How a DC-DC converter works

　・In Japanese
premise knowledge
　・Basics of electrical circuits
　・RC circuit
　・Electromagnetic induction

■What is a DC-DC converter?

A DC-DC converter is a device that has the ability to step up or step down direct current. It mainly consists of a transistor and a coil, and is a type of switching regulator.

＜Step-up DC-DC converter＞

as below.


Explain the operation. A transistor has the role of a switch, so the diagram is represented as a switch. When the switch is turned on, current flows as shown below.


When the switch is turned off in this state, the coil causes electromagnetic induction and a voltage is generated. When combined with the power supply voltage (if power supplies are connected in series, the voltage will be the sum), a high voltage will be generated. This is how boosting works. The capacitor is used to remove noise, and the diode is used to prevent the charge stored in the capacitor from flowing backwards.

＜Step-down DC-DC converter＞

The step-down type circuit is as follows. The individual roles of the coil, capacitor, and diode are the same as in a step-up DC-DC converter, but the overall function changes just by changing the circuit. When the switch is turned off, the coil momentarily generates a high electromotive force, but the average voltage drops. The difference from a step-up DC-DC converter is whether or not the voltage from the power supply is applied.

List of related articles TOP MENU Electrical/electronic circuit ・Freewheeling Diode ・Alternating current ・Termination resistor ・CPU, LSI, IC, ASIC ・Adders, Subtractors ・H-bridge circuit ・Motor type ・Inverter ・AC-DC converter ・DC-DC converter ・Transformer ・ROM, RAM, register, cash ・open/short circuit failures ・Low-side, high-side driver ・Mechanism of electric shock ・Zener diode ・Rectifier circuit ・Pull up/down resistor ・Joule heat ・Solenoid valves, relays ・Comparator