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Will It Work? · Guide

USB PD and PPS: what each one does

By Bulan Sarkar, founder of ElectronicsInfoline (since 2000)

Charger boxes print “PD”, “PD 3.0”, “PPS” and wattages, and phone makers sometimes say their top speed needs one of them. This explains, from the USB-IF's own documents, what each one does and when the difference shows up.

USB PD gives fixed voltages (5, 9, 15, 20 V, plus 28, 36, 48 V since PD 3.1): the device picks one. PPS (Programmable Power Supply, part of PD 3.0) lets the device set the voltage itself in 20 mV steps and the current limit in 50 mA steps. A PPS charger still offers the fixed profiles, so it works with every PD device.

Fixed profiles: the charger offers, the device picks

A PD charger offers fixed voltages of 5, 9, 15 and 20 V, depending on its power rating (USB-IF). It lists them, the device asks for one, and the charger switches.

How a USB PD charger and device agree on powerThe charger lists its profiles (5 V 3 A, 9 V 3 A, 15 V 3 A, 20 V 3 A); the device asks for one; the charger agrees and switches to it. Until then the port stays at 5 V.ChargerDevice1. Here is what I offer5 V × 3 A = 15 W9 V × 3 A = 27 W15 V × 3 A = 45 W20 V × 3 A = 60 W2. I want this one3. Agreed: switching now
Figure 1. USB Power Delivery in three messages: the charger lists what it offers, the device asks for one profile, the charger agrees and changes voltage. The profile list here is an example label.

PPS: the device sets the voltage

With PPS the charger's output voltage is adjustable in 20 mV steps and its current limit in 50 mA steps (USB-IF). The phone can ask for just the voltage its battery needs at that moment, rather than the nearest fixed step. Certified USB Fast Chargers support it (USB-IF).

Fixed PD voltages against PPSFixed PD jumps between 5, 9, 15, 20 V. PPS lets the device set the voltage in 20 mV steps across a range.5 V10 V15 V20 VFixed PD profilesPPS: 20 mV stepswhat the device asks for, over a charge
Figure 2. Fixed profiles jump between 5, 9, 15, 20 V. With PPS the device sets the voltage itself in 20 mV steps and the current limit in 50 mA steps (USB-IF). The ramp is drawn coarser than 20 mV so it shows.

Above 20 V: PD 3.1

PD 3.1 added 28, 36 and 48 V for more than 100 W (USB-IF), and an adjustable mode from 15 V up to the charger's top voltage in 100 mV steps (USB-IF). These are for devices that need more than 100 W, and they need a 240 W cable.

USB PD fixed voltagesFixed voltages 5, 9, 15, 20 V, then 28, 36, 48 V added in PD 3.1 for 140, 180, 240 W.5 V9 V15 V20 V28 V140 W36 V180 W48 V240 Wup to 100 W■ before PD 3.1■ added in PD 3.1 (needs a 240 W cable)
Figure 3. USB-IF: PD 3.1 added 28, 36, 48 V to the earlier 5, 9, 15, 20 V, for up to 140, 180, 240 W. Before that, PD stopped at 100 W (20 V on a 5 A cable).

Tips and tricks

  • If the phone maker says its top speed needs PPS, look for “PPS” and a voltage range on the charger’s label.
  • A PPS range has its own current limit, printed next to it. A range at 3 A gives less power than the same range at 5 A.
  • A charger without PPS is not wasted on a PPS phone: it charges on the fixed profiles, just not at the top speed.
  • Wattage on the front is the total; the label lines are what a single device can get.

What we would do

Check the phone maker's charging page first. If it names PPS for the top speed, buy a charger whose label shows a PPS range covering that power at the current shown. If it names plain USB PD, any PD charger with the right voltage line and enough amps does the job.

Then run your charger label and phone through the charger and cable checker.

Questions people ask

Is PPS the same as USB PD? PPS is part of USB Power Delivery: the USB-IF calls it the Programmable Power Supply feature of the PD 3.0 specification. A PPS charger is a PD charger that also offers adjustable ranges.

Will a PPS charger work with a phone that has no PPS? Yes. The charger still lists its fixed profiles, and a phone without PPS picks one of those.

What does “Certified USB Fast Charger” mean? It is a USB-IF certification name for chargers; the USB-IF says Certified USB Fast Chargers support PPS. A certified charger is named with its wattage, for example “Certified USB Fast Charger 100W”.

What is the adjustable voltage in PD 3.1? PD 3.1 added an adjustable mode for the higher-power range: from 15 V up to the charger's top fixed voltage (28, 36, 48 V), set in 100 mV steps. It is a different feature from PPS, which works in 20 mV steps.

Sources

Each figure on this page is quoted from the source below or worked out from them. Sources checked , each quote read again against the source in a second pass.

  1. USB-IF, USB-IF Introduces Fast Charging to Expand its Certified USB Charger Initiative (press release, January 8, 2018): Certified USB Fast Chargers support the Programmable Power Supply (PPS) feature of the USB Power Delivery 3.0 specification. usb.org/sites/default/files/2018-08/certified_usb_fast_charg…
  2. USB-IF, USB Power Delivery (USB Developer Days 2019, Taipei, slide deck): What is Programmable Power Supply (PPS) ... The Source output voltage adjustable in 20 mV steps ... The Source output current limit adjustable in 50 mA steps usb.org/sites/default/files/D2T2-1%20-%20USB%20Power%20Deliv…
  3. USB-IF, USB Power Delivery (USB Developer Days 2019, Taipei, slide deck): Fixed voltage outputs: 5 V, 9 V, 15 V and 20 V depending on PDP usb.org/sites/default/files/D2T2-1%20-%20USB%20Power%20Deliv…
  4. USB-IF, USB Promoter Group Announces USB Power Delivery Specification Revision 3.1 (Developer Update, May 26, 2021): A choice of three new fixed voltages: 28V (above 100W), 36V (above 140W) and 48V (above 180W) joining previously defined 5V, 9V, 15V and 20V fixed voltages. usb.org/sites/default/files/2021-05/USB%20PG%20USB%20PD%203.…
  5. USB-IF, USB Promoter Group Announces USB Power Delivery Specification Revision 3.1 (Developer Update, May 26, 2021): A new adjustable voltage mode enabling a range from 15V to one of three maximum voltages (28V, 36V, or 48V) depending on the available power allowing the device being powered to request specific voltages to a 100 mV resolution. usb.org/sites/default/files/2021-05/USB%20PG%20USB%20PD%203.…
  6. USB-IF, USB Charger (USB Power Delivery) | USB-IF: An adjustable voltage supply mode allows the device being powered an ability to request intermediate voltages between 15V and up to the maximum available fixed voltage of the charger. usb.org/usb-charger-pd
  7. USB-IF, USB-IF Integrators List Marketing Name Guidance (January 2023): Certified USB Charger [Wattage] • Certified USB Fast Charger [Wattage] Examples "Certified USB Fast Charger 100W" usb.org/sites/default/files/usb-if_integrators_list_marketin…
  8. USB-IF, USB Promoter Group Announces USB Power Delivery Specification Revision 3.1 (Developer Update, May 26, 2021): The USB Type-C specification has also been updated with Release 2.1 to define 240W cable requirements, and with the updated USB PD protocol and power supply definition, this extends the applicability of USB PD to a large number of applications where 100W wasn't adequate. usb.org/sites/default/files/2021-05/USB%20PG%20USB%20PD%203.…

Author: Bulan Sarkar · Report an error

Numbers here are quoted from standards bodies and makers, or worked out from them. Nothing on this page was measured or tested by us.