I am a novice with building my own PCB, so I could use some help.
We are building a little PCB to take care of power supply to an edge device which does ML on road conditions.
The vehicles being fitted range from normal cars with 12V batteries to trucks with 24V batteries.
The PCB circuit and power supply of the edge devices requires 12V, so I need to curtail the voltage at this level, regardless of the input.
What is the difference between the following, and which would be most suitable for my application?
DC to DC controllers will definitely not be it (generally just a MOSFET as a power switch) DC to DC converters will generally be a whole module to do it all which probably would not be suitable for PCB use, DC to DC switching regulators will just be the regulator so you will whatever the datasheet says so probably an inductor to produce the switching frequency, some filtering and reverse polarity protection if needed.
Hello dirk.neethling, welcome to the TechForum!
These devices all perform the same basic function, which is to convert one DC voltage to another DC voltage. As joshuacook535 mentioned above, the differences are in what components are in each IC.
Regulators are basically just converters without the inductor in them.
Controllers tend to get a bit more complicated as they rely on other components externally from the chip to perform the conversion of the voltages, however they also can hand a bit more current as there are more components to share that current with.
As for which of these items best suits your application here, it really depends on how much you want to work with. For a simple option, I’d go with a regulator and an inductor or just a converter. The controller is a bit more complicated, so I don’t know if that would be the best option here.
Hi dirk.neethling,
Welcome to the Tech Forum!
The three categories you mention differ by level of integration.
Least integration - DC-DC Controllers
These are integrated circuits which only contain the controlling functions of the circuit. They require external switches (typically MOSFETs) as well as inductor(s), capacitors, resistors, and sometimes external MOSFET drivers. These are the most complex to design, but allow for the most flexibility in terms of output power and topology options. Proper layout is critical to get optimal (or even functional) performance.
Some integration - DC-DC Switching Regulators
These are integrated circuits which integrate both the controller portion and the power switching portion of the circuit (MOSFETs or BJTs) into a single chip. These will require an inductor (with the exception of charge-pump (switched-capacitor) topologies), resistors, and capacitors to complete the circuit. Proper layout is very important for optimal performance. These are typically the least expensive for a given set of electrical requirements.
Most integration - DC-DC Converters
These are modules which contain nearly all components required to perform the voltage conversion. The only other components they often require are external capacitors, resistors for setting output voltage (for adjustable output voltage version), and sometimes a filter to pass certain EMI standards. These come in both board-mount and external (off-board) versions and many offer galvanic isolation between input and output. These are generally the simplest and quickest to design in, but are usually the most expensive options for a given set of electrical requirements.
If you are only producing a small number of circuits, DC-DC converter modules may well be the best solution, as the time required for design-in is significantly reduced compared to the alternatives, and likelihood of doing it right the first time is also must greater. Also of consideration is that isolated DC-DC converters make it easier to get an output voltage that may be below or above the input voltage. In your case, the 12V output may be above the input at times.
Of special consideration in your design is the actual voltage range the device might see in circuit. Automotive voltages fluctuate significantly, so that full range needs to be accounted for. Additionally, automotive power rails can spike significantly higher than the nominal value during “load dump” incidents, so if one wants to design a reliable system, then the circuit should account for this either by designing in a regulator that can inherently handle this, or by adding protective devices to limit the exposure of the regulator to these events.
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Thanks, these are great answers, also those of Nate and Joshua. I think I will go for a DC-DC converter then. We are aiming for 12-24V batteries, but I obviously need to make sure to catch the voltage and current spikes coming from the vehicle.
With automotive power supplies intended for both 12 and 24V systems, it’s customary to have a continuous allowed operating input voltage of 10 to 30 VDC (about +/-20%).
I would consider that a bare minimum range, as voltages can really dip when starting in cold weather (like up here in northern Minnesota), and load dump can cause voltage peaks in excess of 60V for hundreds of milliseconds.
Here’s a list of good articles offering solutions to load-dump from several of our semiconductor manufacturers.
- Texas Instruments: Load Dump and Cranking Protection for Automotive
Backlight LED Power Supply - Maxim (now part of Analog Devices): LOAD-DUMP PROTECTION FOR 24V AUTOMOTIVE APPLICATIONS
- Monolithic Power Systems: From Cold Crank to Load Dump: A Primer on Automotive Transients
Me too, it’s the kind of range I’d only use for a low cost car/truck accessory or hobby project.
Nice set of reference article links thanks.
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