automotive powersupply - Page 1
Forum section: electronics / projects

author: shyjuvm
author_rank: Newbie
timestamp: November 03, 2012, 10:15:56 am
content: Can any one suggest me a strong power supply for automotive ( its worst condition three wheeler)input 6V to 32 Vout put 5 V @500 mATransient / load dump protection up to 120 VOver current protectionNoise filteringRegardsshyju

author: Simon
author_rank: Unknown
timestamp: November 03, 2012, 10:22:53 am
content: why do you want such a large input range ? many regulators don't go over 30V and you should never get near this anyhow, You could put a zener in series with the reg to help up the input limit but you must use some sort of protection against power spikes like a mov or TVS

author: Rerouter
author_rank: Super Contributor
timestamp: November 03, 2012, 11:38:27 am
content: 32V covers the maximum likely voltage for a 24V lead acid system, and almost all 12/24V chargers will use this range,as for the actual chip, there are a few little tips i can give in what you feed it, have a zener clamp across the input, say a 35V 1W or larger one, for positive spikes,now because you want 500mA i would probably recomend a switchmode otherwise you will be burning a whole heap of heat, it also fixes the output noise issue in that high frequencies are much easier to filter,i commonly use these chips in vehichles is one of these (for older bi-metallic gauges, full current rating barely gives off any heat)http://www.digikey.com.au/product-detail/en/R-785.0-0.5/945-1037-ND/2256217so far i have never seen one come back, though yes they are pricy and come a little short of your desired range, but they last

author: Simon
author_rank: Unknown
timestamp: November 03, 2012, 11:42:43 am
content: 24V systems generally won't see more than 28V (we do military stuff rated for 28V) so you will want a TVS diode that kills off power spikes nicesly but you need a 33V one to ensure the stand off voltage is high enough to no pass current at normal input voltages and the top clamping voltage of said TVS is 47V (probably depends on power of spike) so really you want 50V input. I've got a 30V reg with a 12V zenner in series to drop 12V and give an effective input of 42V, I've put a resistor in series creating a low pass filter with the reg input cap so hopefully slow down any spikes.

author: G7PSK
author_rank: Super Contributor
timestamp: November 04, 2012, 04:41:24 pm
content: One of these will do the trick. i got one and st it to 5 volts and put it in a box with a usb socket one end and a power jack the other end I can charge usb items from 3 volts to 28 volts input.http://www.ebay.co.uk/itm/320894112976?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

author: brainwash
author_rank: Frequent Contributor
timestamp: November 06, 2012, 10:18:34 pm
content: I think I actually understand the requirements because I was designing such a similar system myself: it's a three-phase magnet-generator type thing used on dirt bikes and snowmobiles. Dirt bikes to not have batteries and starters and just feed the raw voltage into the bulbs or whatever electrical thing is still installed on the bike. Bulbs (or lamps) also don't need regulation, they run fine on AC.Simplest way to do this: input the zener limited system voltage into an MC3423 (or similar), drive a few SCRs on the output.