R1244N001B-TR-FE

R1244N001B is a DC/DC converter with a built-in switch based on CMOS technology. The on-resistance of the built-in high-side switch is 0.35Ω (typical), capable of delivering a maximum current of 1.2A. This IC consists of an oscillator circuit, PWM control circuit, reference voltage source, error amplifier, phase compensation circuit, slope circuit, soft-start circuit, protection circuit, internal voltage regulator, and switch. External components include an inductor, resistors, a diode, and capacitors — all together forming a complete step-down DC/DC converter. Since R1244N001B operates in current limiting mode without requiring a sense resistor, it achieves high-speed, high-efficiency operation. Ceramic capacitors are recommended for the output capacitor. The switching frequency is internally fixed at 1.25MHz. As protection features, the IC provides cycle-by-cycle peak current limiting, a foldback function that reduces the switching frequency to 1/4 of the normal frequency during output short-circuit conditions, thermal shutdown, and undervoltage lockout (UVLO).

Applications

• Digital TVs, DVD players, and other digital home appliances
• Printers, fax machines, and other office automation equipment
• Constant voltage source for portable communication devices, cameras, and camcorders
• Constant voltage source for battery-powered equipment

Key features

• Operating voltage range: 4.5V~30V
• Built-in N-type driver, typical R_ON = 0.35Ω
• Output voltage externally adjustable via resistor, settable from 0.8V~15V
• Feedback voltage 0.8V±1.5%
• Peak current limit, typical value 2.0A
• Under-voltage lockout (UVLO) function
• Switching frequency 1.25MHz (310kHz during foldback operation)
• Ceramic capacitors applicable as input/output capacitors
• Standby current, typical value 0μA
• Package: SOT-23-6W