What Is a DC-DC Converter?
A DC-DC converter is a switching power circuit that changes one direct-current (DC) voltage into a different DC voltage with high efficiency. It produces far less heat than a linear regulator.
How Does It Work?
An internal transistor switches on and off very fast (PWM). Energy is stored and transferred in an inductor and a capacitor; the output voltage is set by changing the on/off ratio. Because energy is stored and passed on rather than turned into heat, the efficiency reaches 85-95%.
Basic Types
| Type | Function |
|---|---|
| Buck | Steps the voltage down |
| Boost | Steps the voltage up |
| Buck-Boost | Steps down or up |
Advantage Over a Linear Regulator
Unlike an LDO, which turns the excess energy into heat, a DC-DC provides high efficiency by transferring energy; that means long battery life and little cooling.
Where Is It Used?
Phone and laptop power stages, USB power banks, vehicle electronics, LED drivers and almost every high-current digital system.
Switching Frequency
The switching frequency sets how many times per second the converter switches. A high frequency allows smaller inductors and capacitors but increases switching losses; in design a balance is struck between size and efficiency.
Common Mistakes
- Wrong inductor: an inductor that saturates lowers efficiency and heats up.
- Poor layout: switching noise couples into the circuit if the PCB layout is bad.
- Noise-sensitive load: in a sensitive analog circuit a cleanup LDO stage should be added at the output.
Frequently Asked Questions
Is it the same as an SMPS?+
Why is there an inductor?+
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