R1243x Series 30 V Input 2 A Buck DC/DC Converter No.EA-206-210519 OUTLINE The R1243x is a CMOS-based step-down DC/DC converter with internal Nch high-side Tr. (0.175 ), which can provide the maximum 2 A output current. Internally, the R1243x consists of an oscillator, a PWM control circuit, a reference voltage unit, an error amplifier, phase compensation circuits, a slope circuit, a soft-start circuit, protection circuits, internal voltage regulators and a switch for bootstrap circuit. A step-down DC/DC converter can be configured by only adding an inductor, resistors, a diode and capacitors to the R1243x. The R1243x is a current mode operating type DC/DC converter that does not require external current sense resistor. It has high-speed response time and is high efficiency and compatible with ceramic capacitors. The oscillator frequency of the R1243x001A/B/E is fixed to 1000 kHz. The oscillator frequency of the R1243x001C/D is fixed 330 kHz. The R1243x has a cycle-by-cycle peak current limit function, a short protection function, a thermal shutdown function and an UVLO as protection features. The R1243x001A/C/E has a latch protection with 2 ms delay time, the R1243x001B/D has a fold-back protection that keep operating during short condition with lower operating frequency and limiting the LX current. The R1243x has a built-in soft-start time (Typ. 0.4 ms). In addition to this, the soft-start time is adjustable by adding an external capacitor. The R1243x has the FLG pin, which mainly monitors the FB pin voltage and gives a flag output by the Nch open drain if the abnormal condition is detected. The R1243x is offered in 8-pin HSOP-8E and 10-pin DFN(PLP)2527-10 packages that can achieve high density mounting. FEATURES Operating Voltage Range ...................................... 4.5 V to 30 V Standby Current..................................................... Max. 10 A (VIN = 30 V, CE = L) Supply Current ....................................................... Typ. 0.7 mA (VIN = 30 V, VFB = 1.0 V) Output Voltage Range ........................................... 0.8 V to 18 V, Adjustable with external resistors Feedback Voltage .................................................. 0.5 V with 1.4% accuracy (1) Output Current ....................................................... Max. 2 A Peak Current Limiting ............................................ Typ. 3.8 A Internal Nch MOSFET Driver ................................. Typ. 175 m Maximum Duty Cycle ............................................. Min. 85% Oscillator Frequency .............................................. R1243x001A/B/E: 1000 kHz, R1243x001C/D: 330 kHz Latch Type Protection ............................................ R1243x001A/C: Typ. 2 ms, R1243x001E: 0.08 ms Fold-back Type Protection ..................................... R1243x001B: 250 kHz, R1243x001D: 82.5 kH Internal Soft-start Time .......................................... Typ. 0.4 ms, TSS = Open External Soft-start Time ......................................... Typ. 12 ms, CSS = 0.1 F Flag Output ............................................................ Typ. 0.25 ms, FLG OFF delay time UVLO Released Voltage ........................................ Typ. 4.0 V Thermal Shutdown................................................. Typ. 160C, Hysteresis = 35C Package ............................................................... HSOP-8E, DFN(PLP)2527-10 (1) This is an approximate value, because output current depends on conditions and external parts. 1 R1243x No.EA-206-210519 APPLICATIONS Digital Home Appliances Hand-held Communication Equipment: Cameras, VCRs, Camcorders Battery-powered Equipment Battery Charger SELECTION GUIDE The package type, the oscillator frequency (Fixed: 1000 kHz, 330 kHz) and the short-circuit protection type (Latch, Fold-back) are user-selectable options. Selection Guide Product Name Package Quantity per Reel Pb Free Halogen Free R1243S001-E2-FE HSOP-8E 1,000 pcs Yes Yes R1243K001-TR DFN(PLP)2527-10 5,000 pcs Yes Yes : Specify the oscillator frequency and the short-circuit protection type. (A) Fixed Frequency: 1000 kHz, Latch Type (2 ms) (B) Fixed Frequency: 1000 kHz, Fold-back Type (C) Fixed Frequency: 330 kHz, Latch Type (2 ms) (D) Fixed Frequency: 330 kHz, Fold-back Type (E) Fixed Frequency: 1000 kHz, Latch Type (0.08 ms), only for HSOP-8E 2