Product Overview NCP1251: PWM Controller, Current Mode, for Offline Power Supplies For complete documentation, see the data sheet Product Description The NCP1251 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. Over Power Protection (OPP) is a difficult exercise especially when no-load standby requirements drive the converter specifications. The ON proprietary integrated OPP lets you harness the maximum delivered power without affecting your standby performance simply via two external resistors. A latched Over Voltage Protection (OVP) is combined on the same pin. For ease of implementation, an auto-recovery OVP also monitors the Vcc line. These features offer an efficient protection in case of optocoupler failure or adverse open loop operation. Finally, a timer-based short-circuit protection offers the best protection scheme, letting you precisely select the protection trip point irrespective of a loose coupling between the auxiliary and the power windings. Features Benefits • Non-dissipative internal and adjustable Over Power Protection (OPP) • Frequency Foldback down to 26 kHz and Skip-Cycle in light load conditions • Internal Ramp Compensation • Frequency jittering from full load to skip-cycle • Latch input for OVP and OTP implementations • Over Voltage Protection (OVP) monitoring on the Vcc pin • Limits maximum delivered power without affecting standby performance • High efficiency in light load conditions • • • • Reduces the number of external components Improved EMI performance Simple implementation of required protection functions Protects against output over voltage conditions without any added components • See NCP1250 for no Over Voltage Protection (OVP) on the Vcc pin Applications End Products • Offline Adapters • AC-DC converters • 45W Adapter • Set-top Boxes • Printers • Notebooks and Netbooks Part Electrical Specifications Product Compliance Status Topolog y Control Mode fsw Typ (kHz) StandUVLO by Mode (V) Short Circuit Protecti on Latch Soft Start VCC Max Drive (V) Cap. (mA) Packag e Type NCP1251ASN100T1G Pb-free Active Flyback Current Mode 100 Yes 8.8 Yes Yes Yes 28 300 / 500 TSOP-6 Active Flyback Current Mode 65 Yes 8.8 Yes Yes Yes 28 300 / 500 TSOP-6 Active Flyback Current Mode 100 Yes 8.8 Yes OVP Yes 28 300 / 500 TSOP-6 Active Flyback Current Mode 65 Yes 8.8 Yes OVP Yes 28 300 / 500 TSOP-6 Active Flyback Current Mode 65 Yes 8.8 Yes NO Yes 28 300 / 500 TSOP-6 Active Flyback Current Mode 65 Yes 8.8 Yes Yes Yes 28 300 / 500 TSOP-6 Halide free NCP1251ASN65T1G Pb-free Halide free NCP1251BSN100T1G Pb-free Halide free NCP1251BSN65T1G Pb-free Halide free NCP1251CSN65T1G Pb-free Halide free NCP1251FSN65T1G Pb-free Halide free Application Diagram For more information please contact your local sales support at www.onsemi.com Created on: 6/30/2016