R1225N Series 18.5V Input PWM/VFM Step-down DC/DC Controller
The R1225N Series are low supply current CMOS-based PWM/VFM controlled step-down DC/DC controllers featuring an external output transistor. By utilizing simple external components such as a power transistor, inductor, diode, and capacitor, users can easily configure a high-efficiency step-down converter. The series includes both PWM/VFM alternative circuits that switch to VFM control for small output currents and versions with fixed PWM control.
| Supply Current (Ipp1) | Typ. 20uA (A, B, J, K Versions), Typ. 30uA (C Version), Typ. 40uA (D Version) |
|---|---|
| Oscillator Frequency | 180kHz, 300kHz, 500kHz, or 40kHz |
| Oscillator Maximum Duty Cycle | Min. 100% |
| Standby Current | Max. 0.5nA |
| UVLO Detect Voltage | Typ. 2.0V to 3.3V |
| Soft Start Time | Typ. 10ms |
| Output Voltage Range | .2V to 6.0V (internally fixed) |
| Output Voltage Accuracy | +/- 2% |
| Latch Type Protection Circuit Delay Time | Typ. 20ms |
| Package | SOT-23-6W |
The device requires a power transistor, an inductor, a diode, and a capacitor as external components.
It automatically switches to VFM control when operating in the smaller output current range to provide high efficiency.
It latches the power MOS in the "OFF" state if the oscillator maximum duty cycle continues for a predetermined period.