NCP1252ADR2G

The NCP1252 hosts a high−performance current−mode controller specifically developed to drive power supplies designed for the ATX and the adapter market: - Current Mode operation: implementing peak current−mode control topology, the circuit offers UC384X−like features to build rugged power supplies. - Adjustable switching frequency: a resistor to ground precisely sets the switching frequency between 50 kHz and a maximum of 500 kHz. There is no synchronization capability. - Internal frequency jittering: Frequency jittering softens the EMI signature by spreading out peak energy within a band ±5% from the center frequency. - Wide Vcc excursion: the controller allows operation up to 28 V continuously and accepts transient voltage up to 30 V during 10 ms with Ivcc < 20 mA - Gate drive clamping: a lot of power MOSFETs do not allow their driving voltage to exceed 20 V. The controller includes a low−loss clamping voltage which prevents the gate from going beyond 15 V typical. - Low startup−current: reaching a low no−load standby power represents a difficult exercise when the controller requires an external, lossy, resistor connected to the bulk capacitor. The start−up current is guaranteed to be less than 100 μA maximum, helping the designer to reach a low standby power level. - Short−circuit protection: by monitoring the CS pin voltage when it exceeds 1 V (maximum peak current), the controller detects a fault and starts an internal digital timer.

Applications

• Power Supplies for PC Silver Boxes, Games Adapter...
• Flyback and Forward Converter

Key features

• Peak Current Mode Control
• Adjustable Switching Frequency up to 500 kHz
• Jittering Frequency ±5% of the Switching Frequency
• Latched Primary Over Current Protection with 10 ms Fixed Delay
• Delay Extended to 150 ms in E Version
• Delayed Operation Upon Start−up via an Internal Fixed Timer (A, B and C versions only)
• Adjustable Soft−start Timer
• Auto−recovery Brown−Out Detection
• UC384X−like UVLO Thresholds
• Vcc Range from 9 V to 28 V with Auto−recovery UVLO
• Internal 160 ns Leading Edge Blanking
• Adjustable Internal Ramp Compensation
• +500 mA - 800 mA Source / Sink Capability
• Maximum 50% Duty Cycle: A Version
• Maximum 80% Duty Cycle: B Version
• Maximum 65% Duty Cycle: C Version
• Maximum 47.5% Duty Cycle: D & E Versions
• Ready for Updated No Load Regulation Specifications
• SOIC−8 and PDIP−8 Packages
• These are Pb −Free Devices