## Overview of the STR-W6764 (STRW6764) The **STR-W6764** (often referred to in parts lists as STRW-64 series) is a thick-film integrated circuit designed for **Quasi-Resonant** switching power supplies. It is manufactured by Sanken Electric Co. and is widely used in television sets, home appliances, and industrial power adapters. ### 1. Key Internal Components The IC integrates several high-performance electronic parts into a single TO-220F package: | Component | Function | | :--- | :--- | | **Power MOSFET** | An avalanche-guaranteed high-voltage MOSFET that handles the main switching load. | | **Control IC** | A low-power CMOS controller that manages timing, startup, and feedback. | | **Startup Circuit** | Reduces external component count and standby power consumption. | | **Protection Circuits** | Integrated Overcurrent (OCP), Overvoltage (OVP), and Overload (OLP) sensors. | --- ### 2. Technical Specifications The device is optimized for efficiency and safety. Below are the typical parameters for the STR-W6764 variant: | Parameter | Value / Description | | :--- | :--- | | **Maximum Voltage ($V_{DSS}$)** | 650V | | **Drain Current ($I_{D}$)** | 9.5A (Pulse) / 3.4A (Continuous) | | **Operating Mode** | Quasi-Resonant (QR) + Bottom-Skip PWM | | **Package Type** | TO-220F-6L (Insulated) | | **Standby Power** | Ultra-low (Automatic Switching to Burst Mode) | --- ### 3. Pin Configuration The "RTR" suffix often refers to the taping or lead-forming style, but the functional pins remain standard: 1. **Drain (D):** Connection to the primary winding of the transformer. 2. **Source (S):** Ground/Current sense connection. 3. **VCC:** Power supply input for the internal control logic. 4. **SS/OLP:** Soft Start and Overload Protection timing pin. 5. **FB:** Feedback input (connected to the optocoupler). 6. **OCP/BD:** Overcurrent Protection and Bottom Detection (for QR switching). --- ### 4. Distinctive Features * **Quasi-Resonant Switching:** This reduces switching losses and electromagnetic interference (EMI) by turning on the MOSFET at the lowest voltage point (valley) of the resonance. * **Bottom-Skip Function:** At light loads, the IC skips switching cycles to maintain high efficiency and prevent audible noise. * **Auto-Bias Function:** Stabilizes the VCC voltage during standby mode, ensuring the power supply doesn't drop out. --- ### 5. Common Applications * LCD/LED TV Power Boards. * Multi-function Printers. * DVD/Blu-ray Players. * AC/DC Power Adapters.