LTC4054ES5 / LTC4054ES5-4.2—Single‑Cell Li‑Ion Linear Charger IC (SOT‑23‑5)🔋

The LTC4054ES5 / LTC4054ES5‑4.2 is a compact, high‑reliability linear battery charger IC for single‑cell Li‑Ion/Li‑Polymer batteries. Housed in a space‑saving SOT‑23‑5 package, it features a factory‑set 4.2 V charge termination (float) voltage and a simple, low‑component‑count design. Ideal for portable devices, embedded systems, and battery‑backed Arduino, Raspberry Pi, and other microcontroller projects, this IC delivers dependable performance across a wide range of electronics components and modules.

⚙️ Key Features

• Single‑cell Li‑Ion/Li‑Po charger with fixed 4.2 V float voltage
• Compact SOT‑23‑5 package for space‑constrained designs
• CC/CV charging algorithm for safe, consistent charging
• Minimal external components — no external MOSFET, sense resistor, or blocking diode required
• Thermal regulation helps maintain safe operation under high dissipation
• Programmable charge current via a single PROG resistor (application‑dependent)
• Charge status output (CHRG) for LED/MCU indication
• Automatic recharge and trickle precharge for deeply discharged cells
• Suitable for USB or 5 V wall‑adapter powered designs

📐 Technical Specifications

• Product: LTC4054ES5 / LTC4054ES5‑4.2
• Package: SOT‑23‑5 (ES5)
• Battery Chemistry: Single‑cell Li‑Ion / Li‑Polymer
• Charge Voltage (Float): 4.2 V (fixed)
• Charge Algorithm: Constant‑current / constant‑voltage (CC/CV) with automatic recharge
• Charge Current: Programmable via external resistor on PROG pin (refer to datasheet for limits)
• Status Indicator: CHRG open‑drain output for charge status
• Integration: Standalone, integrated design for effortless installation and use
• Typical Input Source: 5 V USB or wall adapter (observe datasheet input range and thermal limits)
• Pins (SOT‑23‑5): VCC, BAT, GND, PROG, CHRG

🔌 Typical Applications

• Battery charging systems for single‑cell Li‑Ion/Li‑Po packs
• Power supply circuits in portable and handheld electronics
• Embedded and IoT nodes, wearables, and sensor modules
• Arduino and Raspberry Pi battery backup (UPS) add‑ons and development boards
• Electronics modules and products operating around a 4.2 V battery float voltage

🧩 Design Notes

• Use only with single‑cell Li‑Ion/Li‑Po batteries. Do not use for multi‑cell packs in series.
• Provide adequate thermal management (copper area) for higher charge currents.
• Include appropriate battery protection circuitry (PCM/BMS) as required by your application.
• For precise limits (input voltage range, current programming, termination), consult the manufacturer’s datasheet.

✅ Why Choose This IC?

• Reliability and efficiency in a proven linear charger architecture
• Simple BOM and small footprint for rapid prototyping and production
• Seamless integration with microcontroller platforms and electronics components