供应开关电源芯片/NCP1253BSN65T1G

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   Current-Mode PWM Controller for Off-line Power Supplies The NCP1253 is a highly integrated PWM controller capable of delivering a rugged and high performance offline power supply in a tiny TSOP−6 package. With a supply range up to 28 V, the controller hosts a jittered 65 kHz or 100 kHz switching circuitry operated in peak current mode control. When the power on the secondary side starts to decrease, the controller automatically folds back its switching frequency down to a minimum level of 26 kHz. As the power further goes down, the part enters skip cycle while limiting the peak current. To avoid sub harmonic oscillations in CCM operation, adjustable slope compensation is available via the series inclusion of a simple resistor in the current sense signal. Besides the auto−recovery timer−based short−circuit protection, an Over Voltage Protection on the VCC pin protects the whole circuitry in case of optocoupler destruction or adverse open loop operation.

   NCP1253Features • Fixed−Frequency 65 kHz or 100 kHz Current−Mode Control Operation • Frequency Foldback Down to 26 kHz and Skip−Cycle in Light Load Conditions • Adjustable Ramp Compensation • Internally Fixed 4 ms soft−start • Timer−based Auto−Recovery or Latched Short−Circuit Protection • Frequency Jittering in Normal and Frequency Foldback Modes • Latched OVP on VCC • Up to 28 V VCC Operation • Extremely Low No−load Standby Power • These are Pb−Free Devices Typical Applications • Ac−dc Converters for TVs, Set−top Boxes and Printers • Offline Adapters for Notebooks and Netbooks