SY21144RAC - High Efficiency Fast Response 4A, 23V Input Synchronous Step Down Regulator


  • Low RDS(ON) for Internal Switches (Top/Bottom): 85/35mΩ
  • Wide Input Voltage range: 4-23V
  • Instant PWM Architecture to Achieve Fast Transient Responses
  • Internal 1.2ms Soft-start Limits the Inrush Current
  • Pseudo-constant Frequency: 600kHz
  • 4A Output Current Capability
  • ±1% Internal Reference Voltage
  • PFM/FCCM Selectable Light Load Operation mode
  • Optional Bypass Input
  • Power Good Indicator
  • Output Discharge Function
  • Output Current Limit Protection
  • Hiccup Mode Output Short Circuit Protection
  • Output Under Voltage Protection
  • Output Over Voltage Protection
  • Programmable Bottom FET Current Limit
  • Input Under Voltage Lock-out(UVLO)
  • Over Temperature Protection With Auto Recovery
  • RoHS Compliant and Halogen Free
  • Compact Package: QFN3×3-20

Typical Application


The SY21144 develops a high efficiency synchronous step-down DC/DC regulator capable of delivering 4A current over a wide input voltage range of 4V to 23V.

Silergy’s proprietary Instant-PWM™ fast-response, constant-on-time (COT) PWM control method supports high input/output voltage ratios (low duty cycles), and fast transient response while maintaining a near constant operating frequency over line, load and output voltage ranges. This control method provides stable operation without complex compensation and even with low ESR ceramic capacitors.

Internal 85mΩ power and 35mΩ synchronous rectifier switches provide excellent efficiency over a range of applications, especially for low output voltages and low duty cycles. Cycle-by-cycle current limit, input under voltage lock-out, internal soft-start, output under voltage protection and over voltage protection, and thermal shutdown provide safe operation in all operating conditions. The SY21144 is available in a compact QFN3×3-20 package.


  • LCD-TV/Net-TV/3DTV
  • Set Top Box
  • Notebook
  • High Power AP