With an elite team graduated from Beijing Tsinghua University, Shenzhen SlkorMicro Semicon Co., Ltd. is dedicated to the third generation semiconductor SiC power devices. Slkor is a national high-tech enterprise covering the R&D, production and sales service of semiconductor devices and provide reliable products and supporting technical services to customers.

In order to help electronic product solution companies, electronic application engineers, and electronics enthusiasts make the most of Slkor products, engineers from Slkor have selected typical cases from client applications to share with everyone.

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®4054 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 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. SL4054 Other features 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 VCC rises above the UVLO threshold. If the UVLO comparator experiences a transition, the charger will not exit shutdown mode until Vcc 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.

At Slkor, we are working hard to provide professional and comprehensive services. We have a complete product line ranging from the industrial applications to the military applications, SiC diodes, SiC MOSFET, IGBT, the 5th generation ultra fast recovery power diodes, etc. These products are vitally applied in electric vehicles, high-end equipments, communication equipments, electric power tools, solar photovoltaic systems and medical equipments and so on. For consumer products, we offer high and low voltage MOS, SCR, rectifier bridges, Schottky diodes, ESD protection diodes, TVS diodes, general-purpose diodes and transistors, power management ICs, Hall sensors, high-speed optical couplers, crystal oscillators, etc. These devices are widely applied to smart phones, laptops, intelligent robots, smart home appliances, IoT and IoV, LED lighting, 3C digital products and other fields. Please keep close contacts with us, we will launch more and more digital and analog IC products to meet your demands.

Solution Details:

Slkor® SL4054 Li-Ion Battery Management Solution (一)

Slkor® SL4054 Li-Ion Battery Management Solution (二)

Slkor® SL4054 Li-Ion Battery Management Solution (三)