What Is a Boost (Step-Up) Converter?
A boost converter (step-up converter) is a DC-DC converter that raises the input voltage to a higher voltage. It's indispensable in circuits that want a high voltage from a single battery.
How Does It Work?
When the transistor turns on, the inductor stores energy from the input. When the transistor turns off, the inductor passes its stored energy to the output through a diode, stacked on top of the input voltage. So the output ends up higher than the input.
Why Does It Step Up?
The inductor's resistance to a sudden interruption of its current causes a voltage larger than the input to form across it; this carries the output upward.
| Property | Value |
|---|---|
| Function | Steps the voltage up |
| Efficiency | 80-95% |
| Output | Higher than input |
Where Is It Used?
Common in producing 5V from a 1.5V battery, LED backlight drivers, power banks, OLED panel supplies and wearables.
Why Is the Input Current High?
While a boost raises the output, power is roughly conserved: since the output voltage is higher than the input, the input current is markedly larger than the output current. So the conductor and source feeding the boost input must handle the high current; otherwise the input voltage sags and efficiency drops.
Common Mistakes
- Overload: as the current drawn from the boost rises, the input current rises much faster; the limit must not be exceeded.
- Diode choice: if a fast/Schottky diode isn't used, efficiency drops.
- Idle output: some boosts pass the input voltage to the output even when off.
Frequently Asked Questions
Can a boost lower the voltage?+
Why isn't efficiency 100%?+
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