Sources<\/a><\/li>\n<\/ul>\n<\/nav>\n<\/div>\nDirect answer: what is the difference between SPR AVS and PPS?<\/h2>\n Both PPS and AVS let a charger vary its output voltage instead of jumping between fixed levels, but they are different modes with different resolutions and different purposes: PPS offers very fine adjustment and is aimed at fast-charging phones, while AVS offers coarser steps across a much wider voltage range and is aimed at higher-power systems.<\/strong><\/p>\nThe practical distinction is resolution versus range. PPS is designed to track a battery’s voltage closely, so it adjusts in very small steps. AVS is designed to cover a wide span efficiently, so it moves in larger steps but reaches voltages and power levels that PPS does not.<\/p>\n
For any team choosing what to implement, the answer depends on what the product powers \u2014 and getting it wrong means paying for capability nobody uses, or shipping a charger that cannot serve the devices it is sold for.<\/p>\n
Why two adjustable methods exist<\/h2>\n Fixed voltage levels are simple, but they are also wasteful: a device that wants 11V must accept 15V and burn the difference as heat. Adjustable output solves that, and the two methods exist because two different problems needed solving.<\/p>\n
\nThe fast-charging phone problem.<\/strong> As a battery charges, the voltage it wants changes continuously. Matching it closely reduces the energy wasted in the phone’s own charging circuit, which is why fine-grained adjustment was introduced for handsets first.<\/li>\nThe high-power problem.<\/strong> Laptops, docks and higher-power equipment need more voltage and more total power, where the requirement is a wide adjustable span rather than a fine one.<\/li>\nThe efficiency problem at the top of the standard range.<\/strong> Extending adjustable operation into the standard power range lets higher-power products tune their operating point, reducing losses and heat without needing to climb into the highest voltage band.<\/li>\n<\/ul>\nSame idea, two design centres \u2014 and that is why the two modes are not interchangeable.<\/p>\n
What PPS actually does<\/h2>\n PPS stands for Programmable Power Supply, and it is the older of the two, introduced in the USB Power Delivery 3.0 revision.<\/p>\n
\nFine resolution.<\/strong> It adjusts in very small voltage increments \u2014 commonly quoted in tens of millivolts \u2014 which is what lets it track a battery’s changing voltage closely.<\/li>\nCurrent is adjustable too.<\/strong> PPS negotiates both voltage and current in small steps, so the phone can request very specific operating points.<\/li>\nLow-voltage domain.<\/strong> It operates mainly in the lower voltage range, which suits a single cell and a phone’s internal charging architecture.<\/li>\nWho uses it.<\/strong> Fast-charging handsets and the proprietary schemes built on top of it. A phone that advertises PPS support will generally ask for it; a laptop usually will not.<\/li>\n<\/ul>\nThe point of PPS is efficiency inside the device, not raw power at the port.<\/p>\n
What AVS actually does<\/h2>\n AVS stands for Adjustable Voltage Supply, and it arrived with the Extended Power Range before being extended into the standard range.<\/p>\n
\nCoarser resolution, much wider span.<\/strong> AVS moves in substantially larger voltage steps than PPS, trading resolution for reach.<\/li>\nIt spans both power ranges.<\/strong> AVS was introduced for the extended range at higher voltages and was then extended into the standard range, so it covers products from laptop-class power upward.<\/li>\nVoltage-focused.<\/strong> AVS is primarily about choosing an efficient operating voltage rather than tracking a battery’s fine-grained needs.<\/li>\nWho uses it.<\/strong> Higher-power devices \u2014 laptops, AI PCs, docking stations and equipment that benefits from tuned conversion rather than fine battery tracking.<\/li>\n<\/ul>\nThe point of AVS is efficient operation across a wide power range.<\/p>\n
SPR AVS vs PPS, side by side<\/h2>\n This is the table to keep. The two modes differ on almost every axis that matters to a designer.<\/p>\n
