Step up DC/DC Converter - Backlight LED Driver

The XC9116 series is a fixed frequency, constant current step-up DC/DC converter ideal for driving LEDs used in backlighting applications such as cellular phones, PDAs and digital cameras. Output voltage of up to 17.5V can be derived, therefore, four white LEDs in series can be driven. Since an LED current can be set by an external resistor when LEDs are in-series connection, all white LEDs can be turned on equably. A network of two parallel legs with three in each LED can be also driven. Luminance of the LEDs is controlled by changing the duty cycle of a PWM signal applied to the CE pin. Efficiency is high with the low feedback reference voltage ensuring the RLED losses are minimal. In addition, an internal MOSFET with an RDSON of 2.0Ω is used. A low profile and small board area solution can be achieved using a chip coil and an ultra small ceramic output capacitor (CL) of 0.22μF as a result of the high 1.0MHz switching frequency.

The 'B' type of XC9116 has an additional fault detection circuit. If the LEDs are disconnected or damaged, excess or run away output voltage is prevented by stopping the drive of the internal MOSFET.


Input Voltage Range 2.5V~6.0V
Output Voltage Range Up to 17.5V externally set-up,Reference voltage 0.2V±5.0%
Reference Voltage 0.2V±5.0%
Oscillation Frequency 1.0MHz±20%
On Resistance 2.0Ω
High Efficiency 86%(TypeB),84%(TypeD), (VIN=3.6V,ILED20mA when driving 3 white LEDs in series)
Control PWM Control
Stand-by Current ISTB=1.0μA(MAX.)
Load Capacitors 0.22μF, Ceramic
Lx Limit Current 325mA
Lx Overvoltage Limit XC9116 TypeB
No Lx Overvoltage Limit XC9116D Type

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
USP-6B 6 3,000 1.8 x 2.0 x 0.7

XC9116 Series Part Numbers

Part number Sample Lx Overvoltage Limit FB Voltage Oscillation Frequency Packages EDA Online Store


Available 0.2V 1MHz USP-6B


Available 0.2V 1MHz SOT-25


Not available 0.2V 1MHz USP-6B


Not available 0.2V 1MHz SOT-25

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