Samsung · Adaptive Fast Charging
Samsung 15W: the Adaptive Fast Charging era.
Before PPS there was Adaptive Fast Charging — 9V at 1.67A over a USB-A port, borrowed from Quick Charge 2.0. It is the brick in every drawer, it still charges a modern Galaxy, and it is also the reason a modern Galaxy sometimes charges embarrassingly slowly.
What Adaptive Fast Charging actually was
Samsung's 15W adapters (the EP-TA20 generation and its siblings) output two profiles over a USB-A socket: 5V/2A for standard charging and 9V/1.67A for Adaptive Fast Charging — 15.03W. The negotiation is Qualcomm Quick Charge 2.0 in all but name, signalled over the USB-A data pins rather than the CC channel that USB-C uses. It shipped with the Galaxy S6 in 2015 and stayed in the box until USB-C Power Delivery took over.
| Generation | Protocol | Port | Peak |
|---|---|---|---|
| Adaptive Fast Charging | Quick Charge 2.0 derived | USB-A | 15W (9V/1.67A) |
| Super Fast Charging | USB-C PD 3.0 + PPS | USB-C | 25W |
| Super Fast Charging 2.0 | USB-C PD 3.0 + wide PPS | USB-C | 45W |
The two families do not talk to each other. A USB-A Adaptive brick plugged into an S25 with an A-to-C cable negotiates nothing useful and settles at standard USB speed — often under 10W. That is not a fault; the phone has no way to request Quick Charge over a USB-C connector, and it will only ever pull full speed from a PPS-capable USB-C source. Quick Charge explained covers the older standard, and PD vs Quick Charge the split.
Which devices still live at 15W
Plenty, and not all of them are old. Galaxy S6 through S10 and Note 8/9 were 15W devices by design. Budget A-series models, Galaxy Tab A tablets, the Galaxy Watch charging puck and the Buds case all sit at or below 15W today. For those, a 15W adapter is not a downgrade — it is exactly the right size, and a 45W brick would deliver the same 15W with more idle draw and a bigger footprint.
Where 15W becomes a problem is the modern flagship. An S25 asks for 25W and an S25 Ultra for 45W; feeding either from a 15W USB-A brick roughly doubles the time to full. If that describes your drawer, the upgrade path is short: a 25W USB-C adapter for a base phone, a 45W adapter for an Ultra or a Tab S Plus.
What to buy instead
- 15W
Samsung 15W Adaptive Fast Charging Adapter
The original USB-A brick. Correct for Galaxy Watch, Buds, Tab A and any phone from the S6-to-S10 era.
- Output
- 15W max
- Profiles
- 5V/2A, 9V/1.67A
- Port
- 1× USB-A
- Protocol
- Adaptive Fast Charging
- 25W
Samsung 25W Power Adapter
The direct modern replacement: USB-C, PD 3.0, PPS, and the correct ceiling for every base Galaxy phone.
- Output
- 25W PD 3.0
- PPS
- Yes
- Ports
- 1× USB-C
- 30W
Anker 511 Nano 3 30W
A GaN replacement smaller than the 15W brick it retires, with PPS and 30W of ceiling for phones and small tablets.
- Output
- 30W PD
- PPS
- Yes
- Ports
- 1× USB-C
- Tech
- GaN
Further reading: Super Fast Charging explained, Samsung Duo adapters, USB-A vs USB-C, and every Samsung adapter compared.
FAQ
Will a 15W Samsung charger damage a new Galaxy?
No. The phone requests what it can use, so a 15W adapter simply charges it slowly and safely.
Why is my old Samsung charger slower than it used to be?
Almost certainly because it is USB-A. Adaptive Fast Charging cannot be negotiated over a USB-C connector, so a newer phone falls back to standard USB power.
Is Adaptive Fast Charging the same as Quick Charge?
It is derived from Quick Charge 2.0 and uses the same 9V step, which is why many Quick Charge chargers fast-charge older Galaxy phones.
Should I keep a 15W adapter at all?
Yes, for a Galaxy Watch, Buds case, or any accessory that never draws more than a few watts. It is the right size for those jobs.