SC4056
1A linear Li-ion battery charger with automatic charge termination and thermal regulation in compact SOP-8 package
Product Overview
Description
The SC4056 is a complete constant-current/constant-voltage linear charger for single-cell lithium-ion batteries. Its compact SOP-8 package and low external component count make it ideal for portable applications.
The device charges the battery in three phases: conditioning, constant current, and constant voltage. Charge current is programmable up to 1A with an external resistor. When charge current drops to 1/10th of programmed value, charging automatically terminates.
Thermal feedback regulates charge current to limit die temperature, optimizing charge rate while protecting the IC. The SC4056 includes comprehensive protection features including reverse current protection and thermal shutdown.
Product Series
SC
Primary Application
Portable media players
Key Features
- Programmable charge current up to 1A
- No external MOSFET or blocking diode required
- Thermal regulation for maximum charge rate
- Automatic charge termination
- Automatic recharge threshold
- Reverse current protection
- SOP-8 package
Specifications
| Charge Current | Programmable up to 1A |
|---|---|
| Charge Voltage | 4.2V ±1% |
| Input Voltage | 4.5V to 6.5V |
| Standby Current | <2μA |
| Package | SOP-8 |
Applications
Portable media players
Electronic system design
Bluetooth headsets
Electronic system design
Power banks
Electronic system design
Portable medical devices
Medical electronics
Handheld instruments
Electronic system design
FAE Expert Insights
"The SC4056 is SouthChip's most popular linear charger and for good reason. It offers an excellent balance of features, performance, and cost. I've used this part in dozens of designs from TWS earbuds to portable medical devices. The 1A charge current is sufficient for most single-cell applications, and the thermal regulation works well to prevent overheating. The automatic recharge feature is useful for maintaining battery charge when the device remains connected to power. One tip: use a good quality 10μF ceramic capacitor at the BAT pin for stable operation. The charge current programming resistor should be placed close to the IC. Overall, this is a reliable workhorse charger for cost-sensitive applications."
Cost-effective linear charger with excellent reliability for single-cell Li-ion applications
— Michael Chen, BeiLuo
Frequently Asked Questions
What is the maximum charge current of SC4056?
The SC4056 supports programmable charge current up to 1A. The charge current is set by a resistor connected to the PROG pin using the formula: Ibat = 1000V / Rprog. For 1A charging, use 1kΩ resistor. For 500mA, use 2kΩ. The actual charge current may be limited by thermal regulation if the die temperature exceeds 120°C. At high charge currents with high input voltage, thermal regulation may reduce current to maintain safe temperature. For reliable 1A charging, ensure adequate PCB copper area for heat dissipation (minimum 0.5 square inches). The charge current can be monitored by measuring voltage at PROG pin: Vprog = Ibat × Rprog × 0.001.
Contact LiTong for charge current programming and thermal design guidance.
How does the automatic charge termination work?
The SC4056 automatically terminates charging when the charge current drops below 1/10th of programmed value during constant voltage phase. The process: (1) CC phase - Charger delivers constant current to battery until battery voltage reaches 4.2V. (2) CV phase - Charger maintains 4.2V while charge current gradually decreases as battery approaches full charge. (3) Termination - When charge current drops to C/10 (e.g., 100mA for 1A programmed current), charging terminates and CHRG pin enters high-impedance state. (4) Automatic recharge - If battery voltage drops below 4.05V (recharge threshold) after termination, new charge cycle begins. This ensures battery remains fully charged when left connected to power. The termination current threshold is fixed at C/10 and cannot be changed.
Contact LiTong for charge termination behavior and recharge threshold details.
What is the standby current consumption?
The SC4056 has very low standby current consumption: (1) Input standby current - Less than 2μA when input voltage present but not charging (battery full or no battery). (2) Battery drain current - Less than 2μA reverse current from battery to input when input power removed. (3) Shutdown current - Less than 25μA when manually shut down. These low currents ensure minimal battery drain when charger is idle. The reverse current protection prevents battery discharge through the charger when input power is removed. For battery-powered systems that remain connected to charger, this low standby current maximizes battery life. The actual standby current depends on input voltage and temperature, but typically stays below 2μA across operating range.
Contact LiTong for standby current specifications and battery drain analysis.
How does thermal regulation work?
The SC4056 thermal regulation system prevents overheating: (1) Temperature monitoring - Internal temperature sensor continuously monitors die temperature. (2) Regulation threshold - When die temperature exceeds approximately 120°C, charge current is automatically reduced. (3) Regulation loop - Charge current is reduced proportionally to temperature rise above threshold, maintaining temperature at regulation point. (4) Full current restoration - When temperature drops below threshold, charge current returns to programmed value. (5) Thermal shutdown - If temperature exceeds 150°C, charger shuts down completely until cooled. This allows charger to operate at maximum possible current without overheating, optimizing charge time while protecting the IC. Thermal regulation is automatic and requires no external components. Proper PCB layout with adequate copper area minimizes thermal regulation occurrence.
Contact LiTong for thermal design and heat dissipation optimization.
What is the recommended PCB layout?
Recommended PCB layout for SC4056: (1) Input capacitor - Place 10μF ceramic capacitor close to VCC and GND pins. Minimize loop area. (2) Output capacitor - Place 10μF ceramic capacitor close to BAT pin and GND. Critical for stability. (3) Thermal design - Use large copper areas connected to GND pin for heat dissipation. Minimum 0.5 square inches recommended for 1A charging. (4) PROG resistor - Place close to PROG pin with short trace to GND. Keep away from switching noise. (5) Battery connection - Keep traces to battery short and wide to minimize voltage drop. (6) Grounding - Use single-point ground connection. Avoid ground loops. (7) Thermal vias - Use thermal vias under GND pad to spread heat to inner layers. Following these guidelines ensures stable operation and maximum charge current capability. LiTong can provide reference layout and design review services.
Contact LiTong for PCB layout review and thermal design guidance.