Slkor SL4057 Linear Li-Ion Battery Charger: 500mA Single-Cell CC/CV Charging IC in SOT23-6 Package

In battery-powered products such as portable consumer electronics and small intelligent terminals, the integration level, charging accuracy, power consumption and package size of charging management ICs directly determine the charging safety, battery life and miniaturization level of end devices. Conventional linear charging solutions require numerous external components, feature low integration and occupy large PCB space, making them difficult to adapt to compact designs for portable products. The Slkor SL4057 is a constant current/constant voltage (CC/CV) linear charger designed specifically for single-cell lithium-ion batteries. Housed in a miniature SOT23-6 package, it integrates an on-chip power MOSFET and reverse blocking circuit, eliminating the need for external sense resistors and blocking diodes. It supports up to 500mA programmable charging current, and features thermal regulation, auto-recharge and multiple protection functions. With minimal external components and compatibility with USB and adapter power supplies, it is a highly integrated lithium battery charging solution for portable electronic devices.

1. Core Product Parameters

• Device Type: Single-cell lithium-ion battery linear charger
• Input Supply Voltage (VCC): 4.0V ~ 6.5V
• Float Voltage: 4.24V with ±1% accuracy
• Maximum Programmable Charging Current: 500mA
• Trickle Charge Threshold Voltage: 2.9V
• Standby Mode Quiescent Current: 25μA (typical)
• Sleep Mode Battery Leakage Current: ≤1μA
• Operating Ambient Temperature Range: -40℃ ~ 85℃
• Thermal Regulation Trigger Junction Temperature: 135℃
• Package: SOT23-6

2. Core Product Advantages

2.1 Highly Integrated Design with Minimal External Components

The chip integrates a power MOSFET, current sensing circuit and reverse blocking diode on-chip, eliminating the need for external sense resistors, power transistors and isolation devices. It significantly reduces external BOM count, saves PCB footprint and lowers overall solution cost, making it especially suitable for space-constrained portable electronic designs.

2.2 Complete Charging Profile with Intelligent Thermal Regulation

It supports a full three-stage charging process: trickle pre-charge, constant current charging and constant voltage charging. When battery voltage is below 2.9V, it pre-charges the battery with low current; once the voltage rises above the threshold, it switches to constant current fast charge; when approaching full charge, it enters constant voltage float charge mode, and automatically terminates charging when the current drops to 1/10 of the set value. A built-in thermal feedback loop automatically reduces charging current when the chip junction temperature exceeds 135℃, preventing overheating damage while maximizing charging rate, suitable for high-power charging scenarios.

2.3 High-Precision Charging Voltage with Programmable Charging Current

With a built-in high-precision voltage reference and resistor divider network, the 4.24V float voltage achieves ±1% accuracy, meeting the charging requirements of lithium-ion and Li-polymer batteries. Charging current can be flexibly set via an external resistor connected to the PROG pin, supporting up to 500mA. It can be matched to different battery capacities for optimized charging speed, with wide adaptability.

2.4 Low-Power Standby with Multiple Protection Mechanisms

Quiescent current in standby mode is as low as 25μA. When input voltage is removed, the device enters sleep mode with battery leakage current below 1μA, effectively reducing standby power loss and extending battery shelf life. It also integrates multiple protection mechanisms including undervoltage lockout (UVLO), soft-start inrush current limiting, battery reverse polarity protection and battery undervoltage protection, improving operational reliability of the charging system.

2.5 Dual Status Indicators with Auto-Recharge Function

Equipped with two open-drain status output pins, CHRG and STDBY, it can visually indicate various operating states such as charging in progress, charge complete, and no-battery fault. It supports external LED indicators or connection to a host controller for status detection. The built-in auto-recharge function continuously monitors battery voltage after charging completion, and automatically starts a new charging cycle when voltage drops below the recharge threshold, keeping the battery near full charge without additional control.

2.6 Compact SMD Package for Portable Applications

Adopting the ultra-compact SOT23-6 surface-mount package, the device features a small footprint, supports standard automated SMT assembly with consistent soldering quality, and fits high-density, compact PCB layouts. It is widely compatible with structural design requirements of various small portable electronic devices.

3. Main Application Fields

With its high integration, minimal external components, high-precision charging and comprehensive protection features, the SL4057 is widely used in various single-cell lithium battery powered portable products: mobile phones, PDAs, MP3/MP4 players, digital cameras, electronic dictionaries, Bluetooth headsets, GPS navigators, portable intelligent terminals and small lithium battery chargers.

4. Engineering Design Guidelines

Charging Current Configuration: Set charging current via an external resistor between the PROG pin and ground. Select resistance according to battery capacity: 2kΩ corresponds to 500mA, 5kΩ corresponds to 200mA. Refer to datasheet parameters for model selection. External Component Selection: It is recommended to place 1μF~10μF ceramic capacitors at the VCC input and BAT terminal respectively to filter power supply ripple and stabilize charging voltage and current. Thermal Optimization: For high-current charging scenarios, increase chip heat dissipation area through PCB copper pour to improve continuous charging capability and fully utilize the performance headroom of the thermal regulation function. Status Indicator Design: CHRG and STDBY are open-drain outputs. External pull-up resistors are required in application. They can directly drive LEDs or connect to MCU I/O ports for status acquisition. Protection Design: The chip features built-in battery reverse polarity protection. Ensure input voltage does not exceed the 6.5V upper limit to avoid overvoltage damage. It is recommended to widen input power traces to reduce the impact of line loss on charging accuracy.

5. Product Summary

The Slkor SL4057 is a highly integrated single-cell lithium-ion battery linear charging IC in a miniature SOT23-6 package. It integrates on-chip power transistors and sensing circuits, requires minimal external components, and delivers ±1% charging voltage accuracy, 500mA programmable current and a complete three-stage charging process. With thermal regulation, auto-recharge, dual status indicators and comprehensive protection functions, it balances charging performance, power consumption and design convenience, serving as a cost-effective domestic charging solution for various portable consumer electronics lithium battery applications.

Slkor introduction
According to Song Shiqiang, Slkor Semiconductor (https://www.slkormicro.com) grandly opened its third franchised store in Huaqiangbei on August 14, 2026. The store mainly offers MOSFETs, power-management ICs, Hall elements, optocouplers, IGBTs, SiC silicon-carbide components, AC/DC devices, TVS diodes, Schottky diodes, thyristors and other electronic components.



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