LiPo Power Board is a power manager for your battery-powered product. Since the breakout format, it is intended for prototyping and development. It is designed for a single cell LiPo battery (3.7V) and to supply 2 voltages: a fixed 3.3V and a secondary adjustable output, able to deliver higher voltage and current. A physical switch allows you to cut out the voltage on both channels. USB-C and Jack connectors allow to recharge the battery.
The boost part is very flexible since you can just change the ratio between 2 resistors to change the voltage output. Moreover you can copy and paste it to get a third voltage output.
A typical application in which this board finds a perfect suit is where the MCU runs at 3.3V and sensors and actuators (such as LEDs WS2812B) requires higher and stable voltage.
leakage current < 2uA (when OFF)
quiescent current < 800uA
maximum current on 3.3V channel: 500mA* (input 3.45V)
minimum current on 5V: 500mA (input 3.45V)
5V output adjustable
maximum charge current 1A (default: 800mA)
voltage will drop to 3V
This circuit is designed to work with a battery always connected. For developing purpose, you may need to detach the battery. In this case, you may activate the LDO mode (available through USB-C only), shorting SEL2 and opening SEL1. Otherwise, in the default configuration (with battery) keep SEL2 open and SEL1 don't care.
R1 value regulates the maximum current to recharge the battery, according to the formula I(mA) = 1/R1(kΩ). Moreover, this resistor controls the termination charge. In particular, when the charge current falls below a minimum current threshold, the recharge process ends. The recharge threshold is a percentage of the maximum current established by the manufacturer. In general, when the maximum current is high, the threshold increases its value, leading to a lower recharge level. Hence, if you need to use all the available capacity, lower the maximum current. However, the default configuration will work for the majority of the cases (my experimental setup with max current 800mA and battery 400mAh, stops at 4.1V), so if you are not sure about what you are doing, ignore this note.
The list of the pins and their functionality:
|3.3V||Regulated output at 3.3V|
|VBAT||Unregulated battery voltage|
|5V||Regulated output at 5V (adjustable)|
|PWR||Output HIGH after 200us the 3.3V is stable, otherwise grounded|
|SON||Set HIGH to activate the voltage regulators, LOW to turn off them. It is an alternative to the physical switch|
Each printed board has a version. Version advancements are ruled accordingly to Semantic Versioning.
To show the status of each version I use the following symbols:
|7||Just a couple of 2.54-spaced pins||EXT_BTN,SEL1,SEL2||1X02 2.54MM HOLES HEADERS PINS||3|