Hello
First I am sorry for my English, because I am from Czech Republic and I am 13 years old. >:(
My question Is-I need to power something about 70 LEDs from one Pin so I get tranzistor to pin5 and to collector external loboratory power supply to power Leds and to emmitor LEDs Itself. But external power supply is powered from 230VAC and I need this project to power from Powerbank
My power bank has got 5V 2,1A OUTPUT.
So my question Is: can I get 2,1A-electric that need Atmega from 5V pin if I get powerbank to USB conector or if Is there betwen 5V pin and USB some protectin diode ar fuse or something else with limit max current
Thanks
You are limited by the on-board regulator if the incoming power goes to Vin.
If you have an external 5V supply, route that direct to the LEDs as well as to the USB power
if you want - you don't have to pass current through the Arduino board at all.
2.1A is too large for the Arduino, I think the polyfuse will kick in well before that.
But I need this project portable or move it and i need to power it only with powerbank without any ither power suplly only with power bank with will be pluged- in USB conector on UNO, is there eny fuse or diode betwen 5V and USB?
Because regulator is only on vin but it isnt betwen usb becouse usb has got 5V
Děkuji
Between the Uno's USB port and its internal 5V bus there is a 500 mA fuse and an FDN340P FET switch.
If there is no VIN applied to the Uno, then the FET switch should be ON. When ON, its max drain current rating is spec'd at 2A, continuous current.
If you never plan to apply a voltage to VIN and instead you will only power the Uno via the USB 5V, you could try shorting the fuse and shorting out the FET from Drain to Source. This would allow you to get as much current as you'd like to the Uno's 5V bus.
But I haven't looked at the board layout. You might cook a trace. Nor do I know the current-rating of the contacts on Uno's tiny USB connector. (If you plug/unplug during high-current draw, you run the risk of arcing at the contacts and thus contact degradation).
SO ONLY DO THIS AT YOUR OWN RISK!!!
Instead, I'd recommend building a box into which you can mount the Uno and which has a larger USB connector (one more friendly to high-current). Then within this box route the USB 5V from this larger connector to the Uno (one wire) and to your LEDs (another wire).
jcanderson:
Between the Uno's USB port and its internal 5V bus there is a 500 mA fuse and an FDN340P FET switch.Nor do I know the current-rating of the contacts on Uno's tiny USB connector.
Just realized I'd been thinking of the Nano's tiny USB connector when I wrote this. Uno's might be more robust. You'd need to check.
Still, I'd recommend (as did MarkT above) that you not power 2.1 amps to your LEDs from Uno's board.
How much current is each LED pulling?
You're against the limits of what an Uno can put out without modification. The PTC fuse could be wired around, which would keep that from limiting you.
Another approach, maybe a modified USB cable so power and ground could be brought directly out to Vcc and Gnd? But this could be bad if you then plugged it computer's USB...
Much better to use an external supply to power the LEDs. The Arduino boards are not designed to provide power for a large number of LEDs.
marouncz:
But I need this project portable or move it and i need to power it only with powerbank without any ither power suplly only with power bank with will be pluged-
Tell you what, I will have a word with some high power friends and see if they can change the laws of physics just for you because you need your project to be portable.
I'm curious as to why you're using an emitter follower to drive the LEDs?
Dwight
Did anyone look at the arduino uno schematic?
If you look at the usb power it is routed to the atmega16u2 via the F1 fuse link.
The UNO documentation states that the UNO is powered by the USB 5vdc or the 5vdc onboard regulator via the external power supplied (VIN) and is automatically selected.
Looking at the schematic I do not see where the USB power is in anyway used for anything but the ATMEGA16U2. Maybe the schematic is wrong.
Anyway... what I can see is All the +5vdc is supplied by the onboard regulator NCP1117ST50T36.
As the datasheet for the regulator specify's, you can get up to 1.5amps.
With VIN set to 9vdc and temperture 25c (77f) the specs are:
Min=1.00A Typ=1.5A Max=2.2A
The output current vs voltage diff specs this
With 9vdc in and 5vdc out there is a diff of 4vdc.
At 4vdc diff you can get 1.5A.
I've never used more than 800ma for the 5vdc pin and that is well within the range of the specs.
good luck
Almost two year old dead post revived.
mkjohnson1952:
If you look at the usb power it is routed to the atmega16u2 via the F1 fuse link.The UNO documentation states that the UNO is powered by the USB 5vdc or the 5vdc onboard regulator via the external power supplied (VIN) and is automatically selected.
Looking at the schematic I do not see where the USB power is in anyway used for anything but the ATMEGA16U2. Maybe the schematic is wrong.
Anyway... what I can see is All the +5vdc is supplied by the onboard regulator NCP1117ST50T36.As the datasheet for the regulator specify's, you can get up to 1.5amps.
With VIN set to 9vdc and temperture 25c (77f) the specs are:
Min=1.00A Typ=1.5A Max=2.2A
The output current vs voltage diff specs this
With 9vdc in and 5vdc out there is a diff of 4vdc.
At 4vdc diff you can get 1.5A.I've never used more than 800ma for the 5vdc pin and that is well within the range of the specs.
good luck
It's not.
Path is USB socket > Polyfuse F1 > Reverse polarity protection mosfet > 5volt rail.
True, if V-in is >6.6volt or DC socket is >7.3volt.
Look again.
Maybe you can get some of those specs if you submerge the Arduino in liquid nitrogen.
The practical limit for the 5volt rail with 9volt on V-in is ~250mA (that includes the 50mA for the Uno itself).
800mA is just one limit. That current can only be reached with 6.2volt on V-in because of the temp limit.
With e.g. 12volt on V-in, max available current drops to ~150mA (~100mA available for connected devices).
Leo..