SY21153AAIC - High Efficiency Fast Response, 3A, 40V Input Synchronous Step Down Regulator


  • Low RDS(ON) for Internal Switches (Top/Bottom): 110/70 mΩ
  • 4.5-40V Input Voltage Range
  • Internal Compensation
  • Internal 1ms Soft-start Limits the Inrush Current
  • Adjustable Switching Frequency Range: 500kHz to 2.5MHz
  • 3A Output Current Capability
  • 1.5% 0.6V Reference
  • Low Quiescent Current
  • Cycle-by-cycle Peak Current Limitation
  • Short Circuit Protection
  • Thermal Shutdown and Auto Recovery
  • RoHS Compliant and Halogen Free
  • Compact Package: TSOT23-8

Typical Application


The SY21153A develops a high efficiency synchronous step-down DC/DC converter capable of delivering 3A load current. The SY21153A operates over a wide input voltage range from 4.5V to 40V and integrates main switch and synchronous switch with very low RDS(ON) to minimize the conduction loss.

The SY21153A adopts peak current control scheme. The switching frequency is adjustable from 500 kHz to 2.5MHz using an external resistor. The device also features ultra low quiescent operating to achieve high efficiency under light load. And the internal soft-start limits inrush current during power on.

SY21153A is available in TSOT23-8 package.


  • LCD-TV
  • SetTop Box
  • Notebook
  • Storage
  • High Power AP Router
  • Networking