The boost converter is a DC-DC converter used to create an output voltage that is higher than the input voltage. Boost converters are also used to drive LEDs placed in series in products like LED flashlights. The boost converter suffers from vulnerability to a short circuit load. This paper discusses why boost converters are vulnerable to short circuits, ways to protect a boost converter from short circuit, and alternative power electronics converters that don’t have a short circuit vulnerability that can be used in place of the boost converter.

### Intro to the Boost Converter

As previously stated, a boost converter produces an output voltage that is higher than the input voltage. Examples of boost converters include the following:

• Producing 5V charging ports in a lithium battery pack
• Producing power rails in a smartphone.
• Driving LEDs in series in an LED lantern or flashlight.
• A voltage regulator in an Arduino-based project.
• Creating a high voltage to run a motor from a single cell lithium battery.

### Protection with a Load Switch

A load switch is power MOSFET with additional circuitry integrated. Additional features may include a charge pump and level shifter to bias the MOSFET gate and also overcurrent protection features that shut the switch off if current is excessive. Using a load switch has the following advantages over using a MOSFET:

• Reduces BOM count
• Reduces PCB footprint
• Reduces the complexity of design, as you don’t have to add additional control circuitry.

### Boost Converter Controllers with Built-in Protection

Practical boost converters are controlled by an integrated circuit that regulates power conversion. Some of these boost converter controller circuits have built-in protection mechanisms such as load switches. Using a controller with built-in protection simplifies design, reduces BOM count, and reduces PCB footprint. Examples of boost converter IC’s that include protection features are Texas Instruments’ LM4510 and TPS61080.

### Protection with Fuse

A fuse can be placed on the input or output of a boost converter to protect against short circuit load conditions. See figure 6 for an example of how this is done.

##### Figure 6: Protection with Fuses on Input or Output of Boost Converter. Note that load switches and MOSFET protection circuits can also be placed between the boost converter output and the load, as is pictured with the fuse protection circuits.

The author recommends using the other approaches outlined in this article because the design with a fuse is more troublesome. If a short circuit condition occurs, the fuse will blow and have to be replaced. Circuits built with extra protection MOSFETs, load switches, or integrated protection will not require any components to be replaced if the converters work properly. These designs will save the end user the time and money of replacing burned fuses.  Additionally, fuses do not trip as quickly as one would expect from reading the datasheet. This can result in components and traces being burned up before the fuse blows. Designs using MOSFETs, load switches, and ICs with integrated protection can disconnect from loads in microseconds or faster, providing extra safety and robustness for the circuit. However, the fuse solution may be the simplest and cheapest to implement.

### Conclusion

The boost converter is used everywhere but suffers from vulnerability to short circuit loads. This paper has discussed several approaches to getting around this vulnerability including using MOSFETs, load switches, ICs with built-in protection, and fuses to disconnect the power converter in the event of a short circuit condition.