SY21113B1ADC - High Efficiency, 3.0A, 18V Input Synchronous Step Down Regulator


  • Low RDS(ON) for Internal Switches (Top/Bottom): 80mΩ/40mΩ
  • 4.5~18V Input Voltage Range
  • 3A Output Current Capability
  • 1.4MHz Switching Frequency Minimize the External Components
  • Stable with 10µF COUT and 0.68µH Inductor
  • Instant PWM Architecture to Achieve Fast Transient Responses
  • Internal Soft-start Limits the Inrush Current
  • Forced PWM Operation
  • Cycle-by-cycle Peak/Valley Current Limitation
  • Hic-cup Mode Output Short Circuit Protection
  • Thermal Shutdown with Auto Recovery
  • Output Auto Discharge Function
  • Compact Package: TSOT23-6

Typical Application


The SY21113B1 is a high efficiency, 1.4MHz synchronous step-down DC/DC regulator capable of delivering up to 3A load current. It can operate over a wide input voltage range from 4.5V to 18V and integrate main switch and synchronous switch with very low RDS(ON) to minimize the conduction loss.

The SY21113B1 adopts the instant PWM architecture to achieve fast transient responses for high step down applications. In addition, it operates at pseudo-constant frequency of 1.4MHz to minimize the size of the inductor and the capacitor.


  • Set Top Box
  • Portable TV
  • DSL Modem
  • LCD TV
  • IP CAM
  • Networking