NCP1200: Current Mode Controller Fixed Frequency Operation

Datasheet: PWM Current-Mode Controller for Low-Power Universal Off-Line Supplies Rev. 16 (255.0kB)

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Housed in SO-8 or DIP-8 package, the NCP1200 represents a major leap toward ultra-compact Switch-Mode Power Supplies. Thanks to a novel concept, the circuit allows the implementation of a complete offline battery charger or a standby SMPS with few external components. Furthermore, an integrated output short-circuit protection lets the designer build an extremely low-cost AC/DC wall adapter associated with a simplified feedback scheme.

With an internal structure operating at a fixed 40 kHz, 60 kHz or 100 kHz, the controller drives low gate-charge switching devices like an IGBT or a MOSFET thus requiring a very small operating power. Thanks to current-mode control, the NCP1200 drastically simplifies the design of reliable and cheap offline converters with excellent audio- susceptibility and inherent pulse-by-pulse control.

When the current setpoint falls below a given value, e.g. the output power demand diminishes, the IC automatically enters the so-called skip cycle mode and provides excellent efficiency at light loads. Because this occurs at low peak current, no acoustic noise takes place.

Finally, the IC is self-supplied from the DC rail, eliminating the need of an auxiliary winding. This feature ensures operation in presence of low output voltage or shorts.

Features
No Auxiliary Winding Operation
Internal Output Short-Circuit Protection
Extremely Low No-Load Standby Power
Current-Mode with Skip-Cycle Capability
Internal Leading Edge Blanking
250 mA Peak Current Source/Sink Capability
Internally Fixed Frequency at 40 kHz, 60 kHz and 100 kHz
Direct Optocoupler Connection
Built-in Frequency Jittering for Lower EMI
SPICE Models Available for TRANsient and AC Analysis
Internal Temperature Shutdown
Pb-Free Packages are Available

Applications
AC/DC Adapters Offline Battery Chargers Auxiliary/Ancillary Power Supplies (USB, Appliances, TVs, etc.)

Technical Information
Design & Development Tools (3)	Selector Guides (1)
Application Notes (10)	Data Sheets (1)
Simulation Models (3)	Package Drawings (2)