R1224N

The R1224N Series are CMOS-based PWM step-down DC/DC Converter controllers with low supply current.Each of these ICs consists of an oscillator, a PWM control circuit, a reference voltage unit, an error amplifier, a phase compensation circuit, a soft-start circuit, a protection circuit, a PWM/VFM alternative circuit, a chip enable circuit, resistors for output voltage detect, and input voltage detect circuit. R1224N, A low ripple, high efficiency step-down DC/DC converter can be easily composed of this IC with only several external components, or a power-transistor, an inductor, a diode and capacitors. Output Voltage is fixed or can be adjusted with external resistors (Adjustable types are without PWM/VFM alternative circuit).

Features of the R1224N are:(1)range of input voltage:2.3V~18.5V; (2)built-in soft-start function and protection function (reset type protection); (3)three options of oscillator frequency:180kHz, 300kHz, 500kHz; (4)high efficiency:typ. 90%; (5)output voltage:stepwise setting with a step of O.1V in the range of 1.2V to 6.0V as fixed voltage type. reference voltage of adjustable type is 1.0V; (6)standby current:typ. 0.0A; (7)high accuracy output voltage:±2.0%; (8)low temperature-drift coefficient of output voltage:Typ.±100ppm/.

The absolute maximum ratings of the R1224N can be summarized as:(1)Vin supply voltage:20V;(2)storage temperature range:-55 to +125;(3)operating temperature range:-40 to +85 ;(4)power dissipation:250mW;(5)EXT pin inductor drive output current:±50mA.Protection circuit may work if the maximum duty cycle continue for the time defined in the electrical characteristics.Once after stopping the output voltage, output will restart with soft-start operation.If the difference between input voltage and output voltage is small, the protection circuit may work.The performance of power source circuits using these ICs extremely depends upon the peripheral circuits.Pay attention in the selection of the peripheral circuits. In particular, design the peripheral circuits in a way that the values such as voltage, current, and power of each component, PCB patterns and the IC do not exceed their respected rated values.