The **SK6908L-S08-R** is a high-performance, integrated current-mode PWM controller designed specifically for low-power offline SMPS (Switched-Mode Power Supply) applications. It is commonly used in battery chargers and power adapters. ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Package Type** | SOP-8 (Surface Mount) | | **Control Method** | Current Mode PWM | | **Startup Current** | Very Low (typically < 10µA) | | **Operating Frequency** | Fixed with Jittering for EMI | | **Standby Power** | < 75mW (Extended Green Mode) | | **Protection Features** | OVP, OLP, SCP, OTP | --- ### 2. Functional Description The device integrates several advanced features to improve efficiency and reliability in power conversion: * **Green-Mode Function:** To comply with standby power regulations, the controller reduces its switching frequency under light-load or no-load conditions. * **EMI Management:** It features frequency shuffling (jittering), which spreads the harmonic energy over a wider range, making it easier to meet EMI standards with smaller filters. * **Internal Compensations:** * **Slope Compensation:** Prevents sub-harmonic oscillations at high duty cycles. * **Leading Edge Blanking (LEB):** Filters out the initial current spike when the MOSFET turns on, preventing false triggering of the current limit. --- ### 3. Pin Configuration (SOP-8) | Pin No. | Pin Name | Description | | :--- | :--- | :--- | | 1 | **GND** | Ground reference. | | 2 | **FB** | Feedback input to regulate the output voltage. | | 3 | **RI / V_SNS** | Internal oscillator frequency setting or line sensing. | | 4 | **SENSE** | Current sense input for peak current control. | | 5 | **VDD** | Power supply pin for the IC. | | 6 | **NC** | No connection. | | 7 | **GATE** | Totem-pole output to drive the external Power MOSFET. | | 8 | **NC** | No connection. | --- ### 4. Typical Application Circuit The SK6908L is typically used in a **Flyback Converter** topology. ```mermaid graph LR AC_Input --> Rectifier/Filter Rectifier/Filter --> Transformer_Primary Transformer_Primary --> MOSFET SK6908L_GATE --> MOSFET Optocoupler --> SK6908L_FB Transformer_Secondary --> Output_DC ``` ### 5. Protection Mechanisms * **OVP (Over Voltage Protection):** Shuts down the IC if VDD exceeds a safe threshold. * **OLP (Over Load Protection):** Limits power if the output is overloaded for a specific duration. * **OTP (Over Temperature Protection):** Thermal shutdown if the internal junction temperature exceeds limits. ---