Automotive input protection circuit ( ~ 22v ) [REQUEST]

Status
Not open for further replies.

andre_luis

Super Moderator
Staff member
Joined
Nov 7, 2006
Messages
9,642
Helped
1,191
Reputation
2,401
Reaction score
1,218
Trophy points
1,403
Location
Brazil
Activity points
55,928
Dear friends,


I´m working with an embbeedded system, designed to work in Trucks and Omnibus.
However, dependig on vehicle model, and maintenance status, a lot of power supplies ( 24v -> 12v ) are burned.
I know that´s because some voltage spikes appears at battery bus.

Could anybody give to me a sugestion to protect my power supply ?



Thanks a lot in advance.

+++
 

By knowing the architecture of a power supply’s you can adapt/change circuit for overvoltage protection. Any details about power supply?
 

An appropriate combination of TVS diodes or MOVs along with input filters should protect from any input transients. However you need to know what the transients are like and how often they occur to size the components appropriately.
 


Automotive wiring and grounding is often pretty poor and poorly maintained,
and accessory load-dump can make severe flyback spikes. I've seen up to
60V (on a 12V system) stated. If I were you I'd look for voltage regulators
or converters that are designed and rated for automotive, and use line
interface ICs that can tolerate volts of ground offset in either direction.

The low end can also be a problem, I've had inverters flicker at 10V when
plugged into a vehicle with a lousy alternator and had that take out a serial
port.

If you look at manufacturers who sell ICs into the OEM automotive market
you should fins a lot of primer material about the electrical environment.
 

Don't overlook that static charge is known to accumulate on vehicles. Strong enough voltage to spark fires at gas pumps (documented).

Might be a problem if the charge builds up unequally inside your circuitry, particularly across insulated gate devices. It may perforate them.

As to prevention, I don't know for certain but I suspect commercial manufacturers install back-to-back zener diodes (or varistors, surge absorbers, etc.) in lots of strategic spots.

Another source of high voltage spikes can come from the solenoid. I've seen them chatter when a low battery is trying to turn over the engine. The sudden on and off switching causes the spikes. When touching one I could feel shocks just like house AC going through my hand.
 

hi,
Please go through the below link...it explains both primary and secondary protection of the power line inputs from load bumps and other transients occuring in an automotive environment...

https://www.vishay.com/docs/88490/tvs.pdf
**broken link removed**
 
Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…