NCP1308 ,Controller, Free Running Quasi-Resonant Current ModeELECTRICAL CHARACTERISTICS (For typical values T = 25°C, for min/max values T = 0°C to +125°C, Max ..
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NCP1308
Controller, Free Running Quasi-Resonant Current Mode
NCP1308
PWM Current-Mode
Controller for Free-Running
Quasi-Resonant OperationThe NCP1308 combines a true current mode modulator and a
demagnetization detector to ensure full borderline/Critical
Conduction Mode in any load/line conditions and minimum drain
voltage switching (Quasi-Resonant operation). Due to its inherent
skip cycle capability, the controller enters burst mode as soon as the
power demand falls below a predetermined level. As this happens at
low peak current, no audible noise can be heard. An internal 10 �s
timer prevents the free-run frequency to exceed a high frequency
(therefore below the 150 kHz CISPR-22 EMI starting limit), while
the skip adjustment capability lets the user select the frequency at
which the burst foldback takes place.
The Dynamic Self-Supply (DSS) drastically simplifies the
transformer design in avoiding the use of an auxiliary winding to
supply the NCP1308. This feature is particularly useful in
applications where the output voltage varies during operation (e.g.
battery chargers). Thanks to its high-voltage technology, the IC is
directly connected to the high-voltage DC rail. As a result, the
short-circuit trip point is not dependent upon any VCC auxiliary
level.
The transformer core reset detection is done through an auxiliary
winding which, brought via a dedicated pin. If an OVP is detected on
the VCC pin, the IC permanently latches off.
Finally, the continuous feedback signal monitoring implemented
with an Overcurrent fault Protection circuitry (OCP) makes the final
design 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•�AC-DC Adapters for Notebooks, etc.
•�Offline Battery Chargers
