LTC4054 – LTH7 Standalone Linear Li-Ion Battery Charger SOT23-5

LTC4054 – LTH7 Standalone Linear Li-Ion Battery Charger is a complete constant-current/constant-voltage (CC/CV) charger specifically designed for single-cell Lithium-Ion (Li-Ion) batteries. This highly integrated device simplifies portable electronics design by eliminating the need for bulky external components. Its compact SOT23-5 package and minimal external circuit requirements make it an excellent choice for space-constrained applications like wearable devices, wireless headphones, and portable medical instruments. You program the charge current up to 800 mA using a single external resistor, providing flexibility for charging batteries of varying capacities. The charger automatically enters a low-power sleep mode when the input supply is removed, actively preventing battery drain.

Key Features:

• Complete Linear Charger: Integrates all power components, including the pass transistor, current sense, and reverse blocking diode.
• Programmable Charge Current: Allows you to set the charge current up to 800 mA using just one external resistor (R_PROG).
• Constant-Current/Constant-Voltage (CC/CV): Manages the charging process in two phases, ensuring safe and efficient battery charging.
• Thermal Regulation: Automatically limits the charge current to maintain safe junction temperature during high-power or high-ambient-temperature operation.
• Charge Status Output: Features an open-drain output (CHRG) that signals when the battery is charging or fully charged.
• Compact Package: Uses the tiny SOT23-5 package, saving significant board space.

Technical Specifications:

• Input Supply Voltage (V_IN): 4.25 V to 6.5 V
• Maximum Charge Current (I_MAX): Up to 800 mA
• Battery Float Voltage (V_FLOAT): 4.2 V ± 0.5% (Standard Li-Ion)
• Output Device: Phototriac Driver (Non-Zero Crossing)
• Termination Current: Typically 1/10th of the programmed charge current.
• Thermal Foldback Protection: Yes

Mechanical Specifications:

• Package Type: SOT23-5
• Mounting Style: Surface Mount Device (SMD/SMT)
• Operating Temperature Range: ≈ -40°C to +85°C

Dimensions:

• Footprint: ≈ 2.9 mm x 1.6 mm (SOT23-5 package)
• Height: ≈ 1.1 mm
• Weight: ≈ 0.01 g (Extremely lightweight)

Pinout and Wiring:

• Pin 1 (TEMP): Not used (internally tied high on LTH7 version).
• Pin 2 (GND): Connect to the ground potential.
• Pin 3 (V_IN): Connect to the input supply voltage (typically 5V via USB).
• Pin 4 (BAT): Connect to the positive terminal of the Li-Ion battery.
• Pin 5 (PROG): Connect a resistor (R_PROG) from this pin to GND to set the charge current.
• CHRG (External Pin): An open-drain output (requires a pull-up resistor) that pulls low when charging.

Datasheet Reference:

• Download LTC4054/LTH7 Datasheet

Commonly Used in:

• Wearable Electronics: Used due to its small size and high integration.
• USB-Powered Devices: Ideal for charging Li-Ion batteries directly from a standard 5V USB port.
• Bluetooth Accessories: Found in wireless earbuds, speakers, and peripherals.

Applications:

• Li-Ion Battery Charging: The primary function for single-cell packs.
• Portable MP3/Media Players: Managing power for internal batteries.
• Cordless Medical Devices: Ensuring reliable, safe power management in compact devices.

Equivalent Models:

• TP4056: A common alternative with a similar function but often a different package (SOP-8 or DIP-8) and current capability.
• MCP73831: Another family of low-cost, small-package linear Li-Ion chargers.
• BMS (Battery Management System) Modules: More complex systems that incorporate charging, protection, and balancing features.

Package Includes:

• 1 x LTC4054 – LTH7 Standalone Linear Li-Ion Battery Charger (SOT23-5)