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0
votes
1answer
53 views

Is a PD controller necessary if VBUS is always >5V?

I'm trying to implement a board that will use USB-C Power Delivery. We want to operate with 20V 5A input. If we know the source will always be at 20V, is it necessary to put a PD controller on the ...
0
votes
1answer
54 views

USB Port Amperage

So I have built a Benchtop Power Supply out of an old computer power supply to power and test misc. gadgets I have created. I would like to attach 2 salvaged USB ports from a junked computer to the 5v ...
0
votes
0answers
38 views

Default behavior of a USB device in the presence of 5v [duplicate]

This is a follow on from this question Given a home made USB charger that simply provides 5 volts across the GND and VCC pins of a USB port, what should the default behavior be of any mobile device (...
0
votes
0answers
55 views

Minimum current to charge a 5v device? [duplicate]

I'm trying to use a DC-DC converter to charge a mobile phone. This is the converter....TRACO 12v-5v converter The converter is relatively low power, (5w) and can supply a maximum of 1amp. Testing ...
1
vote
2answers
96 views

How to efficiently trigger QC and convert it to constant 5V and a peak of 5A?

Introduction For a university project I started working on RGB LED Shutter glasses, which are based on the idea of a kickstarter by Macetech. However, these glasses miss some features I was looking ...
0
votes
1answer
96 views

Quick charge negotiation device [duplicate]

I'd like some advice on how I can negotiate a Qualcomm Quick Charger up to a certain voltage. I have a "dumb" appliance which usually uses its own transformer/"wall wart" at 12V 1A. I also have a USB ...
0
votes
3answers
84 views

USB current draw and CE marking

We have developed a docking station product which charges multiple devices simultaneously, and currently ships with a 5V, 3A barrel jack adaptor. We are looking to move this over to USB power, and ...
0
votes
1answer
88 views

Power bank multiple output currents

I've been working on a simple power bank project that's been built using Li-ion batteries, the batteries are rated 3.3 V. I've implemented a charge controller which can efficiently charge the power ...
0
votes
1answer
28 views

Powering dual 5VDC, 2.4A USB ports via a switch in vehicle

I have an illuminated 2 port usb charger that plugs into a cigarette lighter/accessory socket in a car. The face of the charger is flat and sits flush when inserted into the cigarette lighter/...
6
votes
4answers
4k views

Why doesn't my computer USB port break when I plug in a 2A device?

For typical AC to DC power adapters, I understand that the device draws the current it needs from the adapter. If it pulls more than the adapter can supply, this can cause overheating and lead to ...
0
votes
3answers
116 views

I'm planning to put lots of phone chargers on one circuit, how to calculate this

This would be primarily for samsung S7 devices. Would like to be able to charge, say, 256 of them. They will work in groups of 16, trying to design the power flow of this. Was imagining that each ...
1
vote
2answers
500 views

DIY Android Auto Power Booster

first time using StackExchange so please be gentle (and pardon my ignorance with wiring and USB standards). I'm trying to create a USB power booster that allows Android Auto to function over my car's ...
1
vote
2answers
183 views

Can I charge my AC rechargeable hearing aid batteries via USB PD with converter?

I hope you'll be able to help. First of all this is a bit of a complex one that I'm struggling with. I wear hearing aids, both of which use removable, rechargeable batteries, charged only by a charger ...
0
votes
2answers
83 views

What are the limits for a USB PD charger and device to settle on a charging profile?

I've got a laptop which charges through USB Power Delivery. The charger supports the following profiles: 5V x 3A 9V x 3A 12V x 3A 15V x 3A 20V x 3.25A I know USB PD devices and chargers enumerate ...
0
votes
2answers
277 views

USB charger limits: 9 V, 1.7 A but only 5 V, 2 A? Not exactly anti-proportional

The standard USB charger from the box of a smartphone (model EP-TA20EWE) has the following limitations: 9 V at 1.67 A = about 15 W. 5 V at 2.0 A = 10 W. Should that charger not be able to reach 3 A ...
1
vote
2answers
655 views

Can I high current charge port transfer data at the same time?

