In need of a 3.3 volt regulator can handle at least 300 mA. Can take an automotive voltage as an input. What would you recommend?

[edit] This will be in a poorly vented area so heat will become a factor. I'm thinking of a 3.3 volt regulator, but am open to other ideas as well, such as PWM regulation; but am not so sure if PWM will maintain the voltage at 3.3 volts while the automotive voltages swing from 12.6 to 14.6 volts (engine off to full recharging of the car battery).

 

Hello,

When you want to use a linear regulator, have a look at the LT1086.
When you want to go for a switching regulator, have a look at the LTC7103.

Bertus

 

From 14 to 3.3V, at 300mA you're going to be dissipating more than 3W in a linear regulator, that's going to get really hot without circulation and maybe a heatsink. You might look into a buck solution which will be more efficient (less heat). You can get everything on one module, maybe something like this:

https://www.mouser.com/ProductDetai...9lZSPl3RQsOIly2NLEkKhLg7MmKe%2b5c493qllSznQ==

 

@MrSoftware Looks good, and yes, heat will be a concern. Even with a heatsink, I still don't know about dissipating much heat; especially in the summer time when inside the car can be quite warm. I'm leaning toward @bertus solution using the LTC7103.

This year I attended a train expo in Milwaukee. Pretty interesting. I'm contemplating building a train power supply (not the same project as what's going in the car). I've seen controllers that apply power gradually and simulate the natural acceleration of a train. Power supplies are not my wheelhouse. There is much opportunity for learning in this regard. But the train power supply will be my next project - after I finish the car project and finish building the marble machine for my grand children.

 

In need of a 3.3 volt regulator can handle at least 300 mA. Can take an automotive voltage as an input. What would you recommend?

[edit] This will be in a poorly vented area so heat will become a factor. I'm thinking of a 3.3 volt regulator, but am open to other ideas as well, such as PWM regulation; but am not so sure if PWM will maintain the voltage at 3.3 volts while the automotive voltages swing from 12.6 to 14.6 volts (engine off to full recharging of the car battery).

I am for LM2576, I have tested it on a smart AGV and it works fine even without a heat sink for 300mA. Plus it takes the voltage from a "12VDC" battery. But don't pick the small smd package.

 

In need of a 3.3 volt regulator can handle at least 300 mA. Can take an automotive voltage as an input. What would you recommend?

[edit] This will be in a poorly vented area so heat will become a factor. I'm thinking of a 3.3 volt regulator, but am open to other ideas as well, such as PWM regulation; but am not so sure if PWM will maintain the voltage at 3.3 volts while the automotive voltages swing from 12.6 to 14.6 volts (engine off to full recharging of the car battery).

You could consider a shunt regulator that would fail safe in the noisy automotive environment - as opposed to a normal linear that dumps the full 12V into the load when it breaks down.

Or you could concentrate on transient protection devices. Automotive types tend to come in at about 68V - so you might still spend a while leafing through data sheets for a linear reg chip that can handle what's left.

There are probably off the shelf switcher modules - but check they match the tranzorbs you can get hold of.

 

There's nothing wrong with parts like the LTC7103 or the LM2576, but know that they are just the controllers, you need to add your own inductor and handful of other parts to make it work. Check the data sheets for a schematic called something like "Typical Application". From my own (limited) experience with switching power supply circuits, when you get a noise or some other odd issues, troubleshooting is not always strait forward. Things like trace length, loops in your traces, how close traces run to specific parts, etc.. can make a big difference. If you buy a complete module, all of this has already been worked out for you.

 

There's nothing wrong with parts like the LTC7103 or the LM2576, but know that they are just the controllers, you need to add your own inductor and handful of other parts to make it work. Check the data sheets for a schematic called something like "Typical Application". From my own (limited) experience with switching power supply circuits, when you get a noise or some other odd issues, troubleshooting is not always strait forward. Things like trace length, loops in your traces, how close traces run to specific parts, etc.. can make a big difference. If you buy a complete module, all of this has already been worked out for you.

Switchers are fine - but step down usually means buck with the same punch through danger as a linear.

A flyback with step down transformer just stops dead if the switch semiconductor fails.