The UTC3842E is a high-performance fixed frequency current-mode PWM controller specifically designed for off-line and DC-to-DC converter applications. It offers a cost-effective solution with minimal external components.

Applications

• Switching Power Supplies
• DC-DC Converters
• Battery Chargers
• Uninterruptible Power Supplies (UPS)
• Adapters

Features

• Low Start-up Current
• Optimized for Off-Line Converters
• Current Mode Operation
• Automatic Feed Forward Compensation
• Trimmed Oscillator for Precise Duty Cycle Control
• Overvoltage Protection
• Undervoltage Lockout

Benefits

• Reduces power consumption during start-up
• Enhanced noise immunity
• Simplified loop compensation
• Precise and stable duty cycle operation
• Protects the power supply from overvoltage conditions
• Prevents malfunction due to low supply voltage

Additional Details

The UTC3842E operates at a fixed frequency, typically around 500kHz, and offers current-mode control for improved stability and transient response. The IC includes an internal oscillator, error amplifier, current sense comparator, and PWM logic. The output duty cycle is determined by the voltage on the current sense input and the error amplifier output. Protection features include overvoltage protection and undervoltage lockout. The UTC3842E is commonly available in DIP-8 and SOP-8 packages. An external resistor and capacitor set the oscillator frequency. This IC is widely used in flyback, forward, and other converter topologies. A small external compensation network is typically required to ensure loop stability. The under-voltage lockout (UVLO) feature prevents the IC from operating until the supply voltage reaches a specified threshold.

The device regulates the output voltage by controlling the duty cycle of the PWM signal, thus controlling the amount of power delivered to the load.