R1218 Series
PWM Step-up DC/DC Converter for White LED

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  • Description

    The R1218 Series are CMOS-based PWM step-up DC/DC converters, which are optimized to drive white LEDs with constant current. R1218 includes an under-voltage lockout circuit (UVLO), over-voltage protection circuit (OVP). By simply using an inductor, a resistor, and a capacitor (, a diode) as external components, white LEDs can be driven with constant current efficiency. R1218Nxx1A for 2 to 4 lights contains an internal diode while R1218Nxx2A 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.

  • Spec
    Input Voltage Range 1.8 V to 5.5 V (6.5 V)
    Operating Temperature Range -40°C to 85°C (125°C)
    Supply Current Typ. 500 µA
    Standby Current Typ. 0 µA
    Output Voltage Range Externally Adjustable: Max. 30 V
    Feedback Voltage Typ. 0.2 V
    Feedback Voltage Accuracy ±10 mV
    Oscillator Frequency Typ. 1.2 MHz
    Maximum Duty Cycle Typ. 91 to 92%
    Package SOT-23-6

    Protections / Functions

    TSD ILX OCP OVP UVLO OVLO Reverse Shutdown Soft Start SSCG PGOOD Auto Discharge Anti-ringing Sequencing Max Duty Ext. Phase LED Adjust
  • Technical
    • R1218N041A Typical Application

      R1218N041A Typical Application

    • R1218N072A Typical Application

      R1218N072A Typical Application

    • R1218N041A Efficiency vs. Output Current

      R1218N041A Efficiency vs. Output Current

    • Related Links

      • Prime Designer

        Online Design Tool

        Registration to myNISD is required to use some of the functions, such as simulations.

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  • Quality &
    • Refer to the datasheets for the details on the product.
    • The package file or the datasheet includes package dimensions, taping specifications, taping reels dimensions, power dissipations, and recommended land pattern.

Download Datasheet

Functional Description

TSD Thermal Shutdown Function
ILX LX Current Limit Function
OCP Overcurrent Protection
OVP Overvoltage Protection
UVLO Undervoltage Lockout Protection
OVLO Overvoltage Lockout Protection
Reverse Reverse Current Protection Circuit
Shutdown Shutdown Function
Soft Start Soft Start Function
SSCG Spread Spectrum Clock Generator Function
PGOOD Power Good Output
Auto Discharge Auto Discharge Function
Anti-ringing Anti-ringing Switch Function
Sequencing Start-up Sequencing Control
Max Duty Maximum Duty Cycle
Ext. Phase Externally Adjustable Phase Compensation
LED Adjust LED High-speed Dimming Control

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