Description

The UC184xA family of control ICs is designed for off-line fixed-frequency, current-mode switching power supplies. This product includes all the necessary features to implement power supplies with a minimum of external components, such as improved load regulation, pulse-by-pulse current limiting, and inherent protection of the power supply output switch.

Specifications and features

• Low start-up current (0.5mA max.)
• Trimmed oscillator discharge current (See Product Highlight)
• Optimized for off-line and DC-to-DC converters
• Automatic feed forward compensation
• Pulse-by-pulse current limiting
• Enhanced load response characteristics
• Under-voltage lockout with hysteresis
• Double pulse suppression
• High-current totem pole output
• Internally trimmed bandgap reference
• 500KHz operation
• Low offset error amplifier

Application Scenarios

The UC1843L is an appropriate choice for the following applications:

• Economical off-line flyback or forward converters
• DC-DC buck or boost converters
• Low-cost DC motor control

Comparison

• Improved load regulation
• Pulse-by-pulse current limiting
• Enhanced load response characteristics
• High-current totem pole output
• Low offset error amplifier

• Not suitable for applications requiring high precision
• Frequency and maximum duty cycle must be externally programmed
• Undervoltage lock-out requires 250µA typ. start-up current