September 22, 2005 - National Semiconductor Corporation (NYSE:NSM) today introduced a tiny high-frequency white LED driver that features high-speed pulse width modulation (PWM) brightness control for handheld devices. The LM3519 drives up to four white LEDs with constant current for backlighting high-resolution displays in mobile phones, MP3 players, barcode scanners and other handheld portable devices.
The LM3519 is a highly efficient LED driver that delivers 20 mA to the LEDs with internal current regulation, eliminating the need for an external resistor. Brightness control is achieved by applying a PWM signal to the enable pin with frequencies up to 30 kHz to avoid audible noise.
The LM3519 features proprietary pulse frequency modulation regulation architecture with switching frequencies from 2 MHz to 8 MHz, minimizing inductor size.
Over-voltage protection circuitry and high-frequency operation allow the use of low-cost, small-output capacitors. During shutdown, the output is disconnected from the input in order to avoid leakage current path through the LEDs to ground.
Key Features for LM3519:
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Drives 2 to 4 LEDs at 20 mA
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Greater than 80% Efficiency
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Up to 8 MHz Switching Frequency
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Up to 30 kHz PWM Dimming Control
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Small External Components: 1 µH - 3.3 µH (typ. 2.2 µH) Inductor and 1 µF Output Capacitor
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True Shutdown Isolation
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Over-Voltage Protection
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Wide Input Voltage Range: 2.7V to 5.5V
Packaging, Pricing and Availability
Available now, the LM3519 is packaged in a tiny SOT23-6 and costs 70 cents in quantities of 1,000. Lead-free package options are also available. For more information on National’s switching regulators, visit power.national.com. For more information on the LM3519 or to order samples, visit http://www.national.com/pf/LM/LM3519. A selection of switching regulators is supported by National’s WEBENCH® online design tool. To explore these solutions, visit http://webench.national.com.
About National Semiconductor
National Semiconductor, the industry's premier analog company, creates high-value analog devices and subsystems. National's leading-edge products include power management circuits, display drivers, audio and operational amplifiers, communication interface products and data conversion solutions. National's key analog markets include wireless handsets, displays and a variety of broad electronics markets, including medical, automotive, industrial, and test and measurement applications. Headquartered in Santa Clara, California, National reported sales of $1.91 billion for fiscal 2005, which ended May 29, 2005. Additional company and product information is available at www.national.com.
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