Product Description:

The KP321XB series is a high-performance, low-cost PWM control power switch designed for offline low-power step-down (buck) applications. It features a simple external circuit and requires few components. The device integrates a high-voltage MOSFET to enhance system surge withstand capability. Unlike traditional PWM controllers, the KP321XB has no fixed internal clock driving the MOSFET; instead, the system switching frequency automatically adjusts with load variations. The chip also employs a multi-mode PWM control technology, which effectively simplifies external circuit design, improves line and load regulation, and eliminates audible noise during system operation. Additionally, the internal peak current detection threshold automatically adjusts according to actual load conditions, effectively reducing standby power consumption under no-load conditions. The KP321XB integrates a complete set of self-recovery protection functions including: VDD undervoltage protection, cycle-by-cycle current limiting, output overvoltage protection, thermal protection, overload protection, and VDD overvoltage protection.

Features:

• Integrated 650V high-voltage MOSFET and high-voltage startup circuit

• Optimized light-load noise and enhanced system anti-interference capability

• Multi-mode control with noise-free operation

• Supports buck and buck-boost topologies

• Default 12V output (FB pin floating)

• Standby power consumption <50mW

• Excellent line and load regulation

• Integrated soft-start circuit

• Internal protection functions:

Overload protection (OLP)

Cycle-by-cycle current limiting (OCP)

Output overvoltage protection (OVP)

VDD overvoltage, undervoltage, and voltage clamp protection

• Package types: SOP-8 and DIP-8

Typical Applications:

• Small appliance power supplies

• Industrial control