The TS1518 is a step-up DC-DC converter; operates as current source to drive up to 6 white LEDs(VIN at 3.0V) or 8 LEDs(VIN at 3.5V) or 9 LEDs(VIN at 3.5V) in series. Series connecting of the LEDs provides identical LED currents resulting in uniform brightness and eliminating the need for ballast resistors. The light intensity of these LEDs is proportional to the current passing through them. The TS1518 switches at a fixed frequency of ~930KHz, allowing the use of tiny, low profile inductors and capacitors to minimize footprint and cost in space consideration applications for cellular phone backlighting or other hand held equipment. The TS1518 can drive up to 9 white LEDs from a single LiIon battery. The wide input voltage range from 2.7V to 7V is ideal for portable with higher conversion efficiency. To control LED brightness, the LED current can be pulsed by applying a PWM (pulse width modulated) signal with a frequency range of 100Hz to 1KHz to the CTRL pin. TS1518 has integrated Latched Over Voltage Protection that prevents damage to the device in case of a high impedance output due to faulty LED or open circuit caused by abnormal conditions.