Linear has introduced the LT3599, a 45V, 2.1MHz DC/DC boost mode converter that operates as a constant current LED driver that can drive up to 40 white LEDs.
According to reports, the LT3599 can drive up to 4 LED strings from a single 12V input, with up to 10 120mA white LEDs in series per string, while delivering up to 90% efficiency. Its multi-channel capability makes this device ideal for medium-sized TFT-LCD backlighting applications. The LT3599's 3.1V to 30V input voltage range is ideal for automotive, medical, and industrial applications. The device provides 1.5% LED current matching to ensure consistent display brightness. A dimming ratio of up to 3000:1 can be obtained by using True Color PWM dimming. Programmable 200kHz to 2.1MHz fixed frequency operation and current mode architecture provides stable operation over a wide supply and output voltage range while minimizing external component size.
In addition, the switching frequency can be synchronized to an external clock to improve noise immunity. The LT3599 uses a single 2A, 45V internal switch to provide a boost mode constant current source. However, even when VIN exceeds VOUT, the LT3599 will continue to regulate the LED current. The internal boost converter uses an adaptive feedback loop to regulate the output voltage slightly above the required LED voltage to ensure maximum efficiency. If any of the LED strings are open, it will continue to adjust the existing LED string and signal the OPENLED alarm pin. If higher current LEDs are required, multiple LED strings can be combined to drive up to two LED strings of 10 240mA LEDs. Other features include LED current derating based on junction temperature and/or LED temperature, and programmable overvoltage protection when all LED strings are disconnected.
The LT3599's thermally enhanced 5mm x 5mm QFN or TSSOP-28E package provides a highly compact solution footprint for LED backlighting applications.
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