1. Overview

️· Design Goal: This document details the design of a small, low-cost flyback power supply for a 6V, 330mA output.
️· Key Component: Uses the Power Integrations LNK564 LinkSwitch-LP controller.
️· Topology: Flyback converter (discontinuous or continuous mode - it's configurable).
️· Emphasis: Focus on cost optimization and simplicity.
️· Target Application: Likely a small consumer electronic device or a charging application.

2. Key Design Specifications

️· Input Voltage: 90-265 VAC (universal input).
️· Output Voltage: 6.0 VDC
️· Output Current: 330 mA
️· Output Power: ~2 Watts
️· Output Cable Resistance: 0.05 Ohms. This is factored into calculations.
️· Efficiency: Target of around 70% (estimated)
️· Feedback Type: Bias winding feedback. This helps to reduce no-load power consumption.

3. Core Components & Materials

️· Controller: Power Integrations LNK564 LinkSwitch-LP
️· Transformer Core: EE16 core (a common, relatively inexpensive core size).
️· Bobbin: EE16 bobbin.
️· Materials: Standard magnet wire, isolation tape, barrier tape.

4. Transformer Design Details

️· Transformer Winding Configuration:
- Primary: 108 turns of 0.14mm wire.
- Secondary: 8 turns of 0.25mm x 3 (litz wire)
- Bias Winding: 27 turns of 0.2mm wire.
️· Electrical Specifications:
- Primary Inductance: 2.7 mH
- Primary Leakage Inductance: 75 µH (max)
- Primary Winding Capacitance: 50 pF (max)
️· Construction Details:
- Layering instructions for the windings.
- Specifics for starting the shield winding. (important for EMI performance)
- Emphasis on ensuring no empty spaces among wires for better winding density.

5. Key Design Calculations & Parameters

️· AL Value: 1140 nH/T² (Core factor, important for inductance calculation).
️· Core Effective Area (Ae): 0.192 cm²
️· Effective Path Length (Le): 3.5 cm
️· Secondary Voltage: Calculated based on the required output voltage and turns ratio.
️· Bias Winding Voltage: 21.93V
️· Resistor Divider: R1 is 36.89k ohms.
️· I²f Parameters: These relate to the controller's current limiting and frequency trimming, used for tighter tolerance.

6. Design Considerations

️· Clampless Design: The design is specified as "clampless," meaning it doesn't rely on an external clamp circuit. This simplifies the design but may require more careful control of leakage inductance.
️· Bias Winding: The inclusion of a bias winding is for lower no-load power consumption.
️· Efficiency: The design aims for around 70% efficiency.
️· Safety and Isolation: The document emphasizes isolation, especially in the transformer construction, for safety.
️· EMI Performance: The details about the shield winding are directly related to reducing electromagnetic interference (EMI).

In essence, this document provides a complete design guide for a very simple and cost-optimized flyback power supply, geared toward high-volume production. It is a good example of how to design a power supply with a minimum number of components and a focus on manufacturability.