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Difference between DC/DC converter and voltage regualtors for use in PCBs
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mike buba:
Hi,
what is the main difference and advantages/disadvantages of DC/DC converters and voltage regulators when used in PCB design?
I need to reduce voltage level from 15Vdc to 12Vdc, 2A and there are two options I am considering:
* Traco Power DC/DC converters, e.g. THL 25-1212, or
* Texas Instruments Voltage Regulators, e.g. LM1085-12Not looking into capacitor or resistor voltage dividers.
Apart from price, which is one order of magnitude higher for DC/DC converter, are there any other reasons to choose one over the other and vice-versa?
Kind regards
T3sl4co1l:
Well yeah, impedance dividers are out at DC. :) Resistor divider will work as well as a linear regulator if your load is a constant 12V 2A, but if it varies, definitely big nah.
(Unless you argue that an SMPS is an impedance divider, in which case, sure!)
Traco is a pricey brand, are you sure you haven't found anything else?
The biggest thing to watch out for in buck converters, is the dropout voltage. Some can go to 100% duty cycle, some cannot. Check the datasheet.
The SMPS has higher efficiency, whereas the linear reg drops (15) - (12) = 3V and dissipates up to (3V) * (2A) = 6W. With a 24W load, evidently an SMPS below 83% is worse than useless; but a proper one should be well over 90%, which saves on power consumption, heat dissipation, size and overall cost (don't forget the cost of the heatsink, hardware, and labor in assembling them all together).
Tim
Kirill V.:
The most important difference DC/DC converter and linear regulator is the ability to provide galvanic isolation at converter using.
There are converters without galvanic isolation and they are cheaper than TRACO. If you need to simple lower the voltage by a few volts without having to isolation you can look at them
MosherIV:
DC/DC converters are efficient, typically 80 to 90%.
However, they can be noisey. They work by converting DC to some kind of pulse hence the noise.
Voltage regulators burn off the excess voltage into heat.
They are very low noise.
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