APPLICATIONS
LM3501 Synchronous Step-up DC/DC Converter for White LED APPLICATIONS
GENERAL DESCRIPTION
When used with ceramic input and output capacitors, the LM3501 provides a small, low-noise, low-cost solution. Two LM3501 options are available with different output voltage capabilities. The LM3501-21 has a maximum output voltage of 21V and is typically suited for driving 4 or 5 white LEDs in series. The LM3501-16 has a maximum output voltage of 16V and is typically suited for driving 3 or 4 white LEDs in series (maximum number of series LEDs dependent on LED forward voltage). If the primary white LED network should be disconnected, the LM3501 uses internal protection circuitry on the output to prevent a destructive overvoltage event. A single external resistor is used to set the maximum LED current in LED-drive applications. The LED current can easily be adjusted by varying the analog control voltage on the control pin or by using a pulse width modulated (PWM) signal on the shutdown pin.
National Semiconductor
