If you bought an HP laptop in the last three or four years — a Spectre x360, an Envy 16, a ZBook Firefly, or a recent EliteBook — there's a good chance your charger doesn't have the round blue-tip plug that HP used for over a decade. Instead, it has a USB-C connector. It looks like the same port you use for your phone, your external drive, and your monitor. And that's both the best thing about it and the source of more confusion than any other charging technology HP has ever shipped.
The TPN-LA31 is HP's 100W USB-C Power Delivery adapter — one of the most common USB-C chargers in HP's current lineup. It's not a barrel adapter. It doesn't use Smart Pin. It communicates with your laptop using an industry-standard protocol called USB Power Delivery, and understanding how that protocol works — and where it doesn't — is the difference between a charger that "just works" and one that leaves you with a dead laptop and no idea why.
USB Power Delivery: The Protocol That Replaced the Blue Tip
For two decades, HP laptop charging was mechanically simple. The adapter put out 19.5V DC. The laptop drew whatever current it needed. The Smart Pin on the blue-tip connector told the laptop the adapter's wattage, and that was the entire communication — a one-way identification signal. If the plug fit, and the voltage was right, and the wattage was sufficient, charging worked.
USB-C Power Delivery is fundamentally different. When you plug a USB-C charger into a USB-C laptop, the two devices negotiate. The charger doesn't start delivering power immediately. Instead, it sends a set of available voltage and current profiles — 5V, 9V, 12V, 15V, 20V, each at a specific maximum current. The laptop selects the profile it wants. Only after this handshake does power flow. If the negotiation fails — because the charger doesn't support the voltage the laptop needs, or the cable is passive and doesn't support PD communication, or the laptop's USB-C port isn't wired for charging at all — nothing happens. No charging light. No power indicator. The laptop acts as if the charger isn't connected.
This is why a USB-C charger that works perfectly with one laptop can do absolutely nothing when plugged into another. It's not broken. It's just that the negotiation didn't succeed, and unlike a barrel adapter — where a physical fit almost always means electrical compatibility — USB-C offers no such guarantee.
Not All USB-C Ports Accept Power
This is the single most common point of confusion for HP laptop users, and it's worth stating clearly: the presence of a USB-C port on your laptop does not mean that port supports charging. Many HP laptops have USB-C ports that are data-only, or that support DisplayPort video output but not power input. The port's capabilities are determined by how HP wired it internally, and the only reliable way to know is to check your laptop's specifications.
HP typically marks charging-capable USB-C ports with a small battery icon or a lightning bolt symbol next to the port. But this is not universal, and the icon can be hard to see. A more reliable method: look at the specifications page for your specific laptop model on HP's support website. If the power section lists a USB-C adapter as the included charger, or if the port specifications mention "Power Delivery" or "PD," the port supports charging. If the specifications are silent on USB-C charging, assume the port is data-only.
One practical test: plug your laptop into its original USB-C charger. If it charges, the port works. If you then plug in a different USB-C charger that meets the wattage requirement and it doesn't charge, the issue is with the charger or the cable — not the port. If the original charger doesn't work either, the port may have been disabled in BIOS, or it may have a hardware fault.
Why 100W Matters for the Laptops That Use This Adapter
The TPN-LA31 delivers 100W — 20V at 5A — which is the maximum power level defined by the USB PD 3.0 standard before the introduction of Extended Power Range (EPR) in PD 3.1. This puts it at the top of the standard USB-C PD range, and HP pairs it with laptops that need that headroom: Spectre x360 models with discrete graphics or high-resolution OLED displays, ZBook Firefly mobile workstations, Envy 17 configurations with dedicated GPUs, and larger Pavilion Plus models.
A 100W adapter will also charge laptops that need less power — 45W, 65W, or 90W — without any risk. The laptop requests only the power it needs, and the adapter delivers exactly that. This is one of the genuinely useful properties of USB-C PD: you can carry one 100W charger and use it across multiple laptops, as long as they all support USB-C charging and none of them require more than 100W.
