SY21240DRAC - High Efficiency Fast Response, 9A, 28V Input Synchronous Step Down Regulator with VDDQ LDO


  • Low RDS(ON) for Internal Switches of the Regulator (Top/Bottom): 27/9 mΩ
  • 4~24V Input Voltage Range
  • Compatible for LPDDR4X Application
  • Instant PWM Architecture to Achieve Fast Transient Responses
  • Internal 450μs Soft-start Limits the Inrush Current
  • 600kHz Pseudo-constant Switching Frequency
  • PFM/USM Selectable Light Load Operation Mode
  • ±1.0% 0.6V VDD2 Reference
  • 9A Continuous/12A Peak Output Current Capability of the VDD2 Regulator
  • Fixed 0.61V VDDQ Reference
  • ±1A Source/Sink Current Capability of the VDDQ LDO
  • VDD2 and VDDQ Power Good Indicator
  • Support VDDQ LDO High-Z in S3
  • Output Discharge Function for Both VDD2 and VDDQ in S4/S5
  • Guarantee VDD2 200mV Higher Than VDDQ at Any Operation Condition
  • Cycle-by-cycle Valley and Peak Current Limit Protection for VDD2
  • Latch-off Mode Output Under Voltage Protection for VDD2
  • Latch-off Mode Output Over Voltage Protection for VDD2
  • Latch-off Mode Over Temperature Protection for VDD2
  • Input UVLO and Bias UVLO
  • RoHS Compliant and Halogen Free
  • Compact package: QFN3×3-20

Typical Application


The SY21240D provides a complete power supply with the highest density for DDR3, DDR3L, LPDDR3 and DDR4 memory. It develops one high efficiency synchronous step-down DC/DC regulator VDD2 capable of delivering 9A continuous/12A peak current and one sink/source VDDQ LDO capable of delivering ±1A current. In addition, it operates at 600kHz pseudo constant frequency under continuous conduction mode. The integrated low RDS(ON) switches minimize the conduction loss.

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.

The SY21240D operates over a wide input voltage range from 4V to 24V. 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.


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