R1275S Series 30 V, 2 A, Synchronous PWM Step-down DC/DC Converter No. EA-370-201203 OVERVIEW The R1275S is a 36-V synchronous step-down DC/DC converter with built-in drivers. It is designed for industrial equipment, OA equipment and home electronics that require a 24-V input. It operates at a 2-MHz switching frequency, which allows to use a small inductor to ensure a high transient response and to maintain a high efficiency at heavy load condition. Using a spread spectrum clock generator, the EMI noise can be reduced. KEY BENEFITS Provides a high switching frequency at 2 MHz with an efficiency of 87%. Maintains the output voltage constant by reducing a switching frequency to the minimum 1/4 when an input-output voltage difference is small. Achieves the EMI noise reduction by using a spread spectrum clock generator. (Diffusion Rate: +8%). TYPICAL CHARACTERISTICS KEY SPECIFICATIONS Input Voltage Range (Maximum Ratings): 100 90 3.6 V to 30 V (36 V) 80 Start-up Voltage: 4.5 V 70 V =12V IN 60 Standby Current: Typ. 4 A 50 Output Voltage Range: 3.3 V to 5.0 V 40 Feedback Voltage: 0.64 V 1.0% 30 20 Adjustable Oscillator Frequency Using External 10 Resistors: 2 MHz 0 External Synchronous Clock Frequency: 0 500 1000 1500 2000 Iout mA 1.8 MHz to 2.2 MHz Spread Spectrum Clock Generator (SSCG): Efficiency (V = 5 V) OUT Diffusion Rate: Typ. +8% Minimum On-time: Typ. 70 ns Minimum Off-time: Typ. 120 ns OPTIONAL FUNCTIONS Duty-over: Min. 1/4 Soft-start Choose the optional functions from below. Thermal Shutdown: Tj = 160C Undervoltage Lockout (UVLO): V = 3.3 V (Typ.) CC Overvoltage Lockout (OVLO): VIN = 35 V (Typ.) Overcurrent Protection SSCG Overvoltage Detection (OVD): FB Pin Voltage (V ) +10% FB A Hiccup-type Disable LX Current Limiting: Typ. 3 A C Hiccup-type Enable High-side Driver On Resistance: Typ. 0.145 Low-side Driver On Resistance: Typ. 0.095 PACKAGE HSOP-18 5.2mm x 6.2mm x 1.45mm APPLICATIONS Portable Communication Equipment, Cameras, Video Digital Electronics: Digital TVs, DVD Players Cameras OA Equipment: Printers, Facsimiles Battery-powered Equipment 1 Efficiency % R1275S No. EA-370-201203 SELECTION GUIDE Selection Guide Product Name Package Quantity per Reel Pb Free Halogen Free HSOP-18 1,000 pcs Yes Yes R1275S003 -E2-FE Choose the optional functions from below. Overcurrent Protection SSCG A Hiccup-type Disable C Hiccup-type Enable BLOCK DIAGRAM R1275S Block Diagram 2