NCP1256 Current Mode Controller

By ON Semiconductor 313

NCP1256 Current Mode Controller

ON Semiconductor's NCP1256 includes everything to build cost-effective switch mode power supplies ranging from a few watts up to several tens of watts. Housed in a tiny TSOP-6 package, the part can be supplied up to 30 V. It hosts a jittered 65 kHz or 100 kHz switching circuitry operated in peak current mode control. When the power in 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. NCP1256 comes with several protection features such as a timer-based auto-recovery short circuit protection, lossless overpower protection (OPP), and an easily adjustable brownout (BO) pin. Two inputs are provided to latch off the part in a practical way, for instance with overvoltage protection (OVP) and overtemperature protection (OTP) events. Several options exist to choose latch or auto-recovery.

Features
  • Frequency foldback down to 26 kHz and skip-cycle in light load conditions
  • More efficient light load operation
  • 70-ms timer-based, auto-recovery, short-circuit protection
  • Short circuit operation for safety, yet reliable with auto-recovery for flexible restart
  • Frequency jittering in normal and frequency foldback modes
  • Jitter reduces EMI by spreading the switching spectrum over a wider band
  • +500 mA / -500 mA source / sink drive capability
  • Ability to drive larger FETs
  • Pb-free device
  • Environment friendly
  • Fixed−frequency 65-kHz or 100-kHz current-mode control operation
  • Adjustable OPP circuit, disabled at low line
  • Adjustable BO level
  • Internally fixed slope compensation ramp
  • Internally fixed 4-ms soft-start
  • Double hiccup auto-recovery short-circuit protection
  • Pre-short ready for latched OCP option
  • Latched OVP protection on VCC
  • Latched inputs for improved robustness (OVP and OTP implementations)
  • EPS 2.0 compliant
Applications
  • AC-DC adapters for portable devices
  • AC-DC adapters for computers
  • AC-DC adapters for tablets
  • General AC-DC adapters

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