Buck Converter vs Voltage Divider - Electrical Engineering Stack Exchange most recent 30 from electronics.stackexchange.com 2019-08-23T05:08:36Z https://electronics.stackexchange.com/feeds/question/333965 http://www.creativecommons.org/licenses/by-sa/3.0/rdf https://electronics.stackexchange.com/q/333965 1 Buck Converter vs Voltage Divider Shicon Wen https://electronics.stackexchange.com/users/160167 2017-10-11T22:15:15Z 2017-10-11T22:37:16Z <p>Why would I prefer to use a buck converter over a voltage divider, and vice-versa?</p> <p>I know that voltage dividers are less complex and cheaper than buck converters, given that voltage dividers are simply two resistors.</p> <p>What are other pros and cons of using a buck converter?</p> https://electronics.stackexchange.com/questions/333965/-/333967#333967 2 Answer by Simon B for Buck Converter vs Voltage Divider Simon B https://electronics.stackexchange.com/users/77938 2017-10-11T22:20:30Z 2017-10-11T22:20:30Z <p>It's generally down to efficiency. For very small currents, a voltage divider can use very little power (by using high value resistors_, while a buck converter will use power just powering itself.</p> <p>But at larger currents, a voltage divider can waste a lot of power as heat in the resistors. A buck converter might be ~80% efficient under load.</p> https://electronics.stackexchange.com/questions/333965/-/333969#333969 0 Answer by Big6 for Buck Converter vs Voltage Divider Big6 https://electronics.stackexchange.com/users/108065 2017-10-11T22:26:08Z 2017-10-11T22:37:16Z <p>Voltage dividers are not a good choice to source current to a load. If you draw significant current from it, then the voltage at the output of the divider drops.</p> <p><img src="https://i.stack.imgur.com/Nz0Cd.png" alt="schematic"></p> <p><sup><a href="/plugins/schematics?image=http%3a%2f%2fi.stack.imgur.com%2fNz0Cd.png">simulate this circuit</a> &ndash; Schematic created using <a href="https://www.circuitlab.com/" rel="nofollow">CircuitLab</a></sup></p> <p>As you change the load value, you change the value of \\$V_{out}\\$. If you want to keep the voltage pretty much constant, the current through the load should a lot smaller than the one through \\$R_2\\$.</p> <p>A dc-dc converter (buck, boost, etc) makes sure the voltage stays pretty much constant under different load conditions. If you find them to be too complex or an overkill for a specific application, you could instead choose an LDO.</p> <p>A voltage divider would find an application, for example, as an input to an ADC, because the ADC only needs to measure the voltage level to translate that into a binary number, while drawing little current and therefore does not disturb the output voltage.</p> https://electronics.stackexchange.com/questions/333965/-/333971#333971 0 Answer by Simon Richter for Buck Converter vs Voltage Divider Simon Richter https://electronics.stackexchange.com/users/3119 2017-10-11T22:33:21Z 2017-10-11T22:33:21Z <p>Keep in mind that voltage dividers have three legs, and the voltage in the junction is determined by all three.</p> <p>Normally, two of these are resistors with a known value with one side connected to a supply rail (= low resistance), so the combination of voltage and resistance is known and fixed for these. The third leg, the "output", however also affects the voltage, and in a normal voltage divider, you want a high resistance here to minimize the effect.</p> <p>If you have a high resistance on the output path, it is no longer usable as a supply rail, because that would need to be low resistance — try connecting a voltage divider behind a voltage divider.</p> <p>A typical buck converter contains a voltage divider on the feedback path to select the output voltage. The feedback input is a high-impedance comparator input, while the output of the buck converter is connected to a large capacitor that acts as a low-impedance source, so the output of the voltage divider is well-defined.</p>