS down into the standard power range. SPR AVS is the combination: adjustable voltage for everyday-wattage devices.
Why it matters: heat moves from phone to charger
A traditional charger offers fixed steps: 5V, 9V, 15V, 20V. When your phone needs something between steps, it converts the difference internally, and that conversion becomes heat inside the device you are holding.
With AVS, the charger does the conversion instead. The phone requests, say, 11.4V instead of settling for 9V or 15V, and the charger supplies it directly. Less heat in the phone means two things in practice: charging stays faster for longer into the battery's charge cycle, and the battery is not cooked as often.
How charging with AVS works, step by step
- You plug in. The phone and charger run the normal USB PD handshake.
- The phone reports its state: battery level, temperature, what it can accept.
- The charger offers an AVS range (for SPR: up to 100W, with the voltage window depending on the power tier).
- The phone picks an exact voltage, in 100mV increments.
- As the battery fills and warms, the phone keeps re-requesting lower current or different voltage; the negotiation never really stops until the battery is full.
SPR AVS vs PPS, honestly
PPS is the older fine-adjustment mode, used by Samsung and most Android fast charging. The differences that matter:
| PPS (PD 3.0) | SPR AVS (PD 3.2) | |
|---|---|---|
| Adjustment | 20mV voltage, 50mA current | 100mV voltage |
| Range | 3.3–21V | 9–20V within SPR tiers |
| Design goal | Direct battery charging (phone-side regulation) | General voltage regulation (charger-side) |
| Who uses it | Samsung Galaxy, many Android | iPhone 17 family first |
One is not "better" — they solve the heat problem differently. PPS gives the phone extremely fine control, at the cost of more complex circuitry on both ends. AVS is coarser but simpler and cheaper to implement, which is part of why PD 3.2 made AVS mandatory territory for new 27–100W charger designs.
The practical consequence for buyers: an iPhone does not use PPS, and a Galaxy does not use AVS. A charger advertising only PPS will still charge an iPhone 17, at standard PD speed, not its fastest. The full side-by-side is our PPS vs SPR AVS comparison.
What Apple actually shipped
The iPhone 17 line supports SPR AVS for wired charging. Apple's 40W Dynamic Power Adapter is the reference implementation. Apple's stated figure is 50% charge in about 20 minutes for the Pro models. MagSafe wireless charging on the same phones tops out at 25W. Daily charging behavior and settings are covered in the iPhone 17 charging guide.
Our SPR AVS charger buying guide covers which adapters are worth buying, including the honest state of third-party AVS claims.
What comes next
Two things are worth watching:
- Android adoption. Samsung and Google flagships still fast-charge over PPS. If that changes (and PD 3.2's certification requirements push in that direction), expect a wave of AVS-capable chargers and falling prices.
- Second-generation Apple adapters. A refresh of the 40W Dynamic Power Adapter would signal how seriously the ecosystem is about to take this.
When either happens, we will update this page with a dated note. Until then, the iPhone 18 charger guide tracks what the next lineup is expected to keep.
FAQ
Is SPR AVS faster than PPS?
For a phone user, the speeds are similar in practice. The difference is architectural: PPS regulates on the phone side with finer steps, AVS regulates in the charger. Both beat fixed-voltage charging on heat.
Do I need a special cable for SPR AVS?
No. Any certified USB-C to USB-C cable rated for the wattage works. AVS changes the protocol between charger and phone, not the cable.
Will an AVS charger fast-charge my Android phone?
It will charge it at standard USB PD speed. Android phones using PPS for their fastest charging negotiate PPS or fall back; an AVS-only charger without PPS support leaves that speed on the table.
Does SPR AVS work with power banks?
In principle yes, once power banks with PD 3.2 AVS output ship. As of this guide's date, verified SPR AVS options are rare; we flag confirmed units in the buying guide rather than trusting box claims.
Last updated: August 22, 2026. We re-check specs and picks on this page as new hardware ships.