\n\n\nAspect<\/th>\n PPS<\/th>\n AVS<\/th>\n<\/tr>\n<\/thead>\n \n\nAdjustment resolution<\/td>\n Very fine, tens of millivolts<\/td>\n Coarser, around 100 mV steps<\/td>\n<\/tr>\n \nVoltage span<\/td>\n Lower voltage domain<\/td>\n Wide: standard range and extended range<\/td>\n<\/tr>\n \nCurrent adjustment<\/td>\n Voltage and current both adjustable<\/td>\n Primarily a voltage mechanism<\/td>\n<\/tr>\n \nPrimary purpose<\/td>\n Track a battery closely to cut loss inside the phone<\/td>\n Choose an efficient operating point across a wide power range<\/td>\n<\/tr>\n \nTypical device<\/td>\n Fast-charging handsets<\/td>\n Laptops, docks, AI PCs, higher-power equipment<\/td>\n<\/tr>\n \nRevision introduced<\/td>\n PD 3.0<\/td>\n PD 3.1 for the extended range; extended into the standard range in PD 3.2<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\nThe one-line summary: PPS optimises finely at low voltage; AVS optimises broadly across voltage ranges.<\/strong><\/p>\nWhy step size matters<\/h2>\n It is tempting to treat a smaller step as simply better. It is not \u2014 step size is a design trade-off, not a score.<\/p>\n
\nSmall steps cost resolution hardware.<\/strong> Finer adjustment needs tighter control and better measurement, which adds cost and complexity to the charger’s control loop.<\/li>\nSmall steps only pay off if the load uses them.<\/strong> A phone’s battery benefits from fine tracking; a laptop’s system rail does not need tens of millivolts of resolution.<\/li>\nLarger steps buy range.<\/strong> Coarser adjustment is what makes a wide voltage span practical, which is exactly what higher-power products need.<\/li>\nThe real currency is wasted heat.<\/strong> Both methods exist to reduce conversion loss; whether that saving is worth the complexity depends entirely on what the load does with it.<\/li>\n<\/ul>\nThat is why “does it support PPS?” is the wrong question for a laptop product, and why AVS support is irrelevant to a phone that charges from a battery rail.<\/p>\n
Where they overlap and where they do not<\/h2>\n Because both vary voltage, buyers often assume one implies the other. They do not.<\/p>\n
\nSeparate modes, separately requested.<\/strong> A device must ask for the mode it wants. Supporting one does not give you the other.<\/li>\nOverlapping voltage territory, different behaviour.<\/strong> In the lower voltage region both can operate, but the resolution and the way they are negotiated differ.<\/li>\nNo automatic substitution.<\/strong> A charger that supports only PPS will not satisfy a device asking for AVS, and the reverse is equally true. In both cases the system falls back to a fixed profile.<\/li>\nFallback is silent.<\/strong> The user sees a slower charge or a lower figure, not an error message \u2014 which is why this shows up as a support ticket rather than a design bug.<\/li>\n<\/ul>\nIf compatibility matters, the specification question is not “which is newer” but “which does the target device actually request”.<\/p>\n100% ATE functional test before shipment \u2014 every unit, not a sample.<\/figcaption><\/figure>\nWhich one your product should implement<\/h2>\n This is the decision the whole article builds toward, and it follows from the load rather than from the specification version.<\/p>\n
\n\n\nProduct<\/th>\n Implement<\/th>\n Why<\/th>\n<\/tr>\n<\/thead>\n \n\nPhone charger, single port<\/td>\n PPS essential; AVS optional<\/td>\n Handsets request PPS; few ask for AVS<\/td>\n<\/tr>\n \nLaptop or AI PC adapter<\/td>\n AVS valuable; PPS largely irrelevant<\/td>\n Wide-range efficiency, no battery tracking needed<\/td>\n<\/tr>\n \nMulti-port charger<\/td>\n Both, allocated per port<\/td>\n One product serves both device classes<\/td>\n<\/tr>\n \nDock or docking station<\/td>\n AVS priority; PPS a bonus<\/td>\n Powers a system, occasionally a phone<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\nThe useful rule: follow the device, not the revision number.<\/strong> Implementing the newer mode on a product whose buyers will never use it adds cost and buys nothing.<\/p>\nImplementing both: cost and complexity<\/h2>\n Supporting both modes is a legitimate choice for multi-port products, but it is not free.<\/p>\n
