USB Charging Adapters for Cars

I use a 10 ohms resistor and a 7805 to charge (250mA) my Android phone. The resistor drops a few volts to stop overheading the 7805. I could go switching, but why bother.

Sounds about right.

I also have a Garmin GPS I bought to survive NY ;-) The Q45 has that built-in, so I'll add the Garmin to the pick-em-up truck.

Wonder if anyone has manufactured a car-compatible USB hub ?:-) ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Look at Ipad accessories and stuff. I have a FM transmitter that has a USB socket in the lighter plug. Also my Razr has a mini USB that charges fine from one of those cheapie plugin lighter chargers. It has a small switcher and 5v out.

Cheers

Jim Thompson wrote in news: snipped-for-privacy@4ax.com:

I took apart an old 12V cellphone charger(not a USB type),and it had a Motorola 34000 series IC in the cig lighter plug,some 8-pin DIP switching regulator. I still have it around here somewhere(packrat),if I find it,I'll post the chip number.

USB outputs +5 V,IIRC. but you probably already knew that.....

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Jim Yanik
jyanik
at
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dot com

Almost certainly the MC34063. All the cig-lighter-5V-SMPS units I have seen use them.

If you have the "Dollar Tree" stores in your area, they sell cig lighter to USB adaptors for one dollar. Cant beat the price. Get one and take it apart.

n

=A0 =A0 =A0 ...Jim Thompson

g e

But there are still plenty of linear cig-ligher plugs. The IC is small, but the L and C are huge. We are still debating whether it make sense for 250mA.

Yes, it goes on the IGN tap. 1/4 A while the engine is running is no big deal.

What, like a plug-in hybrid? I don't think you're going to be able to charge one of those from a USB port ;)

Well, then charge it from the cigarette lighter.

Same car?

But of course! Renewable energy!

Algor says it can be done ;-) ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

I found this...

...Jim Thompson

-- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 | I love to cook with wine. Sometimes I even put it in the food.

Anything from a plain old linear 5V regulator to a fancy buck converter, LDO regulator combo. The latter probably isn't necessary if you only charge when the alternator is there to make up the losses.

There are some issues with 'handshaking' between some USB loads and chargers. Apple products are infamous for not charging off plain old 5V supplies.

There is some info in the Wikipedia article:

If your load works off a cig. lighter USB adapter, its probably not that finicky.

--
Paul Hovnanian     mailto:Paul@Hovnanian.com
------------------------------------------------------------------
668: The Neighbor of the Beast

Thanks, Paul! ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

=A0 =A0 ...Jim Thompson

LDO

has some info on charging apple stuff

for a a cigaret lighter USB adapter, its hard to beat tearing something like this apart:

5V/650mA $4.95

-Lasse

Anybody contemplating something like that oughta read this.

Don't skimp on the input protection. Bad things can happen when the regulator shorts.

When people ask me for this kind of advice, I always ask, "How much are you saving over buying a real regulator designed by the vendor for the device in question?" "How much to replace the fancy gizmo with the picture of fruit on it when your homemade supply smokes it?"

Chinese EBAY stuff is always crap and risky. You don't get adequate protection for 99-cents shipped from China.

Yes, homemade designs without adequate protection often work. Running blindfolded across the street often works too. Just a matter of how lucky you feel.