NCP1562: High Performance Active Clamp/Reset PWM Controller

Datasheet: High Performance Active Clamp/Reset PWM Controller Rev. 4 (277.0kB)

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The NCP1562x is a family of voltage mode controllers designed for dc-dc converters requiring high efficiency and low parts count. These controllers incorporate two in phase outputs with an overlap delay to prevent simultaneous conduction and facilitates soft switching. The main output is designed for driving a forward converter primary MOSFET. The secondary output is designed for driving an active clamp circuit MOSFET, a synchronous rectifier on the secondary side, or an asymmetric half bridge circuit. The NCP1562 family reduces component count and system size by incorporating high accuracy on critical specifications such as maximum duty cycle limit, undervoltage detector and overcurrent threshold. Two distinctive features of the NCP1562 are soft-stop and a cycle skip current limit with a time threshold. Softstop circuitry powers down the converter in a controlled manner if a severe fault is detected. The cycle skip detector enables a softstop sequence if a continuous overcurrent condition is present. Additional features found in the NCP1562 include line feedforward, frequency synchronization up to 1.0 MHz, cycle by cycle current limit with leading edge blanking (LEB), independent under and overvoltage detectors, adjustable output overlap delay, programmable maximum duty cycle, internal startup circuit and soft-start.

Features		Benefits
Soft-Stop Powers Down Converter in a Controlled Manner		Eliminates Resonance Between Active Clamp Capacitor and Primary Inductance
Independent Line Undervoltage and Overvoltage Detectors		Reduces External components
Programmable Maximum Volt-Second Product		Prevents Transformer Saturation
Programmable Soft-Start		Reduces Stress During Power Up
Internal 100 V Startup Circuit		Eliminates the Need for External Components
Dual Outputs with Adjustable Overlap Delay
>2 A Output Drive Capability
Cycle-by-Cycle Current Limit
Cycle Skip Initiated if Continuous Current Limit Condition Exists
Voltage Mode Operation with Input Voltage Feedforward
Fixed Frequency Operation up to 1 MHz
Bidirectional Frequency Synchronization
Accurate Programmable Maximum Duty Cycle
Precision 5 V Reference

Applications		End Products
High power isolated DC/DC converters Power supplies		Desktop / Server PSU Telecom base station PSU Flat TV PSU

Technical Information
Design & Development Tools (1)	Selector Guides (1)
Reference Designs (2)	Data Sheets (1)
Application Notes (1)	Package Drawings (2)