• Low R_DS(ON) for Internal Switches (Top/Bottom): 17/7.5mΩ
• Wide Input Voltage Range: 5.5~24V
• Integrated Bypass Switch: 1.5Ω
• Instant PWM Architecture to Achieve Fast Transient Responses
• Internal Soft-start Limits the Inrush Current
• Pseudo-constant Frequency: 600kHz
• Fixed 5.15V Output Voltage
• 11A Output Current Capability
• 100mA LDO Current Capability
• ±1.5% Internal Reference Voltage
• PFM/USM Selectable Light Load Operation Mode
• Power Good Indicator
• Output Discharge Function
• Cycle-by-cycle Valley and Peak Current Protection for Buck
• Latch-off Mode Output Under Voltage Protection for Buck
• Latch-off Mode Output Over Voltage Protection for Buck
• Latch-off Mode Over Temperature Protection for Buck
• Auto-recovery Mode Output Under Voltage Protection for LDO
• Auto-recovery Mode Over Temperature Protection for LDO
• Input Under Voltage Lock-out(UVLO)
• RoHS Compliant and Halogen Free
• Compact package: QFN3×4-13

The SY21249C1 high-efficiency synchronous step-down DC/DC regulator is capable of delivering 11A current over a wide input voltage range of 5.5V to 24V. To minimize conduction loss, it integrates a main switch and a synchronous switch with very low R_DS(ON). It operates at a pseudoconstant frequency of 600kHz under heavy load conditions to minimize inductor and capacitor sizes. 

The SY21249C1 also provides a fixed 5V LDO with 100mA current capability, which can be used to power external peripherals. Under light load conditions, the LDO can be switched over to the buck regulator output to reduce power loss.

Silergy’s constant on-time (COT) ripple-based control strategy 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, even with low-ESR ceramic capacitors.

The SY21249C1 offers protection against multiple conditions, including cycle-by-cycle current limit, input undervoltage lockout, output undervoltage and overvoltage protection, internal soft-start, and thermal shutdown.

The SY21249C1 is available in a compact QFN3mm×4mm-13 package.