The reverse is not true. If your laptop requires 100W — as the Spectre x360 16 with discrete graphics does — and you connect a 65W USB-C charger, the laptop will recognize the lower power availability and may respond by throttling performance, charging the battery more slowly, or refusing to charge under load. HP laptops with higher power requirements will typically display a warning when a lower-wattage adapter is connected. This is the same logic as the barrel adapter world, but implemented through PD negotiation rather than Smart Pin identification.
The Cable Matters More Than You Think
USB-C PD negotiation involves the cable as an active participant. A standard USB-C cable that works fine for data transfer or charging a phone may not support 100W power delivery. USB-C cables are rated for specific current levels: 3A (60W at 20V) and 5A (100W at 20V). If you plug a 100W-capable adapter into a 100W-capable laptop using a 3A-rated cable, the negotiation will cap at 60W. The laptop will charge, but slowly, and you may not realize why.
The TPN-LA31's cable is fixed to the adapter body and rated for the full 5A. This is important because it eliminates the cable as a variable — you can't accidentally use the wrong cable with this adapter. But if you connect the adapter through a USB-C extension cable, a hub, or a dock, any of those intermediate devices may limit the power delivery to 60W or lower. For maximum charging speed, connect the adapter directly to the laptop.
When USB-C Charging Goes Wrong: Common Failure Modes
USB-C PD charging failures fall into a few predictable categories. Knowing which one you're dealing with saves time and prevents unnecessary replacements.
No response at all. The laptop shows no sign of recognizing the charger — no charging light, no power indicator, no change in battery status. This usually means the PD negotiation failed. Check whether the USB-C cable is fully seated. Try a different USB-C port on the laptop if one is available. Check whether the laptop's BIOS has a "USB-C Power Delivery" or "USB Charging" setting that may have been disabled — this is more common on business laptops with IT-managed BIOS configurations.
Slow charging or "plugged in, not charging" status. The laptop recognizes the charger but won't charge the battery, or charges extremely slowly. This can happen when the laptop is under heavy load and the charger's available power is being consumed entirely by the system, leaving nothing for the battery. It can also indicate that the charger is delivering less than the laptop expects — either because the charger is underpowered, the cable is limiting current, or the charger is connected through a hub that restricts power delivery.
Intermittent charging. The laptop charges, stops, charges again, stops again. This is often a cable issue — the USB-C plug may be slightly loose, or the cable may have internal damage that causes the PD negotiation to drop and restart. USB-C connectors are more prone to this than barrel connectors because they have more pins in a smaller space, and a tiny amount of debris or wear on the contacts can disrupt the communication channel.
Charger works with one laptop but not another. This is almost always a PD profile mismatch. The charger may not support the voltage that the second laptop requests. For example, some laptops require 15V or 20V for charging and won't accept 9V or 12V even if the wattage is available. The TPN-LA31 supports all standard PD profiles up to 20V, so it should work with any USB-C PD laptop that doesn't require more than 100W — but older or lower-quality USB-C chargers may have a more limited profile set.
Traveling With a USB-C Charger: What's Different
One of the real advantages of USB-C PD charging is travel flexibility. The TPN-LA31 accepts 100-240V AC input, so it works worldwide with a plug adapter. But the more interesting travel benefit is that you can potentially reduce the number of chargers you carry. A 100W USB-C adapter can charge your HP laptop, your phone, your tablet, and your wireless earbuds — all from the same charger, one at a time.
There are practical limits. The TPN-LA31 has a single USB-C port. It can only charge one device at a time. If you're traveling with multiple devices and need to charge them simultaneously, a multi-port GaN charger may be a better travel companion, even if it means carrying a separate charger for the road. The TPN-LA31 is better suited as a stationary charger — one at your desk, one at home — rather than the single charger you carry everywhere.
For airline power outlets, the same caveat applies as with barrel adapters: most in-seat outlets cap at 75W, and a 100W adapter may trip the outlet's circuit protection. Plan to work from battery during flights and charge at the airport or hotel.
Barrel to USB-C: The Transition That's Still Happening
If you're coming from an older HP laptop with a barrel jack, the switch to USB-C charging can feel like a downgrade at first. The blue-tip barrel connector was robust, mechanically simple, and nearly impossible to plug in wrong. USB-C feels fragile by comparison, and the fact that a charger can work with one laptop and not another — even though the plug fits — is genuinely confusing.
