usb charger with lm7805

I built a super simple circuit to take any voltage down to 5v from any Vin, but now 'n hooked it to a USB port, pluged my ipod in. no magic smoke, since I checked it with my multimeter, but the ipod is also not showing a charging symbol like it would if I charged it with a computer. Is this bad?
Theoretically any USB gives out 5V, so I figured it will work.

The USB gives 5V, the lm7805 has a dropout of about .7V. This means you need to put in above 5.7V or it will not work.

Just adding something I have seen pop up in walgreens just the past few months.. Tiny USB chargers for cig lighter or 110 outlet... 9.99 and they are tiny

Thanks for the reply. The dropout voltage is really not a problem, all I want to know is if the device will work if I power only the 5V rail of the female usb port, and do nothing to the data rails.
Please see the link for a better understanding of what I'm trying to say
Thanks

LINK:https://pinouts.ru/Slots/USB_pinout.shtml

I'll let somebody else answer this hazardous question

hannobisschoff@gmail.com said:

now 'n hooked it to a USB port

Click to expand...

That gives the impression that you are connecting it to a computer.

I suspect that you are trying to charge your iPod with it, from some other power supply.
Could you clarify?

OH, sorry about that poor choice of words. Yes, I want to use another input (higher than the dropout voltage) to charge my iPod.
Would it damage the device?

birdman0_o said:

The USB gives 5V, the lm7805 has a dropout of about .7V. This means you need to put in above 5.7V or it will not work.

Click to expand...

I thought an LM7805 needed at least 7 volts to operate? But hey, if you know of a version that only needs .7 volts above Vin, and comes in a TO-220 case - I'd love to hear about it...

As drawn the original drawing should work fine.

USB pin assignment as follows :

Pin 1 -- VCC (5 VDC)
Pin 2 -- D- (Data -) typical cable color is White
Pin 3 -- D+ (Data +) typical cable color is Green
Pin 4 -- GND (Ground)

Just make sure you get the pinout correct. The data lines are ignored. This is true for charging most USB devices with the exception of a few.

As to dropout voltage on a side note. Any standard LM78XX device (regulator) I am familiar with has a 2 volt dropout voltage. Therefore in the case of a LM7805 the input voltage must be a minimum of 7 or more volts.

As to low dropout versions there are chips like the LM3940 low dropout regulator in a TO 220 case and good for about an amp and the LP2954/LP2954A low dropout regulators good for only about 250 mA but in a TO-220 case.

That's My Take
Ron

You need some load on the data pins for an ipod to charge. Look in Google for the circuit.

EDIT: One link says this: "The Data+ and Data- lines need to be held at a certain voltage for the phone to recognize that it should charge. The Data+ pin needs to be held at 2.8 volts, the Data- pin needs to be held at 2.0 volts."