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R1218 Series
PWM Step-up DCDC Converter for White LED

Product Specifications

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.

FEATURES

Input Voltage Range (Maximum Rating) 1.8 V to 5.5 V (6.5 V)
Supply Current Typ. 500 µA
Standby Current Typ. 0 µA
Oscillator Frequency (PWM control) 1.2 MHz
Maximum Duty Cycle Typ. 91 to 92%
Feedback Voltage Typ. 0.2 V
UVLO Threshold Voltage Typ. 1.6 V (Hysteresis Typ. 0.1 V)
Lx Current limit Protection Typ. 700 mA
Over Voltage Protection (OVP) Threshold Typ. 9.5 V (R1218x021A)
Typ. 14.0 V (R1218x031A)
Typ. 18.5 V (R1218x041A)
Typ. 23.0 V (R1218x052A)
Typ. 27.5 V (R1218x062A)
Typ. 31.5 V (R1218x072A)
LED dimming control by external PWM signal (Frequency 200 Hz to 5 kHz) to CE pin
by feedback voltage and filtered PWM signal (high frequency)
Built-in Nch MOSFET and diode R1218xxx1A: Built-in 400 mA, 1.5 Ω, 20 V Nch MOSFET and diode
R1218xxx2A: Built-in 400 mA, 1.5 Ω, 33 V Nch MOSFET
Package SOT-23-6

APPLICATION INFORMATION

R1218N041A

R1218N072A

TYPICAL CHARACTERISTICS

R1218N041A Efficiency vs. Output Current

PIN DESCRIPTION

SOT-23-6

SOT-23-62.9 mm × 2.8 mm
1 CE
2 VOUT
3 VIN
4 Lx
5 GND
6 VFB

R1218 Series for Consumer

APPLICATIONS

  • White LED Backlight for portable equipment

SELECTION GUIDE

The OVP threshold and the built-in diode for the ICs can be selected at the user’s request.

Product Name   Package Quantity per Reel
R1218Nxxxx-TR-FE Consumter SOT-23-6 3,000
  • xxxx … The combination of the OVP threshold and with/without of built-in diode can be designated.
Code OVP Threshold Built-in Diode
021A 9.5V Yes
031A 14.0V Yes
041A 18.5V Yes
052A 23.0V No
062A 27.5V No
072A 31.5V No

DOCUMENT/CONTACT

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Package *1 Marking Reliability *2
SOT-23-6 R1218N R1218N (-FE)

*1: The package file includes package dimensions, taping specifications, taping reels dimensions, power dissipations, and land pattern (foot pattern).
*2: Reliability file includes a reliability test report and a reflow profile.

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