45V, 1.5A LED driver
27 April 2010
Linear Technology’s H-grade version of the LT3517 is a high side current sense DC/DC converter.
It has been designed to drive high current LEDs at constant current and its 3V to 30V input voltage range with transient protection to 40V makes it suitable for many applications; including automotive.
The H-grade version operates with a junction temperature up to 150˚C, compared to the E and I grade versions’ 125˚C maximum junction temperature. All electrical specifications are identical for the E, I and H-grade versions. The H-grade parts are tested and guaranteed to the maximum junction temperature of 150˚C.
The LT3517 can drive up to four 300mA white LEDs from a nominal 12V input, making it ideal for applications such as automotive display backlighting. The LT3517 senses output current at the high side of the LED, enabling buck, buck-boost or boost configurations. The device delivers efficiencies up to 90% in boost mode from a 4mm x 4mm QFN package. The LT3517 offers True Color PWM dimming which ensures constant LED colour with dimming ranges of up to 5000:1. For less demanding dimming requirements, the CTRL pin can be used to provide 10:1 analogue dimming. Its fixed frequency, current mode architecture offers stable operation over a wide range of supply and output voltages. A frequency adjust pin enables the user to programme the frequency between 250kHz and 2.5MHz to optimise efficiency while minimising external component size.
The LT3517HUF is available from stock in a 16-pin QFN package.
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