The LM3501 is a fixed-frequency step-up DC/DC converter that is ideal for driving white LEDs for display backlighting and other lighting functions. With fully intergrated synchronous switching (no external schottky diode required) and a low feedback voltage (515 mV), power efficiency of the LM3501 circuit has been optimized for lighting applications in wireless phones and other portable products (single cell Li-Ion or 3-cell NiMH battery supplies). The LM3501 operates with a fixed 1 MHz switching frequency. When used with ceramic input and output capacitors, the LM3501 provides a small, low-noise, low-cost solution.
Features
Synchronous rectification, high efficiency and no external schottky diode required
Uses small surface mount components
Can drive 2-5 white LEDs in series (may function with more low VF LEDs)
2.7V to 7V input range
True shutdown isolation, no LED leakage current
DC voltage LED current control
Input undervoltage lockout
Internal output over-voltage protection (OVP) circuitry, with no external zener diode required LM3501-16: 15.5V OVP; LM3501-21: 20.5V OVP.
Requires only a small 16V (LM3501-16) or 25V (LM3501-21) ceramic capacitor at the input and output
