NCP1200A
PWM Current−Mode Controller for Universal Off−Line Supplies Featuring Low Standby Power

Housed in SOIC−8 or PDIP−8 package, the NCP1200A enhances the previous NCP1200 series by offering a reduced optocoupler current together with an increased drive capability. Due to its novel concept, the circuit allows the implementation of complete off−line AC−DC adapters, battery charger or a SMPS where standby power is a key parameter.
With an internal structure operating at a fixed 40 kHz, 60 kHz or 100 kHz, the controller supplies itself from the high−voltage rail, avoiding the need of an auxiliary winding. This feature naturally eases the designer task in battery charger applications. Finally, current−mode control provides an 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 a user adjustable low peak current, no acoustic noise takes place.
The NCP1200A features an efficient protective circuitry which, in presence of an overcurrent condition, disables the output pulses while the device enters a safe burst mode, trying to restart. Once the default has gone, the device auto−recovers.

Features
• Pb−Free Packages are Available
• No Auxiliary Winding Operation
• Auto−Recovery Internal Output Short−Circuit Protection
• Extremely Low No−Load Standby Power
• Current−Mode Control with Skip−Cycle Capability
• Internal Temperature Shutdown
• Internal Leading Edge Blanking
• 250 mA Peak Current Capability
• Internally Fixed Frequency at 40 kHz, 60 kHz and 100 kHz
• Direct Optocoupler Connection
• SPICE Models Available for TRANsient and AC Analysis
• Pin to Pin Compatible with NCP1200

Typical Applications
• AC−DC Adapters for Portable Devices
• Offline Battery Chargers
• Auxiliary Power Supplies (USB, Appliances, TVs, etc.)

MAXIMUM RATINGS

Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not implied, damage may occur and reliability may be affected.



Typical Application Example

Internal Circuit Architecture



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