The TS1520 is a step-up DC-DC converter; operates as current source to drive up to 18 white LEDs in parallel/series configuration. 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 TS1520 switches at a fixed frequency of 700KHz, 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 TS1520 can drive up to 18 white LEDs form 4.5V supply. The wide input voltage range from 2.7V to7V is ideal for portable (5V) applications 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 50KHz to the CTRL pin. TS1520 has integrated 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.