Onsemi NCP1308

Description

The NCP1308 combines a true current mode modulator and ademagnetization detector to ensure full borderline/CriticalConduction Mode in any load/line conditions and minimum drainvoltage switching (Quasi-Resonant operation). Due to its inherentskip cycle capability, the controller enters burst mode as soon as thepower demand falls below a predetermined level. As this happens atlow peak current, no audible noise can be heard. An internal 10 stimer prevents the free-run frequency to exceed a high frequency(therefore below the 150 kHz CISPR-22 EMI starting limit), whilethe skip adjustment capability lets the user select the frequency atwhich the burst foldback takes place.

The Dynamic Self-Supply (DSS) drastically simplifies thetransformer design in avoiding the use of an auxiliary winding tosupply the NCP1308. This feature is particularly useful inapplications where the output voltage varies during operation (e.g.battery chargers). Thanks to its high-voltage technology, the IC isdirectly connected to the high-voltage DC rail. As a result, theshort-circuit trip point is not dependent upon any VCC auxiliarylevel.

The transformer core reset detection is done through an auxiliarywinding which, brought via a dedicated pin. If an OVP is detected onthe VCC pin, the IC permanently latches off.

Finally, the continuous feedback signal monitoring implementedwith an Overcurrent fault Protection circuitry (OCP) makes the finaldesign rugged and reliable.

Features

• Free-Running Borderline/Critical Mode Quasi-Resonant Operation
• Current-Mode with Adjustable Skip Cycle Capability
• Dynamic Self-Supply Type of VCC
• Auto-Recovery Overcurrent Protection
• Improved UVLO for VCC below 10 V
• Latching Overvoltage Protection on VCC
• 500 mA Peak Current Source/Sink Capability
• Internal 1.0 ms Soft-Start
• Internal 10 s Minimum TOFF
• Adjustable Skip Level
• Internal Temperature Shutdown
• Internal Leading Edge Blanking
• Direct Optocoupler Connection
• SPICE Models Available for TRANsient Analysis
• This is a Pb-Free Device

Typical applications

• Offline Battery Chargers
• Auxiliary Power Supplies (USB, Appliances, TVs, etc.)
• Consumer Electronics (DVD Players, Set-Top Boxes, TVs, etc.)
• AC-DC Adapters for Notebooks, etc.

More information

• Datasheet
• IC product information