• Low R_DS(ON) for Internal Switches (Top/Bottom): 38/19 mΩ
• Wide Input Voltage Range: 4.5~24V
• Integrated Bypass Switch: 1.2Ω
• Instant PWM Architecture to Achieve Fast Transient Responses
• Internal Soft-start Limits the Inrush Current
• Pseudo-constant Frequency: 600kHz
• Adjustable Output Voltage Application
• 6A Output Current Capability
• ±1% Internal Reference Voltage
• PFM/FCCM Selectable Light Load Operation Mode
• Power Good Indicator
• Output Discharge Function
• Cycle-by-cycle Valley and Peak Current Limit Protection
• Programmable Valley Current Limit Threshold by ILMT Pin
• Hic-cup Mode Output Under Voltage Protection
• Auto-recovery Mode Output Over Voltage Protection
• Auto-recovery Mode Over Temperature Protection
• Input UVLO
• RoHS Compliant and Halogen Free
• Compact Package: QFN2.5×2.5-16

The SY21138A high-efficiency synchronous step-down DC/DC regulator is capable of delivering 6A current over a wide input voltage range of 4.5V to 24V.

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.

Internal 38mΩ power and 19mΩ synchronous rectifier switches provide excellent efficiency over a range of applications, especially for low output voltages and low duty cycles. The SY21138A also integrates a bypass switch that allows the IC to be powered by an external DC source. The SY21138A 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.

Only the input and output capacitors, inductor, and feedback resistors need to be selected for the targeted application.

The SY21138A is available in a compact QFN2.5×2.5-16 package.