Nisshinbo Micro Devices Inc. R1240K003B-TR

The R1240x is a CMOS-based Step-down DC/DC converter with internal Nch high side Tr. (0.35 Ω), which can provide the maximum 1.2 A output current. The ICs 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 boot strap circuit. The ICs can make up a StepDown DC/DC Converter with the following external components: an inductor, resistors, a diode, and capacitors. The R1240x is a current mode operating type DC/DC converter which does not require external current sense resistor, and it works high speed response time, high efficiency and compatible with ceramic capacitors. Oscillator frequency is internally set at 1.25 MHz. As a protection function, it has cycle by cycle peak current limit function, short protection function, thermal shutdown function and UVLO. There are two types for short protection, A version has latch protection function with 2 ms delay time, and B version has fold-back protection function that keep operating at short condition with lower operating frequency and limiting the Lx current.

• Operating Voltage: 4.5 V to 30 V
• Internal Nch MOSFET Driver: Typ. RON = 0.35 Ω
• Adjustable Output Voltage with External Resistor: 0.8 V to 15 V
• Feedback Voltage: 0.8 V ±1.5%
• Peak Current Limit Function: Typ. 2.0 A
• UVLO Function
• Operating Frequency: 1.25 MHz (Ver. B: 310 kHz, Fold-back Condition)
• Short Protection for Output: Ver. A: Latch with 2 ms delay or Ver. B: Fold-back
• Ceramic Capacitor Compatible
• Stand-by Function: Typ. 0 µA
• Package: SOT-23-6W, DFN(PLP)2527-10

• Digital Home Appliances: Digital TVs, DVD Players
• OA Equipment: Printers, Fax
• Hand-held Communication Equipment, Cameras, VCRs, Camcorders
• Battery-powered Equipment