Introduction

The LiPo Power Board functions as a power controller for devices powered by batteries, mainly aimed at prototyping use due to its breakout-style design. It operates with a single 3.7V LiPo cell and delivers two voltage outputs: a stable 3.3V and another adjustable output that can supply higher voltage and current levels. A built-in switch enables users to turn off power to both outputs when needed. The board supports battery charging through USB-C and DC jack connectors.

One of its key advantages is the flexible boost converter section, where the output voltage can be easily modified by adjusting the ratio of two resistors. This design also allows duplication of the boost circuit to create additional voltage outputs if required.This board is particularly useful in applications where a microcontroller operates at 3.3V while other components, such as sensors or devices like WS2812B LEDs, require a higher and more stable voltage supply.

For Full Project:

https://electronicsworkshops.com/power-management-board-for-battery-powered-projects/

Features

Low leakage current design for improved battery efficiency

3.81mm pin spacing for easy integration and compatibility

Includes 3D model support for accurate design and enclosure planning

Minimum guaranteed output current at 5V: over 400mA (tested at 3.3V input)

Circuit Diagram

This circuit is a complete LiPo battery power management system that includes charging, voltage regulation, protection, and multiple output rails (3.3V and boosted 5V). It is divided into functional blocks:

1. Input Power Section (USB & DC Connector)

The board accepts input power from:

USB connector (USB1)

DC jack (DC-005-20A)

Input protection includes:

TVS diode (SMAJ5.0A) (Note 4) to suppress voltage spikes

Schottky diodes to prevent reverse current flow

USB resistors (R10, R11 = 5.1kΩ) configure proper USB-C behavior.

2. On-Off Control Circuit

A physical switch (SW1) controls the ON_SIG signal.

A pull-down resistor (R6) (Note 5) ensures the system does not power up unintentionally.

This signal enables/disables regulators and boost circuits.

3. Battery Charging Circuit

Main IC: MCP73831T LiPo charger

Key features:

Supports charging from USB (max 500mA) or DC input (up to 1A)

Charge current is set by R2 (1kΩ) (Note 2)

→ Increasing/decreasing this resistor changes charging current.

Status LEDs (D7, D8, D9) indicate charging states.

Protection:

Input current limiting resistors and diodes

Capacitors (C1, C2) for filtering

Temperature sensing:

Placeholder resistor for thermistor (Note 3)

→ Can be replaced with a real battery temperature sensor.

Special mode:

Can operate as LDO (no battery) (Note 5)

→ Requires Vtherm > Vdd – 100mV (SEL configuration).

4. Battery Connector

JST connector provides connection to the 3.7V LiPo battery

Includes decoupling capacitor (C7 = 4.7µF) for stability.

5. 3.3V Regulator Section

IC: MCP1725 LDO regulator

Converts VBAT → stable 3.3V output (VCC)

Features:

Low dropout voltage

Enable control via ON_SIG

Capacitors:

Input/output capacitors ensure stability (Note 9: Cin ≥ Cout and placed close to VIN)

6. 5V Boost Converter Section

IC: MT3606 boost converter

Steps up battery voltage (3.0–4.2V) → 5V output

Output voltage set by resistor divider: Vo = 0.6 × (1 + R4/R5) (Note 7)

Inductor (L1 = 10µH) and diode (Schottky) are essential for boost operation.

Important limitation:

The MT3606 cannot fully disconnect output (Note 6)

→ Even when EN is LOW, leakage path from VBAT to 5V exists.

Schottky diode drop:

Around 0.35V at 2A (Note 8), affecting efficiency.

7. Load Switch / Power Gating

MOSFET array (Q1) controls power delivery to outputs.

Ensures safe switching of voltage rails.

Controlled via ON_SIG signal.

8. Output Header

Provides multiple accessible signals:

VCC (3.3V)

VBAT (raw battery voltage)

+5V (boost output)

PWR_GOOD

ON_SIG control

For Full Project:

https://electronicsworkshops.com/power-management-board-for-battery-powered-projects/

Conclusion

The LiPo Power Board presents a well-integrated and flexible solution for managing power in battery-operated electronic systems. By combining efficient LiPo charging, stable 3.3V regulation, and an adjustable boost converter for higher voltage needs, it supports a wide range of components within a single compact design. Additional features such as input protection, power control switching, and configurable charging parameters enhance its reliability and adaptability. Despite minor limitations like boost converter leakage, the overall design makes it highly suitable for prototyping and embedded applications requiring multiple voltage levels from a single LiPo battery.