The KA3845A is a fixed frequency current-mode PWM controller specifically designed for off-line and DC-to-DC converter applications. This integrated circuit offers the necessary features to implement a cost-effective and reliable power supply control scheme. Its versatility and robust design make it suitable for a wide range of power electronics applications.

Applications

• Switch-Mode Power Supplies (SMPS)
• DC-DC Converters
• Offline Power Converters
• Uninterruptible Power Supplies (UPS)
• Battery Chargers

Features

• Optimized for Off-Line and DC-to-DC Converters
• Low Start-Up Current
• Automatic Feed Forward Compensation
• Latching PWM for Cycle-By-Cycle Current Limiting
• Internally Trimmed Reference with UVLO
• High Current Totem-Pole Output
• Under-Voltage Lockout (UVLO) with Hysteresis
• Low Operating Current
• Adjustable Duty Cycle Control

Benefits

• Cost-effective solution for power supply control
• Improved efficiency due to current-mode operation
• Enhanced reliability with built-in protection features like UVLO and current limiting
• Simplified design process due to integrated functionality
• Stable operation over a wide range of input voltages and load conditions
• Reduced component count, leading to smaller and more compact power supply designs

Additional Details

The KA3845A operates at a fixed switching frequency, typically around 500kHz, determined by an external resistor and capacitor. The current-mode control scheme provides inherent line feedforward compensation, improving the converter's response to input voltage variations. The internal latching PWM ensures cycle-by-cycle current limiting, protecting the power switch from overcurrent conditions. The UVLO circuit prevents the controller from operating at low input voltages, preventing erratic behavior. The high-current totem-pole output is capable of directly driving a power MOSFET. This device is typically available in an 8-pin DIP or SOIC package. The operating temperature range is typically -40°C to +85°C. The supply voltage range is usually up to 30V. The precise switching frequency is determined by an external resistor and capacitor. This controller delivers a reliable and stable performance in various power supply designs.