But the transition is happening for good reasons. USB-C PD is an industry standard, not an HP proprietary technology. This means the adapter ecosystem is larger and more competitive. It means you can charge your laptop with a third-party charger, a power bank, or even a monitor with USB-C power delivery — options that never existed in the barrel adapter world. And it means HP can design thinner laptops, because a USB-C port takes up less internal space than a barrel jack and its associated power circuitry.
The TPN-LA31 represents the mature end of this transition — a 100W adapter built on years of USB-C PD refinement. It's not the most exciting piece of technology, but it's one of the most important ones in your bag, and understanding how it works is the difference between a laptop that's always ready and one that leaves you stranded.
Frequently Asked Questions
How do I know if my HP laptop's USB-C port supports charging?
Check your laptop's specifications on HP's support website. Look for "Power Delivery," "PD," or "USB-C charging" in the port descriptions. If your laptop shipped with a USB-C adapter, the port supports charging. If your laptop shipped with a barrel adapter and has a USB-C port, that port may be data-only — verify before buying a USB-C charger.
Can I use this adapter with a MacBook or a Dell laptop?
Yes, as long as the laptop supports USB-C PD charging at 100W or below. The USB PD standard is the same across brands. A MacBook Air, MacBook Pro 13-inch, Dell XPS 13, or Lenovo ThinkPad X1 Carbon with USB-C charging will work with this adapter. Some laptops require more than 100W (MacBook Pro 16-inch, Dell XPS 17) — this adapter will charge them, but slowly, and may not sustain full-performance operation.
Why does my laptop charge through one USB-C port but not the other?
HP often designs laptops with multiple USB-C ports where only one or two support charging. The charging-capable port is typically marked with a battery or lightning bolt icon. If neither port works, check the BIOS for a USB-C Power Delivery setting and ensure it's enabled. Some business laptops allow IT administrators to disable USB-C charging as a security measure.
Can I use a USB-C phone charger to charge my laptop in an emergency?
Only if the phone charger supports USB PD and can deliver at least the minimum voltage your laptop requires — typically 15V or 20V. A standard 5V phone charger will not charge a laptop, even if the USB-C plug fits. Some newer phone chargers that support USB PD with 20V output (like 65W GaN chargers) can charge laptops, but at reduced speed. Check the charger's specifications before trying.
Is it safe to leave the adapter plugged in all the time?
Yes, within reason. Modern laptops manage their batteries intelligently and will stop charging when the battery reaches full capacity. However, keeping the battery at 100% continuously for months can accelerate battery aging. If you primarily use your laptop at a desk and rarely run on battery, consider enabling HP's battery health management feature (if available in your BIOS) to limit the maximum charge to 80%.
The adapter gets warm — should I be concerned?
Warm is normal. A 100W adapter converting AC to DC generates waste heat, and it will feel warm during use — especially when charging a laptop that's also running, which means the adapter is delivering power and the laptop is drawing it simultaneously. The adapter should not be uncomfortably hot to hold. If it is, ensure it has ventilation and is not covered by anything. A burning smell or visible deformation is a sign to stop using the adapter immediately.
What's the difference between USB PD 3.0 and PD 3.1?
USB PD 3.0 supports up to 100W (20V at 5A). USB PD 3.1 introduces Extended Power Range (EPR), which supports up to 240W (48V at 5A). The TPN-LA31 is a PD 3.0 adapter. It will work with PD 3.1 laptops, but only at up to 100W. If your laptop requires more than 100W, you need a PD 3.1 adapter or a barrel-style charger — depending on what your laptop's manufacturer provides.
Can I use a USB-C power bank to charge my laptop instead of this adapter?
Yes, if the power bank supports USB PD output at 20V and can deliver at least the wattage your laptop requires. A 65W USB-C PD power bank will charge a laptop that needs 65W or less. A 100W power bank will charge most USB-C laptops at full speed. Keep in mind that laptop batteries are typically 40-60Wh, and a 100Wh power bank (the largest allowed on airplanes) will provide roughly one full charge to most laptops.
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