High-efficiency lipo to 3.3V/5V converter

A useful way to get 3.3V and 5V out of a lipo

A lot of times, you find your electronic project in need for power, more power and ultimately a lipo. Lipos can store a lot of energy, but their voltage range varies from 4.3-ish volts to 2.8V-ish. The voltage close to the max and min fluctuates a lot. Hence, many micro-controllers like the ESP32 rely on 3.3V while others like the Arduino require 5V and therefore have difficulties being powered by a lipo alone due to either over-voltage or under-voltage.

I wanted to design this because I needed a highly-efficient way to power 5V and 3.3V for an extended battery life and the ones I tried were not efficient enough. Many cheaper liner regulators or cheaper boost-converters have poor efficiencies (60-70% at max) and a very bad efficiency (around 10-30%) at lighter loads, not making them very suitable for applications where you need to maximise battery life.

As many electronic projects don't need to run 24/7, battery life is dependent on the power draw of the setup + all peripherals attached. in many cases, the deepsleep consumption of the setup influences the battery life more than the actual working consumption, hence it's critical to minimise this consumption as far as possible. With this module, the efficiency is fairly high at both high-loads (max. 400mA) as well as low-loads of a few uA, making this an ideal choice when you need to maximise battery life. With the design completed, it was now time to order the pcb.

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TPS63900 buck-boost converter

This small breakout board based on the TPS63900 IC makes it a breeze to convert the voltage from a lipo to 3.3V or 5V from an input range from as low as 1.8V and as high as 5.5V at significant efficiency even at ultra-light-loads, hence very little energy is wasted in the form of heat.

Although the max. current is limited to 400mA, it comes at an incredible IQ (quiescent current) of only 75nA, making it suitable for devices which depend on deep-sleep, such as the ESP32.

With an input range from 1.8 to 5.5V, this is perfect for a lipo, though there are several other battery chemistries which can work with this. Note that this is not a lipo-charger, only a highly efficient buck-boost converter. Switching between 3.3V and 5V is easy thanks to the slide switch. The other switch disables the IC.

With it's 4 mounting holes having a 2.5mm hole diameter, it can be easily integrated into 3d-prints or mounted easily via screws. Size: 25x25cmm with a height of less than 5mm. Did I mention this is breadboard friendly? All used components and the pcb itself are ROHS certified.

There's a total of 4 pins on this, VIN for the input voltage (+), VOUT for the output voltage (+) and two ground pins.

Features

• small size (25x25mm)
• high-efficiency (90%+) at both low-loads (10uA) and high-loads (up to 400mA)
• select output voltage without soldering through switches
• input voltage range from 1.8V to 5.5V
• includes on/off switch
• breadboard-friendly
• 4x mounting holes with 2.5mm diameter
• slim (5mm total height)
• no soldering required

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