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supply voltage obtaining (4.2V,3A) from 12V car battery

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yassin.kraouch

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supply voltage

i would like to obtain (4.2 V, 3 A) from a car battery which deliver 12 V, how can i obtain this??
regards,
 

supply voltage

euhh but this regulator can only deliver 1 A i need 3 A in output!!
 

Re: supply voltage

yassin.kraouch,
You could use a linear regulator, such as the LM317, with an external pass transistor. See the app notes for the LM317 at **broken link removed**.
However, keep in mind the power (23.4 Watts) that the pass transistor must dissipate. You would need a fairly large heat sink to keep the chip temperature of the pass transistor less than 150 deg C. A more efficient solution would be a buck switching regulator. You can find lots of reference designs for this type regulator on the web.
Regards,
Kral
 

Re: supply voltage

Here is a boost regulator circuit using LM317. You may use this circuit to get the 4.2Volts, 3A. Adjust the variable resistor to get the required volatge at the output. Hope it helps you. Do not forget the "helped me" button. Good luck.
 
Re: supply voltage

Ld29300 CAN ALSO BE USED
 

supply voltage

An LM350 is an adjustable 3A regulator.
An LM338 is an adjustable 5A regulator.

They both reduce the current if they get too hot then shutdown.
 

Re: supply voltage

Has anyone offered up a switching regulator?
like LM2670 or A8447 or mic4685 ((I use the LM2676))
**broken link removed**
**broken link removed**
**broken link removed**
That way he could drop the 12V down to 4.2 without dumping it as heat.
Its nice when things don't get too hot to touch.
 

supply voltage

ok thank you all, but a special thank to pranam77!!!! :)
 

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