Shenzhen Slkor micro Semicon Co., Ltd., recently released an application solution for the SL4054 constant current/constant voltage 500mA linear lithium battery charging management chip. Slkor is a Chinese high-tech enterprise specializing in integrated circuit design, production, sales, and technical services, with a focus on introducing new products utilizing semiconductor new materials and processes. The "Slkor" brand(www.slkoric.com) SL4054 product, following the SL40T120FL series IGBT and SLA333 operational amplifier, is tailored for handheld computers, MP3 players, Bluetooth headphones, digital cameras, small power adapters, PD fast charging, and other customer needs. To ensure that electronic product solution companies, product engineers, and electronics enthusiasts make the most of the SL4054, Slkor's engineering team collaborates with downstream factories to continuously optimize solutions.

Slkor® SL4054 charging management solutions are as follows：

1.1. Title: Slkor® SL4054 Linear Li-Ion Charger

1.2. Applications:USB-Powered Charging, Handheld Computers, MP3 Players, Bluetooth Headphones, Digital Cameras, Cellular Telephones, PDA.

1.3. Description:

The Slkor® SL4054 is a complete constant-current/constant-voltage linear charger for single cell lithium-ion batteries. Its SOP package and low external component count make the SL4054 ideally suited for portable applications. Furthermore, the SL4054 can work within USB and wall adapter. No blocking diode is required due to the internal PMOSFET architecture and have prevent to negative Charge Current Circuit. Thermal feedback regulates the charge current to limit the die temperature during high power operation or high ambient temperature. The charge voltage is fixed at 4.2V, and the charge current can be programmed externally with a single resistor. The SL4054 automatically terminates the charge cycle when the charge current drops to 1/10th of the programmed value after the final float voltage is reached. When removing input power automatically puts the SL4054 into a low current mode to reduce the battery's leakage current to below 2uA, and the shutdown mode reduces supply current to 45µA. Other features of SL4054 include current monitor, under voltage lockout, automatic recharge and two status pin to indicate charge termination and the presence of an input voltage. The Slkor® SL4054 is available in a SOT23-5 (ThinSOT^TM) package.

2. Slkor® SL4054 Typical Application Circuit:

3.1. Charging Cycle：

When the voltage on the V_cc pin rises above the UVLO threshold level and a precision 1% setting resistor is connected between the PROG pin and GND pin, or when a battery is connected to the charger output, the charging cycle begins. If the voltage on the BAT pin is below 2.9V, the charger enters trickle charging mode. In this mode, the SL4054 provides approximately 1/10 of the set charging current to raise the current voltage to a safe level for full current charging. When the voltage on the BAT pin rises above 2.9V, the charger enters constant current mode and supplies a constant charging current to the battery. When the voltage on the BAT pin reaches the final float charge voltage (4.2V), the SL4054 enters constant voltage mode and the charging current starts to decrease. The charging cycle ends when the charging current drops to 1/10 of the set value.

3.2. Constant Charge Current Setting：

Charge current is set by connecting a resistor R_ISET from PROG(Pin 5) to GND. The value of the resistor and the charging current are calculated as follow: (determine the resistance value of the resistor based on the desired charging current).

3.3. Charging Termination：

When the charging current reaches the final float voltage and decreases to 1/10 of the set value, the charging cycle is terminated. This condition is detected by monitoring the PROG pin using an internal filtering comparator. When the voltage on the PROG pin drops to 100mV, the charging is terminated. The charging current is cut off, and the SL4054 enters standby mode, with the input power current dropping to 45uA.

3.4. Undervoltage Lockout:

An internal undervoltage lockout (UVLO) circuit monitors the input voltage and keeps the charger in shutdown mode until V_CC rises above the UVLO threshold. If the UVLO comparator experiences a transition, the charger will not exit shutdown mode until V_cc rises above the battery voltage by 100mV.

4. BOM for Slkor® SL4054 Typical Application

Notes：

1. The operating current of the chip includes the current consumed by the external resistor connected to the PROG pin (approximately 100uA), but it does not include the current used by the chip to charge itself through the BAT pin (approximately 100mA).

2. The termination current for charging is typically 0.1 times the set charging current.

The Slkor® SL4054 is applied in a 500mA constant current/constant voltage desktop charger（一）

Mr. Song Shiqiang, the General Manager of Slkor (www.slkoric.com), introduced that the Slkor brand offers a range of products, including Silicon Carbide (SiC) SBD, SiC MOSFET, IGBT, Ultra-Fast Recovery Power Diode, as well as high, medium, and low voltage MOSFETs, SCR, bridge rectifiers, Schottky diodes, ESD protection diodes, TVS transient voltage suppressor diodes, general-purpose diodes, transistors, and power management chips such as LDO and AC-DC chips. Additionally, they provide Hall effect magnetic switch sensors, high-speed opto couplers, and other series of products that meet the demand for high-performance products in industries such as new energy vehicles, high-end equipment, communication and power equipment, solar photovoltaics, and medical devices. These products are also widely used in consumer electronics sectors such as smartphones, laptops, robots, smart homes, IoT, connected vehicles, LED outdoor lighting, and 3C digital products.

The Slkor® SL4054 is applied in a 500mA constant current/constant voltage desktop charger（二）

Slkor's universal models such as AMS1117-3.3, AMS1117-5.0, SS14, SS34, M7, SS8050, PC817C, 1N4148W, BAT54C, 2N7002, SMBJ6.5CA, SMBJ5.0A, SM4007PL, SD12C, ZMM5V1, SS310, MC34063S, SS36, LM2576S-5.0, BTA16-800B, 74HC595D, FR107, SL27517, SL27523, SL27524, MMBT5551, ULN2001D, and others are known for their stable quality and are well-received by customers. Shenzhen Kinghelm Electronics Co., Ltd. (www.kinghelm.net), also operated by Mr. Song Shiqiang, has been deeply involved in microwave and RF technology for over a decade. They provide customers with "kinghelm" brand products including Beidou GPS antennas, RF connectors, plug-ins, Type-C interfaces, RJ45 interfaces and terminals, automotive and motorcycle wiring harnesses, and more. Together with Slkor, they serve over 15,000 customers worldwide!

Slkor is committed to building the company into a professional, ecological, and inclusive platform. The Slkor official website offers sections for technical exchanges, featured columns by experts, data queries, electronic news, industry applications, and an electronic encyclopedia. The Slkor team integrates the spirit of unity, striving, openness, and pushing boundaries from sports into their work culture, forming the "Slkor Warriors Basketball Team." Upholding a company culture and corporate ethics of fairness, openness, cooperation, and mutual success, Slkor collaborates friendly with suppliers, agents, and customers to achieve synergistic development. They aim to “become a leading semiconductor company”in the near future.