High Efficiency 5A, 24V, 500kHz Synchronous Step-down Converter



The NB634 is a high efficiency synchronous rectified step-down switch mode converter with built-in internal power MOSFETs. It offers a very compact solution to achieve 5A continuous output current over a wide input supply range with excellent load and line regulation. The NB634 operates at high efficiency over a wide output current load range. Current mode operation provides fast transient response and eases loop stabilization. Full protection features include latch-off OCP and thermal shut down. The NB634 requires a minimum number of readily available standard external components and is available in a space saving QFN14 (3mm x 4mm) package.



  • Wide 4.5V to 24V Operating Input Range
  • 5A Output Current
  • Low RDS(ON) Internal Power MOSFETs
  • Proprietary Switching Loss Reduction Technique
  • Fixed 500kHz Switching Frequency
  • Sync from 300kHz to 2MHz External Clock
  • Internal Compensation
  • Latch-off OCP Protection and Thermal Shutdown
  • Output Adjustable from 0.8V
  • Available in a QFN14 (3mmx4mm) Package


  • fsw (max) (kHz)500
  • Vin (min) (V)4.5
  • Vin (max) (V)24
  • Iout (max) (A)5
  • Isw Limit (typ) (A)7
  • Max Duty Cycle (%)0.9
  • Vfb (typ) (V)0.805
  • Iq (typ) (mA)1
  • Regulated Outputs1
  • Vout (min) (V)0.805
  • GradeCatalog
  • PackageQFN-14 (3x4)
  • Common FeaturesLight-Load Efficiency, Power Good, Synchronous Rectification
  • Special FeaturesExternal Frequency Sync