LM2596

[camilozk]

Hi!

I bought a LM2596 in ebay, and I was hoping to be able to use it as a "usb charger" connected to a 12v Lipo Battery


LM2596 - https://www.ebay.com/itm/10pcs-Mini...748379?hash=item3d5e66015b:g:VoYAAOSwo3tavZWc

Battery - https://www.ebay.com/itm/DC-12V-200...b5:m:mBohpJ0IHsOumaefM8SOyaQ&var=572664729205

Even though I can read 5V with my multimeter, some devices like my old iphone 3 and another iphone 6 are not being charged by the system. What is happening here?

thanks!

 

[davenn]

some devices like my old iphone 3 and another iphone 6 are not being charged by the system. What is happening here?

because an iPhone charger cable isn't a standard USB cable
It has resistors on the large USB plug end

do some googling on USB plug wiring for charging iphones

 

[AnalogKid]

Many switching regulators have a minimum load current requirement. For a 3 A part, it might want to see at least 300 mA of load current to form a stable output.

ak

 

[davenn]

Many switching regulators have a minimum load current requirement.

yeah but in this case he is reading 5V out

it's just the stupid iphone charging system that is messing with him

 

[camilozk]

because an iPhone charger cable isn't a standard USB cable
It has resistors on the large USB plug end

I am using iphone priginal cables, so I dont think the problem is in the cable.

Many switching regulators have a minimum load current requirement. For a 3 A part, it might want to see at least 300 mA of load current to form a stable output.

I found the datasheet of the LM2596, but I dont know how to read it. is that the case with this part?

 

[davenn]

I am using iphone priginal cables, so I dont think the problem is in the cable.

OK
The resistors may well be built into the USB connector.
Or because you are having problems, maybe it is just a plain cable and it is to be used with a charger that has the resistors built into its circuitry

is that the case with this part?

After a quick read, I don't see anything stating that in the datasheet

OK so I think it is time you showed us your construction sharp/clear photos
What is the DC into the reg circuit ? … maybe you have done something wrong ?

I don't really suspect that since you said you are getting 5V out of it ….
So I still think it is an iPhone cable/resistor issue


Dave

 

[camilozk]

I couldnt believe I make a mistake in this configuration

12v battery -> LM2596 -> usb connector

 

[Alec_t]

Well, that's a DC-DC converter, not just a LM2596. It has only V+ and V- rails going to the USB connector. Perhaps your iphones are looking for specific voltages on the D+ and D- pins of the connector?

 

[camilozk]

Well, that's a DC-DC converter, not just a LM2596. It has only V+ and V- rails going to the USB connector. Perhaps your iphones are looking for specific voltages on the D+ and D- pins of the connector?

Sorry, LM2596 is what the board says and I thought that was it.

Any suggestion?

 

[Harald Kapp]

It's a DC/DC converter based on an LM2596 chip.
The iphone needs a special charger or charge cable (cf. Dave's post #2). Probably the required resistors are not part of the cable but the original iphone charger, Easy to test with a multimeter by checking the cable (not being connected to the charger). You can add the resistors as required and charge current should go up as expected.

 

[camilozk]

But I am using original iphone cables with which I can charge the devices not only with an iphone charger, but also with cheap chinese usb charger, the usb from a computer, etc.

I wouldnt understand how a cheap chinese charger, or the usb from a computer works and the "charger" that I prepared doesnt, when the only thing all 3 devices do is provide voltage

 

[davenn]

I wouldnt understand how a cheap chinese charger, or the usb from a computer works and the "charger" that I prepared doesnt,

because as I have already stated, the resistors may be built into the charger

when the only thing all 3 devices do is provide voltage

when it comes to iphones, that is a false statement

 

[camilozk]

because as I have already stated, the resistors may be built into the charger

what I am saying is that I am usign very different chargers from very different sources. So why would a Computer´s USB, a chinese USB charger and other USB chargers have resistors that only a Iphone USB charger require?

when it comes to iphones, that is a false statement

How is it then. It would be useful to go forward with the discussion to not only provide statements, but also to argument about them

THANKS!

 

[davenn]

what I am saying is that I am usign very different chargers from very different sources. So why would a Computer´s USB, a chinese USB charger and other USB chargers have resistors that only a Iphone USB charger require?

How is it then. It would be useful to go forward with the discussion to not only provide statements, but also to argument about them

THANKS!

did you bother to read the link that Harald gave ??

I assume not by your response


you have been given all the info you need but you seem not to take it in and do some further research

 

[camilozk]

@Harald Kapp, Thank you very much for the link! I already adapted my circuit and it works perfectly with all my electronics devices. Thanks again

@davenn, Thank you very much for pointing out the link. As a matter of fact I havent seen there was a link there. It is a little bit sad that you seem to assume the worst about people. Perhaps you could try being more supportive, since I could expect that a lot of people (like me), whi search for support in this forum, not necessarily have a lot ok knowledge on electronics. Thank you very much in advance for your future patience towards other users in need.

 

[BobK]

Care to share with us how you adapted it?

Bob

 

[camilozk]

absolutely!

As explaines in the link (http://www.instructables.com/id/Modify-a-cheap-USB-charger-to-feed-an-iPod-iPhone/) I connected a 330ohm resistor between pin 1 and 2 from the usb connector, and a 220ohm resistor between pin 3 and 4, and I also connected pin 2 and 3 together. Pretty straight forward!

 

[BobK]

Yep, just like several posters were saying.

Bob

 

[camilozk]

isn´t that brilliant? exactly why we search answers in forums. lovely.-

 

[camilozk]

Now I have tested the system with an old iphone 3 and it works, and iphone 6 and it works, but the ipad is not charging. any idea?