\nController capability.<\/strong> The controller must support both negotiation paths, which narrows the choice of silicon and can raise unit cost.<\/li>\nFirmware complexity.<\/strong> Two modes mean more protocol states, more edge cases and more test coverage \u2014 and protocol bugs are the expensive kind.<\/li>\nTest coverage.<\/strong> Every mode should be verified at its limits, not just its nominal setting, which multiplies the validation work.<\/li>\nFlexible allocation.<\/strong> A multi-port charger must decide which mode each port offers and re-negotiate when the configuration changes, without causing the visible drop users notice.<\/li>\n<\/ul>\nNone of this is prohibitive. It simply has to be a deliberate decision with the cost attached, rather than a line item someone assumed was included.<\/p>\n
Common specification mistakes<\/h2>\n These four appear constantly in incoming specifications, and each one costs money downstream.<\/p>\n
\nUsing the terms interchangeably.<\/strong> “PPS” and “AVS” describe different modes; a specification that uses one name for the other produces a product that does not do what the buyer expected.<\/li>\nAssuming a phone needs AVS.<\/strong> Handsets request PPS. Paying for AVS on a phone charger is usually money left on the table.<\/li>\nAssuming a laptop needs PPS.<\/strong> Laptop-class devices benefit from AVS; PPS support rarely earns its keep there.<\/li>\nForgetting that the sink must ask.<\/strong> The best charger cannot force a device to use a mode the device does not request, so “our charger supports it” is not the same as “your device will use it”.<\/li>\n<\/ul>\nEach of these is cheap to fix on paper and expensive to fix after tooling.<\/p>\n
What to write in the spec sheet<\/h2>\n The specification should state capability plainly, and resist the temptation to imply certification.<\/p>\n
Write which adjustable modes the product supports, the voltage range and step size for each, which port or ports offer them, and how they behave when the port configuration changes. Then state the protocol as a design claim \u2014 “designed to the USB Power Delivery 3.2 specification including SPR AVS” \u2014 rather than an endorsement.<\/p>\n
That last habit is worth keeping across the whole range. We design to the PD 3.2 specification including SPR AVS, and certification status varies by SKU and production batch, with some earlier units certified to the prior revision. We do not claim USB-IF certification or a TID, and any brand selling under its own name should plan certification per model and market. Our overview of what changed between PD 3.1 and PD 3.2<\/a> covers the background.<\/p>\nBurn-in on the aging rack \u2014 where marginal units are found before they ship.<\/figcaption><\/figure>\nDesigning the control loop<\/h2>\n Behind every adjustable mode is a control loop that has to hold a requested output accurately while the load moves. The mode only appears to work if that loop is stable at both ends of its range.<\/p>\n
\nRegulation accuracy at the extremes.<\/strong> A charger that holds its setpoint in the middle of the range can still drift at the low or high end, which is exactly where devices request unusual levels.<\/li>\nTransient response.<\/strong> When a device changes its request, the output must move quickly without overshoot; slow or ringing transitions are read as instability by the device’s input stage.<\/li>\nStability across the load range.<\/strong> A loop tuned for a laptop’s steady draw can misbehave at a phone’s light load, and vice versa \u2014 which is precisely why a multi-port product is harder than a single-purpose one.<\/li>\nMeasurement discipline.<\/strong> Fine resolution is only meaningful if the charger can measure its own output accurately enough to control it.<\/li>\n<\/ul>\nThese requirements are what separate a specification bullet from a mode a device actually keeps using.<\/p>\n
Bring-up checklist: verifying both modes in the lab<\/h2>\n Most mode-related problems appear in bring-up rather than in design, so the checklist matters as much as the architecture. Test each mode with a real device before trusting a protocol analyser: an analyser confirms that messages were exchanged, but only the device confirms that it stayed in the mode under load.<\/p>\n
\nConfirm the request appears.<\/strong> The device must actually ask for the mode; a charger offering a mode nobody requests proves nothing.<\/li>\nHold it under load.<\/strong> Verify the mode is maintained as the load changes, not only at idle.<\/li>\nTest the limits.<\/strong> Run each mode at the bottom and top of its range, hot and cold.<\/li>\nTest reconfiguration.<\/strong> Add and remove ports, and confirm the allocation behaves predictably rather than erratically.<\/li>\nTest fallback.<\/strong> With a device that does not support the mode, confirm a clean, documented fallback instead of an unstable one.<\/li>\n<\/ul>\nEach of these has a matching line in the specification table below, which is the point: a mode that is claimed but never tested is a support ticket waiting for a customer.<\/p>\n
