The R1224N 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. R1224N 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.
The R1224N Series are low supply current CMOS-based PWM/VFM step-down DC/DC controllers designed to be configured using a power transistor, inductor, diode, and capacitor. The series features an automatic switching mechanism that alternates between PWM and VFM control modes to maintain high efficiency across smaller output current ranges.
| Supply Current (Ipp1) | Typ. 20uA (E, F, L, M Versions), Typ. 30uA (G Version), Typ. 40uA (H Version) |
|---|---|
| Output Voltage Accuracy | +/- 2% |
| Oscillator Frequency (fosc) | 180kHz, 300kHz, 500kHz |
| Oscillator Maximum Duty Cycle (Mexduty) | Min. 100% |
| Input Voltage Range (Vin) | 2.3V to 18.5V |
| UVLO Detect Voltage (Vuvio) | Typ. 2.0V |
| Output Voltage Range (Vour) | 1.2V to 6.0V |
| Soft Start Time (tsar) | Typ. 10ms |
It is used as a power source for hand-held communication equipment, cameras, VCRs, battery-powered equipment, and home appliances.
The device is available in a SOT-23-5 package.