I was reading about USB charging ports and how a host can tell the device what current it may draw: How do USB charging and "smart" charging ports (e.g. Anker's PowerIQ) work? Do all ...
3
votes
1answer
327 views

Can Type-C device be configured as “Sourcing Device” without Power Delivery protocol?

I'm designing a device, that will be connected to various Android devices with either microUSB B or USB C receptables (in order to make it futureproof) and will be exposing some irrevelant ICs to the ...
1
vote
1answer
42 views

Powerbanks with multiple ports rated at different Amperage: technical difference?

My SBS TTCB100002UF powerbank, which charges with 10 W of input power, has two USB ports rated at different outputs: 2.1 A and 1.0 A for output. The 1.0 A-labelled port also delivered 2 A, just like ...
1
vote
1answer
92 views

Can I connect 2 USB ports to a device with a Y cable and therefore double the current output?

Say I have a portable power bank with two USB ports providing 2a each. If I connect both the ports to the same device using a Y cable would I therefore have an output of 4a?
-2
votes
1answer
330 views

Does a QuickCharge 3.0 USB charger charge my Nexus 5X just as fast as a 5V/3A charger? [closed]

I've got a Nexus 5X phone which does not support QuickCharge, but it does support 'fast charging' through a 5V/3A USB Type C charger. Normally I charge it with a Type C 5V/3A charger, and a USB Type ...
0
votes
1answer
700 views

Make 'smart' USB Dedicated Charging Port [duplicate]

I would like to create a circuit that is able to charge any USB connected device from my 5V rail with 1A current limit. There are many different USB devices, asking different kinds of currents, so: 1)...
0
votes
1answer
1k views

Floating D+ and D- on a USB Charger

currently I have a problem with an USB Charging Plug (from china). There are some designs, where the D+ and D- line is shorted together, in other there are held to 2.7V. On my plug on the table, ...
0
votes
1answer
286 views

What problems exist in making USB splitter cables?

I have a use case for a mobile phone and OTG device that all use the micro USB connectors. Typically the OTG device is designed to be plugged directly into the phone, however this prevents the phone ...
3
votes
2answers
5k views

Best way to test a USB wall charger for output current

USB chargers are tricky. Or at least they are when you don't follow the standards. I have a device that uses 5V to charge a battery. The device has a USB socket, with the idea of connecting it to any ...
0
votes
1answer
138 views

safe USB caharging cable LED mod

is it safe to add an activity LED to an USB charging cable in parallel? full story: I've recently bought one of these glowing USB charging cables, but it died after a few months of use so now i am ...
0
votes
2answers
1k views

USB charger - tell the phone it can draw more power [duplicate]

I have 8A 6port usb charger. It has two ports marked as fast charing, and the phone here actually charges faster than in the two other ports. When I dismantled it, all the USBs were on the same power ...
0
votes
1answer
343 views

Can I make a dual output USB charger by connecting two USB sockets in parallel?

I bought an old wall plug that outputs 5VDC and maximum 2.5 A and thought I'd make a USB charger. Considering the amperage I figured I might as well put two outputs, but now I'm not sure how to ...
1
vote
1answer
691 views

USB Connector Current Rating for Charging

I have heard it mentioned that the current rating for a USB charger is dependent on the current rating of the USB port itself; ie a Type A connector has to be rated for 2A on a charger that says it ...
0
votes
3answers
2k views

Can I charge a 12v toy with USB? [closed]

I have this small palm sized toy drone. It uses a 'charger' which houses 8 AA alkaline batteries. The charger plugs into the drone and the charger is activated by a toggle switch. I want to replace ...
0
votes
1answer
283 views

I want to design an adapter from USB to 4.3v and 70mA

How can I design an adapter between USB and 4.3v and 70mA. Can I just connect a USB cable to my device that takes 4.3v and 70mA? Is it likely to damage the device? I'm looking for a better than 50% ...
-1
votes
3answers
186 views

5V USB booster only giving 4.92V

I have a 0.9V-5V to 5V USB booster but I am only getting 4.92V. The product I'm using to needs 5V to charge. Is there anyway I can boost to voltage to 5.1V or 5.2V?
0
votes
1answer
106 views

