Charge Pumps Drive Battery-Powered Devices
White LEDs are widely used today in handheld devices, such as cellular phones, as backlights for color liquid-crystal display (LCD) screens or to light up keypads. Colored LEDs, notably blue and green, are also used for such purposes and in addition are good indicators for reporting to the user an incoming call or a charging battery.
LED brightness is proportional to the amount of current flowing through the device. Also, the voltage must be high enough to turn the device on. The most popular batteries today are lithium-ion based, where the voltage is typically around 3.6 V but drops as the battery discharges. For these reasons, LEDs cannot be powered directly from the battery, and a regulated boost converter is needed. Regulated charge pump solutions are very popular especially in applications where the total output current is less than 100 mA, due to their simplicity and low cost.
LED brightness is proportional to the amount of current flowing through the device. Also, the voltage must be high enough to turn the device on. The most popular batteries today are lithium-ion based, where the voltage is typically around 3.6 V but drops as the battery discharges. For these reasons, LEDs cannot be powered directly from the battery, and a regulated boost converter is needed. Regulated charge pump solutions are very popular especially in applications where the total output current is less than 100 mA, due to their simplicity and low cost.
LED brightness is proportional to the amount of current flowing through the device. Also, the voltage must be high enough to turn the device on. The most popular batteries today are lithium-ion based, where the voltage is typically around 3.6 V but drops as the battery discharges. For these reasons, LEDs cannot be powered directly from the battery, and a regulated boost converter is needed. Regulated charge pump solutions are very popular especially in applications where the total output current is less than 100 mA, due to their simplicity and low cost.
