Wide Vin 4.5-24V, 6A, COT Synchronous Step-down Converter with Low Quiescent Current



The NB671LB is the low quiescent current version of NB671. It is a fully integrated high frequency synchronous rectified step-down switch mode converter, which offers very compact solutions to achieve 6A continuous output current and 9A peak current over a wide input supply range with excellent load and line regulation. The NB671LB operates at high efficiency over a wide output current load range. 
Constant-On-Time (COT) control mode provides fast transient response and eases loop stabilization.
Under voltage lockout is internally set as 4.2 V, An open drain power good signal indicates the output is within its nominal voltage range.
Full protection features include OCP, OVP, and thermal shut down. 
The converter requires minimum number of external components and is available in QFN16 (3mmx3mm) package.
The NB671LB is pin-to-pin compatible with NB671 with a NC pin changed to LP#, which is used to receive the power state command from the system. 



  • Wide 4.5V to 24V Operating Input Range
  • 6A Continuous Output Current
  • 9A Peak Output Current
  • 60μA Quiescent Current
  • Low RDS(ON) Internal Power MOSFETs
  • Proprietary Switching Loss Reduction Technique
  • 1% Reference Voltage
  • Internal Soft Start
  • Output Discharge
  • 500kHZ Switching Frequency
  • OCP, OVP, UVP Protection and Thermal Shutdown
  • Output Adjustable from 0.604V to 5.5V
  • Support 5V Output from 5.5V Input


  • fsw (max) (kHz)500
  • 最小输入电压4.5
  • Vin (max) (V)24
  • Iout (max) (A)6
  • Isw Limit (typ) (A)9
  • Max Duty Cycle (%)0.955
  • Vfb (typ) (V)0.604
  • Iq (typ) (mA)0.12
  • 额定输出1
  • Vout (max) (V)5.5
  • Vout (min) (V)0.604
  • GradeCatalog
  • PackageQFN-16 (3x3)
  • Control ModeCOT
  • Common FeaturesLight-Load Efficiency, Power Good, Synchronous Rectification
  • Special FeaturesOutput Discharge