Ricoh R1218X Manuals

The R1218x Series are PWM control type step-up DC/DC converter ICs with low supply current.

The R1218x Series are CMOS-based PWM step-up DC/DC converters, which are optimized to drive white LEDs with constant current. R1218x includes an under-voltage lockout circuit (UVLO), over-voltage protection circuit (OVP). By simply using an inductor, (a diode), a resistor, and a capacitor as external components, white LEDs can be driven with constant current efficiently. R1218xxx1A for 2 to 4 lights contains an internal diode while R1218xxx2A for 5 to 7 lights requires an external diode. The LED current can be determined by the value of current setting resistor. The brightness of the LEDs can be adjusted by applying a PWM signal to the CE or VFB pin.