The R1224 Series are low supply current CMOS-based PWM/VFM step-down DC/DC controller with an external output transistor. By simply using a power transistor, an inductor, a diode, and a capacitor as external components, a high-efficiency step-down DC/DC converter can be easily configured. The PWM/VFM alternative circuit automatically switches to VFM control in the smaller output current range and provides high efficiency even in the smaller output current range. The version with fixed PWM control and adjustable output voltage with an external resistor is also available.
The reset type protection circuit embedded into the device limits output current by repeatedly triggering the soft start circuit when the oscillator maximum duty cycle continues for a predetermined period of time. When the oscillator maximum duty cycle ends, normal operation is resumed automatically. R1224 also includes an under-voltage lockout circuit (UVLO) that stops DC/DC operation and prevents malfunction when the supply voltage falls below the UVLO detect voltage and reduces supply current.
|Input Voltage Range (Maximum Rating)||2.3 V to 18.5 V (20.0 V)|
|Supply Current||Typ. 20 µA (R1224Nxx2E/F/M/L, R1224N102M)
Typ. 30 µA (R1224Nxx2G, R1224N102G)
Typ. 40 µA (R1224Nxx2H, R1224N102H)
|Standby Current||Typ. 0 µA|
|Output Voltage Range||1.2 V to 6.0 V (0.1 V steps; R1224Nxx2x)
1.0 V to VIN (R1224N102x)
|Output Voltage Accuracy||±2.0%|
|Oscillator Frequency||Typ. 180 kHz (R1224Nxx2L/M, R1224N102M)
Typ. 300 kHz (R1224Nxx2E/G, R1224N102G)
Typ. 500 kHz (R1224Nxx2F/H, R1224N102H)
|Reset Protection Circuit||Typ. 15 ms|
|Temperature-Drift Coefficient of Output Voltage||Typ. ±100 ppm/°C|
|Soft Start Time||Typ. 10 ms|
|Protection Function||Built-in Current Limit Circuit|
R1224N332E Efficiency vs. Output Current
|3||VOUT or VFB|
The output voltage, the oscillator frequency, the modulation method and the output voltage adjustment for the ICs can be selected at the user’s request.
|Product Name||Package||Quantity per Reel|