Linked Questions
38 questions linked to/from How to get more than 100mA from a USB port
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Powering a dc motor from a robotics set with a USB 3.0 PC port
I got my hands on a Gigo microbit robotics set.
It uses a control box to house the microbit. As you can see from the control box specs, it uses 6 AA batteries, but it can also use an external micro-...
- 101
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2
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363
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Question regarding pull-up and battery charger charging current
I'm using this Battery Charger IC.
My question is,
Datasheet mentions, if STAT1, STAT2, and PG# are connected to MCU then We need to connect a pull up do we need to pullup to MCU VCC voltage or ...
user220456
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USB Type-C powering from legacy sources
I'm new to USB Type-C and trying to design a USB-C powered device. After investing some time reading the specification and some application notes, I'm still having problems understanding the big ...
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2
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233
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Why is this "fading" as if the current draw is too high?
I am attempting to build a "dice game" based upon an Arduino Uno.
There will be 5 dice represented by LEDs. To manage the number of LEDs (7 for each die + 1 for an indicator) I have elected -...
- 231
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So can we just draw 500 mA from any USB port without enumeration now?
The USB Type-C Spec R2.0 defines the USB Type-C Current feature, in which the power Sink observes the voltage on the CC pin to determine how much current is available from the Source, which falls into ...
- 28.7k
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3
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USB2 powering 3.3V at 500 mA
I have the above simple requirement, and I'm frankly astonished that I can't find it as a simple chip.
My understandings:
USB2 provides 5V on its power pins;
USB2 assumes 100mA, but will provide ...
- 1,493
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5
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What polyfuses protect USB ports in a typical modern PC?
I would like to know what is the typical rating of a polyfuse used on modern PCs (desktop or laptop) with USB 2.0 and 3.0. TE Connectivity apparently recommended in 2011 that a single USB 2.0 port (...
- 176
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3
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USB 2.0 High-Power Circuit
Is there are special circuit that says to USB socket how much current the device needs?
Our device needs at up to 200mA or little bit more.
I have been searching but I do not find a clear answer ...
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1
answer
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What's the DC voltage range typically tolerated by modern smartphones?
The modern USB charging circuitry of mobile phones is pretty sophisticated. For example they can negotiate higher charging voltages etc.
This question, inspired by a discussion on worldbuilding, is ...
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Usb charger not charging only with vcc and gnd [duplicate]
I want to charge my tablet on the wall. And I have a charger behind the tablet and connected 2 wires to vcc and gnd, the same pins as usb female, it turns out that I can't have more than 10 mA. If I ...
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3
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Why USB wall chargers don't reach their amperage rating? [closed]
recently I bought a power bank that requires 1,6A of charge current. I tried charging it with a 2A Samsung charger, which came with my tablet. Unfortunately it charges very slow. Then I tried another ...
- 123
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2
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Drawing too little current from PC USB
If I connect this very small load (3 LEDs) to a mains to USB adapter, it's fine. Full brightness, great.
I can't even measure the current it's so low.
However, if I connect it to my PC it does 3 ...
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5
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16k
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How to adapt a string of 10 LEDs powered by 3 AA batteries to work off a USB port?
I have a string of Christmas lights made up of 10 warm white LEDs. The lights are connected in parallel (not in series). The string works with 3 AA batteries (that is, 4.5 VDC). And all that stands ...
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1
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LM317 to charge a NImh battery from usb [closed]
Hi want to charge my 4000 mAh 1.2V nimh cell battery simply, I do not use them very often.
So I wanted to plug this kind of voltage regulator
which I think is like that : https://en.wikipedia.org/...
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6
answers
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USB Power - The basics
I am new to designing something to be powered by USB. Ideally It can either be plugged in to an adapter to a UK wall plug, or a powered USB port on another device. I have the circuit design in place ...
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2
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USB powering batteries without OS support?
On a bare-metal project I have in mind, I would like to know if I can avoid to implement the multiple USB specs (O/E/xHCI) and still benefit from usb charging my battery. It will run on a almost ...
- 119
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2
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How much current will I get from the 5V rail of a Teensy 3.2 powered over USB? [duplicate]
The microcontroller in question is a Teensy 3.2. My understanding is that the most current that you can get from a standard computer USB port is ~180mA; how much of that will current devices attached ...
- 125
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1
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How to configure USB OTG as power supply
I have an ARM computer with an USB 2.0 OTG port, and I want to use it as 5V 100mA power supply (to drive a couple of leds). However, when I connect a load (LED+resistor) via an OTG cable, the power is ...
- 25.8k
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5
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How does a USB 2.0 Wall Charger negotiate current output?
I'm trying to use a mobile phone charger for my projects, and want a high current output. I have read this, however my measurements show something else.
Here is a link to the Battery Charging ...
- 2,766
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4
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6k
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USB PC Current Limit
I want to build a USB device that can draw 1A.
Some of the PCs at my office can supply 1A, some only 800mA. The USB 2.0 specification says a device can only draw up to 500mA.
I cannot build a ...
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3
answers
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Connecting a higher-current power supply to a lithium-ion charger will damage the battery. Why?
I am not asking how the battery gets damaged, because that answer is straightfoward.
What I am asking is why lithium-ion chargers allow batteries to be damaged by excessive charge current in the ...
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3
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103k
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What is the ideal way to handle data pins D+ and D- on a USB power adapter to be compatible with fast charging on devices?
I have found that many USB wall chargers use a resistive voltage divider to set the D+ and D- pins to a specific voltage, usually between 2 and 3 volts. Other USB wall chargers short the D+ and D- ...
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2
answers
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Make a tea mug heater with a USB power source
For a school project, I have to make a mug heater which draws its power from a computer's USB port, such as this one. I don't mean one that boils the tea, but one that keeps it warm-ish, at at least ...
- 215
2
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2
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471
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connect LEDs to USB keyboard – but they turn off after a second
I have a USB keyboard. As I work many times in the darkness, I put some LEDs into the keyboard case. I connected two pairs of yellow standard LEDs serially to the USB power lines (Vcc and ground, pin ...
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1
answer
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How does my phone get charged via laptop USB port at lesser current (compared to wall charger) [duplicate]
Today's typical smartphone chargers are rated at 5 Volt & 1+ Ampere. The laptop USB can supply 500mA 100mA.
Why is it safe to charge the phone with 1/2 the rated current?
Is it like a slow ...
- 177
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2
answers
1k
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Convert low power USB to high power USB in car stereo.
Could I connect the D+ and D- to my car stereo's USB input, then connect the red and brown (+/-) to a 2amp cigarette plu'sg USB? My issue is that the USB in the head unit is low power and doesn't ...
- 21
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3
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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 ...
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2
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1
answer
3k
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Risk of overloading a usb charger
I just bought this product: "Jackson PT1USB" as an attemp to get a portable charger for my netbook, ipad 2 and smartphone.
Now I am bit worried after reading in the product "total connected load to ...
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2
answers
596
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Can you charge a battery to run a device at 5V from the USB port?
Say you had a device that requires 5VDC to operate. It can actually run safely at about 4.8VDC. It normally runs off of USB power but I would like to rig it up to run off of a battery. Would it be ...
- 3,745
6
votes
2
answers
4k
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Critique of my Data logger's Power circuit design
I am laying out my first full device, a fairly simple sensor-data logger, with these specs in mind:
I'm running microcontroller and sensor @ 3.3V, with load varying from 10 mA to 400 mA
device will ...
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