onsemi NCP1217AD100R2G

Housed in an SO−8 or PDIP−7 package, the NCP1217 represents the enhanced version of the NCP1203−based controllers. Due to its high drive capability, NCP1217 drives large gate−charge MOSFETs, which together with internal ramp compensation and built−in overvoltage protection, ease the design of modern AC/DC adapters. NCP1217 offers a true alternative to UC384X−based designs. With an internal structure operating at different fixed frequencies (65−100−133 kHz), the controller features a high−voltage startup FET, which ensures a clean and loss less startup sequence. Its current−mode control topology provides an excellent input audio−susceptibility and inherent pulse−by−pulse control. Internal ramp compensation easily prevents subharmonic oscillations from taking place in continuous conduction mode designs. 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 NCP1217 features two efficient protective circuitries: 1) In presence of an overcurrent condition, the output pulses are disabled and the device enters a safe burst mode, trying to restart. Once the default has gone, the device auto−recovers. 2) If an external signal (e.g. a temperature sensor) pulls Pin 1 above 3.2 V, output pulses are immediately stopped and the NCP1217 stays latched in this position. Reset occurs when the VCC collapses to ground, e.g. the user unplugs the power supply. The NCP1217 implements a standard current mode architecture where the switch−off event is dictated by the peak current setpoint. This component represents the ideal candidate where low part−count is the key parameter, particularly in low−cost AC/DC adapters, TV power supplies, etc. Due to its high−performance High−Voltage technology, the NCP1217 incorporates all the necessary components normally needed in UC384X based supplies: timing components, feedback devices, low−pass filter and startup device but also enhances the original component by offering: 1) an externally triggerable latchoff 2) ramp compensation and finally, 3) short−circuit protection. Due to its high−voltage current source, the NCP1217 does not need an external startup resistance but supplies the startup current directly from the high−voltage rail.

• Current−Mode with Adjustable Skip−Cycle Capability
• Built−in Internal Ramp Compensation
• Auto−Recovery Internal Output Short−Circuit Protection
• Internal 1.0 ms Soft−Start (NCP1217A Only)
• Limited Duty−Cycle to 50% (NCP1217A Only)
• Full Latchoff if Adjustment Pin is Brought High
• Extremely Low No−Load Standby Power
• Internal Temperature Shutdown
• 500 mA Peak Current Capability
• Fixed Frequency Versions at 65 kHz, 100 kHz and 133 kHz
• Direct Optocoupler Connection
• Internal Leading Edge Blanking
• SPICE Models Available for TRANsient and AC Analysis
• These are Pb−Free Devices

• High Power AC/DC Converters for TVs, Set−Top Boxes, etc.
• Offline Adapters for Notebooks
• Telecom DC−DC Converters
• All Power Supplies