描述 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.

特性 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；

應(yīng)用 Application

? White LED Backlight for portable equipment

簡(jiǎn)介

R1218屬于集成電路（IC）的穩(wěn)壓器-DC-DC開(kāi)關(guān)穩(wěn)壓器。由制造生產(chǎn)的R1218穩(wěn)壓器 - DC-DC 開(kāi)關(guān)穩(wěn)壓器DC-DC 開(kāi)關(guān)穩(wěn)壓器 PMIC（電源管理集成電路）產(chǎn)品族中的產(chǎn)品是元器件級(jí)設(shè)備，用于需要穩(wěn)定 DC 輸入電壓和/或?qū)⑵滢D(zhuǎn)換為不同幅度的輸出電壓的應(yīng)用。這些器件與稱為“控制器”PMIC 的類似產(chǎn)品的區(qū)別在于集成了主開(kāi)關(guān)元件，設(shè)備提供的電力會(huì)通過(guò)該元件。