| BenBoost


This project is a boost converter that takes the input from a 3.7V Li-ion battery and outputs 5V through a USB port with a 1.5A peak output.

This tutorial is split into multiple sections: Introduction (this one), Schematic, PCB Design, and the final product. You can navigate to any of these sections through the links above.


For this project, I used:

- (1) TPS61235P

- (1) 41.2KΩ resistor
- (2) 1MΩ resistors

- (1) 10µF capacitor
- (2) 22µF capacitors
- (1) 10nF capacitor
- (1) 1µF capacitor

- (1) 1µH inductor

- (1) TPS2514A

- (1) 1µF capacitor

- (1) Female USB port

- (4) Pin Headers

- (1) 18650 lithium-ion battery


For this project, I decided to use the TPS61235P from Texas Instruments. This IC is a boost converter that takes a 2.3-5.5V input and outputs an internally-regulated 5.1V. With a very high efficiency, this chip will easily output a high enough current for my needs.

For the most part, I followed the typical application schematic located in the TPS61235P's datasheet, but read through the datasheet to find tune my current output and other values. Because of the problems I have had with this boost converter in the past, I used TI's simulation tool and formulas listed in the datasheet to get the circuit to work the way I wanted.

I also designed the circuit to implement the TPS2514A, also from Texas Instruments. This is a USB DCP controller, which is designed to supply a voltage to the D+ and D- pins of the USB port. I ended up not soldering this chip on the board, and instead shorting the D+ and D- pins on the USB port, as this method will allow up to a 1.5A output through the USB port, according to the USB standards.[1][2]

BenBoost schematic

PCB Design:

While designing the PCB, I placed the USB port on the board and tried to fit the components as close to one another as possible without making it too difficult to solder. This kept costs down, and allowed a smaller overall circuit footprint.

The green plane across the PCB is a ground plane that covers the entire bottom of the PCB. All vias that lead there connect ground to different components on the PCB.

BenBoost PCB design BenBoost PCB render

Final Product:

After soldering all of the components on the PCB, it works perfectly, with no apparent shorts or other problems. Since I don't need to use the TPS2514A, I can remove that footprint, compressing the rest of the components even closer together. I would like to use the extra space to put an LED indicator on the PCB allowing me to see if the board is working without having to use a multimeter. Overall, this design worked as I expected.

BenBoost final product