Adjustable voltage specification table<\/h2>\n \n\n\nParameter<\/th>\n What to record in the specification<\/th>\n Note<\/th>\n<\/tr>\n<\/thead>\n \n\nModes supported<\/td>\n PPS, AVS, or both \u2014 named precisely<\/td>\n Do not use the terms interchangeably<\/td>\n<\/tr>\n \nVoltage range and step<\/td>\n Stated per mode, per port<\/td>\n Resolution and span are the differentiators<\/td>\n<\/tr>\n \nCurrent adjustment<\/td>\n Whether current is adjustable as well as voltage<\/td>\n A key PPS-versus-AVS distinction<\/td>\n<\/tr>\n \nPort allocation<\/td>\n Which ports offer which mode, and in which combinations<\/td>\n Multi-port products change behaviour when reconfigured<\/td>\n<\/tr>\n \nDevice expectations<\/td>\n Which device classes the product is aimed at<\/td>\n The sink must request the mode<\/td>\n<\/tr>\n \nProtocol statement<\/td>\n “Designed to PD 3.2 including SPR AVS”<\/td>\n Capability, not certification<\/td>\n<\/tr>\n \nTest coverage<\/td>\n Each mode verified at its limits, hot and cold<\/td>\n Protocol limits are where bugs hide<\/td>\n<\/tr>\n \nReliability<\/td>\n 100% ATE + burn-in; written change control<\/td>\n Behaviour must not drift between batches<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\nHand assembly and QC \u2014 where labelling and final inspection are done.<\/figcaption><\/figure>\nFrequently asked questions<\/h2>\nWhat is the difference between SPR AVS and PPS?<\/h3>\n PPS adjusts in very fine steps and is aimed at fast-charging phones; AVS adjusts in coarser steps across a much wider voltage range and is aimed at higher-power systems.<\/strong> Both replace fixed voltage levels, but they are separate modes with different resolutions and different target devices.<\/p>\nIs AVS newer and therefore better than PPS?<\/h3>\n It is newer, but not simply better.<\/strong> AVS was introduced for higher-power ranges, so it trades adjustment resolution for range. For a phone, fine PPS tracking is more useful; for a laptop, wide-range AVS is.<\/p>\nDoes a charger that supports PPS also support AVS?<\/h3>\n No, they are separate modes and must each be supported explicitly.<\/strong> A device must request the mode it wants, and a charger that offers only one will fall back to a fixed profile if the device asks for the other.<\/p>\nWhich one should a phone charger implement?<\/h3>\n PPS is essential for a phone charger; AVS is optional.<\/strong> Handsets are the devices that request fine-grained adjustment, and paying for AVS support on a phone-only product is usually unnecessary.<\/p>\nWhich one should a laptop charger implement?<\/h3>\n AVS is the valuable one for laptop-class products; PPS support rarely earns its keep there.<\/strong> A laptop’s system rail does not need the fine resolution that makes PPS useful in a handset.<\/p>\nCan a multi-port charger support both?<\/h3>\n Yes, and it is often the right choice, with each mode allocated per port.<\/strong> The cost is controller capability, firmware complexity and test coverage, and the allocation has to behave predictably as ports are added and removed.<\/p>\nWhy does a device charge more slowly than expected when both support variable voltage?<\/h3>\n Because the system falls back to a fixed profile when the mode the device requests is not offered.<\/strong> That fallback is silent, so the symptom is a slower charge rather than an error.<\/p>\nShould the product page say the charger is PD 3.2 certified?<\/h3>\n No \u2014 write that it is designed to the PD 3.2 specification including SPR AVS, and state certification per model and market.<\/strong> Certification status varies by SKU and batch, and blanket claims create problems.<\/p>\nWhat MOQ and lead time apply for custom chargers with these modes?<\/h3>\n From 200 pcs per model at Paiyi Power, with samples in about a week and first production 5\u20136 weeks after sample approval.<\/strong> Fix which modes you need before tooling; see what changes for 140W laptop chargers<\/a> and why a 140W charger can be limited to 100W<\/a>.<\/p>\n