Nisshinbo Micro Devices Inc. R1243S001E-E2-FE

The R1243x is a CMOS-based step-down DC/DC converter with internal Nch high-side Tr. (0.175 Ω), 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(PL)2527-10 packages that can achieve high density mounting.

• Operating Voltage Range: 4.5 V to 30 V
• Standby Current: Max. 10 μA (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
• Output Current: Max. 2 A
• Peak Current Limiting: Typ. 3.8 A
• Internal Nch MOSFET Driver: Typ. 175 mΩ
• 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 kHz
• Internal Soft-start Time: Typ. 0.4 ms, TSS = Open
• External Soft-start Time: Typ. 12 ms, CSS = 0.1 μF
• Flag Output: Typ. 0.25 ms, FLG “OFF” delay time
• UVLO Released Voltage: Typ. 4.0 V
• Thermal Shutdown: Typ. 160°C, Hysteresis = 35°C
• Package: HSOP-8E, DFN(PL)2527-10

• Digital Home Appliances
• Hand-held Communication Equipment: Cameras, VCRs, Camcorders
• Battery-powered Equipment
• Battery Charger