TP4054 Development Project with Buck Boost Regulator

Li-Ion USB Charger with Buck/Boost Output and Status Indicator

This project is a compact USB-powered Li-Ion charging and power supply module designed around the TP4054 and TPS63000 ICs. It provides USB charging functionality for a single-cell 3.7V Li-Ion battery and delivers a regulated 5V output through a buck/boost converter. Ideal for portable projects, USB power banks, and embedded devices requiring reliable 5V output.

🔌 Key Features:

• Micro USB input for charging via VBUS (USB 5V).

• TP4054 linear charger for safe and controlled charging of a single 3.7V Li-Ion cell.

  • Charging current set to ~470 mA via external resistor (R10).

  • Input protected with a PTC fuse (1A).

• TPS63000 buck/boost converter:

  • Converts battery voltage (2.5–4.2 V) to a stable 5V output.

  • Handles both step-up and step-down operation automatically.

  • Efficient power delivery even when battery is partially drained.

• USB-A output port with RH7019A data line resistor IC for USB device recognition (Apple/Android compatibility).

• Output filtering includes multiple capacitors and an inductor for clean, stable power.

• Reverse current protection with a Schottky diode between battery and regulator input.

🔵 Charge Status LED via Op-Amp Buffer:

The CHRG pin of the TP4054 is an open-drain output with a weak internal pull-up resistor, making it unsuitable for directly driving an LED. To solve this, an NE5532 op-amp is used as a voltage follower (buffer), allowing the CHRG signal to drive a blue LED cleanly. The LED lights up when the battery is fully charged, providing a clear visual indicator.

🛡️ Protections and Filtering:

• Reverse current protection (B5819W).

• ESD and inrush current protection at USB input.

• Decoupling and filtering capacitors throughout for stable operation.

• Fuse protects USB source from short circuits or overloads.