ON Semiconductor NCP1207APG

Description
The NCP1207A/B is a PWM current-mode controller designed for free-running quasi-resonant operation. It 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. Due to its inherent skip cycle capability, the controller enters burst mode as soon as the power demand falls below a predetermined level. The NCP1207A has an internal 8.0 us timer that prevents the free-run frequency from exceeding 125 kHz, while the NCP1207B has a reduced timer duration of 4.5 us to allow operation at higher frequencies (up to 200 kHz).
The Dynamic Self-Supply (DSS) feature simplifies transformer design by eliminating the need for an auxiliary winding to supply the NCP1207A/B. The transformer core reset detection is done through an auxiliary winding which also enables fast Overvoltage Protection (OVP). Once an OVP has been detected, the IC permanently latches off.
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
No Auxiliary Winding Vec Operation
Auto-Recovery Overcurrent Protection
Latching Overvoltage Protection
External Latch Triggering, e.g. Via Overtemperature Signal
500 mA Peak Current Source/Sink Capability
Undervoltage Lockout for Vee Below 10 V
Internal 1.0 ms Soft-Start
Internal 8.0 us Minimum TOFF for NCP1207A, 4.5 μs Minimum TOFF for NCP1207B
Adjustable Skip Level
Internal Temperature Shutdown
Direct Optocoupler Connection
SPICE Models Available for TRANsient Analysis
Pb-Free and Halide-Free Devices

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