Step-Up DC/DC Converter-Backlight LED Driver
■GENERAL DESCRIPTION
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 2.0 Ω 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.Step-Up DC/DC Converter-Backlight LED Driver
■GENERAL DESCRIPTION
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 PWMStep-Up DC/DC Converter-Backlight LED Driver
■GENERAL DESCRIPTION
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 2.0 Ω 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. 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 2.0 Ω 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.