Step-Up DC/DC Converter-LED Backlight Driver

The XC9133 series is a fixed frequency, constant current step-up DC/DC converter which is optimized for LED backlight applications in mobile phones, PDAs and digital cameras. Output voltage of up to 17.5V is possible so that four white LEDs can be driven in series.

Since the LED current is set by only one external resistor, all white LEDs placed in series can be turned on at the same time. The new DC/DC Converter is also able to drive a network of two parallel banks of three LEDs.

LED dimming is controlled by adjusting the duty cycle of a PWM signal (10kHz Max.) applied to the CE pin.

Efficiency is high with a 0.2V low feedback reference voltage ensuring the RLED losses are minimal. In addition, an internal MOSFET with a low RDSON of 2.4Ω is used. A low profile and small board area solution can be achieved using a chip inductor and a small ceramic output capacitor CL=0.22μF as a result of the high 1MHz switching frequency.

If white LEDs are opened or damaged, the detector built in the Lx pin causes the IC to stop oscillating, preventing excessive increase of the output voltage.


Input Voltage Range 2.5V~6.0V
Output Voltage Range Up to 17.5V externally set-up, Reference voltage 0.2V ±5.0%
Oscillation Frequency 1.0MHz±20%
On Resistance 2.4Ω
High Efficiency 85%, 3 white LEDs in series, VIN=3.6V,ILED=20mA
Control PWM Control
Stand-by Current ISTB=1.0μA(MAX.)
Load Capacitors 0.22μF,Ceramic
Lx Limit Current 360mA(TYP.)
Lx Overvoltage Limit 19V(TYP.)

Typical Application Circuit

Technical Document


Package Number of Pins Pcs/Reel Package Size(mm)
SOT-25 5 3,000 2.8 x 2.9 x 1.3

XC9133 Series Part Numbers

Part number Sample Lx Overvoltage Limit FB Voltage Oscillation Frequency Packages EDA Online Store
XC9133B02AMR-G Available 0.2V 1MHz SOT-25

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