Comparing Voltage Boosting Circuits

Summary

Overview & disclaimers This post compares the power efficiency of some voltage boosting circuits. The circuits discussed here are: Buck converter Parallel buck converter Serial buck converter Pulsed transformer Joule thief Honorary mentions What we’re doing here is neither complete nor scientific and aspires to more than it delivers. Comparison base line The generic version of all voltage-boosting circuits in this comparisson is this: Generic voltage booster circuit We’ll require that all circuits lift a 5V DC input voltage to a stable 10V output voltage measured on a 1ΚΩ resistor load. Power efficiency is the power consumed on the resistor load divided by the power delivered by the input voltage source. All numbers were chosen semi-arbitrarily. 5V is a widely used voltage in low-power electronics, so it’s widely available and low enough to justify needs to raise a voltage for further use. We could have chosen eg. 3V or 1,5V, but some circuits don’t operate on such low input voltages, which would have reduced the selection to a uselessly small sample. The resistor load is important, because without load there is no power consumption and we couldn’t compare efficiencies. Also we want the circuits to prove that they can do something with the voltage they produce. 1KΩ is a representative resistance when driving CMOS logic, but too high for more complex circuits or even electric motors or larger LED installations. The efficiency numbers aren’t based on calculations or research – I merely ran each circuit in the excellent Lush Projects simulator [SIM] and recorded the numbers it gave me. We’re assuming that the control logic’s (eg. clocks, logic gates) power consumption is negligible. Thus the efficiency is calculated as the ratio of the power lost on the 1ΚΩ load resistor divided by the power generated by the power source. Both values were read from the simulator. Each power source includes a 1Ω resistor to model internal battery resistance, wire losses etc. Each circui...