Boost Converter (Step-Up DC-DC)
Step-up switching converters when you need more voltage than your input rail provides.
What is it?
A boost converter steps a lower input voltage up to a higher output. Storage inductor on the input, switching transistor to ground, freewheel diode (or sync FET) to the output cap. Used wherever the available rail is below what the load needs, e.g., single-cell battery driving a 12 V backlight, or USB 5 V driving a 24 V industrial sensor.
When do you need it?
- Single Li-ion cell (3.0-4.2 V) up to 5 V or higher.
- LED backlight or string driver (current-mode boost).
- USB-powered devices needing >5 V internal rail.
- Solar / energy-harvesting front-ends boosting from a low PV voltage.
- Audio amplifier rails (single-supply battery up to ±15 V).
How to pick the right one
- VIN range
- Must include your worst-case minimum (e.g., 2.7 V for a discharging Li-ion).
- VOUT (max)
- Has practical upper limit, boost duty cycle approaches 100% as Vout/Vin grows. Above ~5× ratio, consider SEPIC or flyback instead.
- IOUT
- Critical: average inductor current is much higher than output current (IL = IOUT × VOUT/VIN). Make sure the switch can handle it.
- fSW
- 500 kHz-2 MHz typical. Higher = smaller passives.
- Output type
- Constant voltage (most common) or constant current (LED drivers).
What Magnias offers
Two synchronous boost converters: MI5134K-TS (0.9 V start-up, 0.75-5.5 V input after start-up, output up to 5.5 V, 100 mA at 3.3 V from a single cell, TSOT23-6L) for one- to three-cell alkaline / NiMH or single-cell Li-ion products, and MI1815A-F32 (2-18 V input, 4.5-18 V output, 15 A peak switch current limit, AQFN3.0x2.5-11L) for SSD, LCD source-driver and microcontroller rails.