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Is Automobile Power Viable for Electronics Projects?

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MatteP
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Joined: Fri Dec 09, 2016 10:36 pm

Is Automobile Power Viable for Electronics Projects?

Postby MatteP » Fri Dec 09, 2016 11:49 pm

I have some project ideas that would be targetted for use in a vehicle. I would like to consider the possibility of tapping into the car's 12V battery to power the projects, for example through the cigarette lighter port. I would put the input power from that port through a linear or switching regulator (e.g. a 7805 or similar), to give me 5V power. Am I likely to face any challenges in that approach? Are there front-end circuits that are a 'must have' for consuming automotive battery power in low voltage / low current embedded applications? Specific circuits and/or part recommendations are encouraged.
Then I found some protection against automotive power supply hazards.
I'm looking for a way to protect a small circuit which is to be used inside of a car or truck (12V or 24V power system). The circuit consumes about 12-15W. I use an isolated DC/DC converter module which can regulate 9-36V down to 3.3V.

I'm looking for recommended circuits or a controller IC that can take care of the usual hazards:

Load Dump Spikes
Reverse Voltage
OV/UV Protection
General noise on the power lines.
... Anything I might have missed.
Currently I have my eye on the LTC4365 http://cds.linear.com/docs/en/datasheet/4365fa.pdf from Linear Technologies. I've thought about using it together with a bi-directional TVS, clamping the voltage to 32V and protecting everything with a fast blowing fuse.

Would this be a proper solution or did I miss something here?

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SteveC0625
Posts: 446
Joined: Sat Jan 01, 2011 9:46 am
What radios do you own?: CDM's, CP's, CM's, and more

Re: Is Automobile Power Viable for Electronics Projects?

Postby SteveC0625 » Sat Dec 10, 2016 9:09 am

MatteP wrote:I have some project ideas that would be targetted for use in a vehicle. I would like to consider the possibility of tapping into the car's 12V battery to power the projects, for example through the cigarette lighter port. I would put the input power from that port through a linear or switching regulator (e.g. a 7805 or similar), to give me 5V power. Am I likely to face any challenges in that approach? Are there front-end circuits that are a 'must have' for consuming automotive battery power in low voltage / low current embedded applications? Specific circuits and/or part recommendations are encouraged.
Then I found some protection against automotive power supply hazards.
I'm looking for a way to protect a small circuit which is to be used inside of a car or truck (12V or 24V power system). The circuit consumes about 12-15W. I use an isolated DC/DC converter module which can regulate 9-36V down to 3.3V.

I'm looking for recommended circuits or a controller IC that can take care of the usual hazards:

Load Dump Spikes
Reverse Voltage
OV/UV Protection
General noise on the power lines.
... Anything I might have missed.
Currently I have my eye on the LTC4365 http://cds.linear.com/docs/en/datasheet/4365fa.pdf from Linear Technologies. I've thought about using it together with a bi-directional TVS, clamping the voltage to 32V and protecting everything with a fast blowing fuse.

Would this be a proper solution or did I miss something here?

If you are just trying to produce USB level power, why not just get one of these guys and be done with it?
https://www.bluesea.com/products/1016/D ... ger_Socket

Blue Sea marine electrical products are some of the best quality available. I have no connection to them other than I've used their products several times in different applications.

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jackhackett
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Joined: Tue Jun 10, 2003 8:52 am

Re: Is Automobile Power Viable for Electronics Projects?

Postby jackhackett » Sat Dec 10, 2016 6:53 pm

You don't want to use a bi-directional TVS in this application, it won't clamp reverse polarity until it reaches it's breakdown voltage.

For example, a 15V uni-directional between +12V and ground would clamp positive surges to 15V, and reverse voltage to something like -0.6V (diode forward voltage drop).
A bi-directional is two diodes back to back, so it clamps to the breakdown voltage of one diode, plus the voltage drop across the other. If the diodes are 15V you'd clamp at 15.6V for positive surges and -15.6V for negative. With that you could hook up power backwards and you'd get basically no protection against the reverse 12V.


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