LM3501TLX-25

• Synchronous rectification is required, high efficiency, and no external Schottky diode is required
• Use small surface mount components
• Can drive 2-5 series white LEDs (possible functions with lower V F indicators)
• Input voltage range of 2.7V to 7V
• True shutdown isolation with no leakage current from LEDs
• LED current control for DC voltage
• Enter the undervoltage lock
• Internal Output Overvoltage Protection (OVP) Circuit, LM3501-16 Required, No External Zener Diode Required: 15.5V OVP; LM3501-21: 20.5V OVP.
• All that is required for input and output is a very small 16V (LM3501-16) or 25V (LM3501-21) ceramic capacitor
• Thermal shutdown
• 0.1μA shutdown current
• Low-profile micro SMD package with a small 8-bump ball

illustrate

The LM3501 is a fixed-frequency step-up DC/DC converter ideal for driving white LED displays, backlighting, and other lighting functions. With fully integrated synchronous switching (no external Schottky diode required) and low feedback voltage (515 mV), the power efficiency of the LM3501 circuit is optimized for lighting applications in wireless mobile phones and other portable products (powered by a single lithium-ion battery or a 3-NiMH battery). The LM3501 operates a fixed 1 MHz switching frequency. The LM3501 ceramic input and output capacitors provide a small, low-noise, low-cost solution when used together.

Two LM3501 options are available with different output voltage capabilities. The LM3501-21 has a maximum output voltage of 21V and is usually suitable for driving 4 or 5 white LEDs in series. The LM3501-16 has a maximum output voltage of 16V and is typically suitable for driving 3 or 4 white LEDs in series (the maximum number of LEDs in series depends on the forward voltage of the LEDs). If the main white LED network should be disconnected, the LM3501 employs the output of an internal protection circuit to prevent damaging overvoltage events.

A single external resistor is used to set the maximum LED current for the LED driver application. The LED current can be easily adjusted to the analog control voltage on different control pins, or by using a pulse width modulation (PWM) signal to shut off the pin. The LM3501 completely shuts down, disconnects the output input, creates complete isolation, and prevents any leakage current from trickling from the LED.

apply

• LCD bias power supply
• White LED backlight
• Handheld device
• Digital camera
• Portable application