Changing old batteries in handheld device and replacing the charger

I need them to power a small handheld soldering iron, which had an old battery that died. The original battery was NiCD 1200 mAh 2.4v I am replacing them with 2 NiMH-520rs in series First question: ...
-1
votes
1answer
128 views

simple USB charging

I have a battery project that i want to charge via USB at around 300mA. If just using a wall wart then everything is easypeasy, but I want to make it compatible with a computer as well. What I've done ...
-1
votes
2answers
4k views

What is the maximum Power that Smartphones charge with? 2400mAh? [closed]

I have seen chargers rated at up to 2400mA, so I wonder, whats the max that Smartphones will accept while charging? I ask because I want to buy a charger that is able to supply the absolute max my ...
-2
votes
1answer
71 views

oDevice to measure power available from charging point [closed]

When charging, I know that USB socket that you plug your microUSB cable into will charge your device at SOME rate. But that rate varies wildly, depending on the original source of the power (high ...
0
votes
2answers
5k views

what size supercapacitor do i need to replace 4 3.7v 2400mah batteries?

I have a 5v 2amp external usb battery pack that dis/charges 4 18650 vape style batteries. Each is 3.7v 2500mah. My Question is, what size supercapacitor would replace the batteries, preferably more ...
1
vote
1answer
232 views

Making a universal USB charger

I would like to make an universal USB charger. I have a 5V, 2A max generator and I can not find any electronic assembly to create a Dedicated Charging Port able to charge Samsung, Apple and other ...
22
votes
2answers
35k views

How does a USB C port provide the power to charge laptops?

I've heard about laptops such as the new Chromebooks that are charged via a wall charger that connects to a USB-C port. I'm quite happy that this will supposedly standardize laptop chargers but I'm a ...
0
votes
1answer
872 views

Cheap and easy way to power MCU from Li-Ion, and keep it powered during charging

What is the cheap and easy way of powering MCU from Li-Ion battery, with automatic 3.3V regulator disconnect while charging, to properly charge the battery? I've came up with something like this: Is ...
23
votes
8answers
37k views

How do USB charging and “smart” charging ports (e.g. Anker's PowerIQ) work?

Software engineer with a hobbyist understanding of EE here. I've noticed lately lots of claims from producers of USB battery packs that their ports are "smart" and "identify the device" to "deliver ...
0
votes
1answer
126 views

USB Host Power Enumeration

Background: I am designing a "smart charger" for my personal Android phone. I would like it to be able to adjust the amount of (or turn off) power going to the phone. Planned Implementation: The "...
-1
votes
2answers
141 views

How many USB cables does it take to charge a mobile? [closed]

Loads of devices these days have USB links to enable you to link them to the PC - eBooks, MP3 players, tablets and so on. To save cable the same USB cable also has a link to a plug that goes straight ...
0
votes
1answer
201 views

Inductive phone charger mod - doesn't work with battery too close?

I am experiencing a strange issue, likely because I do not fully understand the technology I am trying to make play nice together, but maybe someone here can shed some light on it. I have an HTC Evo ...
0
votes
3answers
3k views

Three-prong / USB power outlets in wooden desk [closed]

I am trying to mount a strip of three-prong outlets and a strip of USB charging outlets on an old wooden desk. I can handle the carpentry aspect, but I am struggling with the electrical aspect. I ...
0
votes
2answers
5k views

Multiple 2A USB Mains powered chargers [closed]

I'd like to know why there are no mains-powered chargers that can charge multiple usb devices at, say, 2A and 1A? I'm after something that can charge 2 tablets that ask for 2A and 2 phones on 1A, so ...
6
votes
2answers
6k views

3.3V Power Failover Supply with USB Li-Ion Charger

I am currently designing a "3.3V@500mA Power Failover Supply with Integrated USB Li-Ion Charger" for a uC project. I want the circuit to draw power straight from USB power when available & switch ...
5
votes
3answers
3k views

What happens if you charge a laptop using it's USB power?

To play a joke on this question, we came up with the following image on the Super User Chat. Of course this will not work, but now my question is: What happens if you charge a laptop using it's USB ...