This power management circuit is designed for IoT applications that require advanced functionality and reliable energy control. It supports the integration of a rechargeable battery cell, specifically lithium-ion (Li⁺) chemistry. The system includes a fuel gauge with an I²C interface, enabling real-time monitoring of battery capacity by a microcontroller (MCU) or system-on-chip (SoC).
One of the critical features of the design is the power-on reset mechanism, which ensures the MCU or SoC starts in a known, stable state—preventing erratic behavior or malfunction during power fluctuations.
The circuit also employs active power path management, which intelligently manages power distribution between the battery, load, and charging source to optimize efficiency and protect components. This is implemented using the BQ24195power management IC.
The schematic of the power management circuit is shown below.
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| Schematic Design |
This schematic illustrates a comprehensive power management circuit designed for IoT applications, integrating battery charging, regulation, and monitoring functionalities. At its core, the BQ24195L IC (U2) manages power path control and charges a single-cell Li-ion battery from a USB input (Port1). It ensures efficient switching between external power and battery supply while providing regulated output to the system.
The MAX17043 (U3) fuel gauge monitors the battery's state-of-charge and voltage via I²C, enabling accurate battery management by an MCU or SoC. To supply a stable 3.3V logic rail, a TPS70948 low-dropout regulator (U4) is used, fed from the system output. The design includes a variety of passive components for filtering, current limiting, and signal conditioning. Additionally, a power-on reset mechanism and status indicators are integrated to enhance system reliability. This circuit is well-suited for low-power, battery-operated embedded systems requiring intelligent power management.
