ELECTRONICS: Linear Technology Corp.’s LT3492, a 2.1MHz dc/dc converter is designed to operate as a three-channel constant current LED driver. Each of the LT3492’s three channels can drive up to 10, 300 mA LEDs in series, enabling it to drive up to 30 x 300 mA LEDs at efficiencies up to 96 percent. All three channels are operated by an independent True Color PWMTM signal, enabling each to be dimmed independently to ratios as high as 3,000:1. A fixed frequency, current mode architecture ensures stable operation over a wide range of supply and output voltages. A frequency adjust pin enables the user to program the frequency between 330 kHz and 2.1 MHz to optimize efficiency while minimizing external component size. The LT3492’s thermally enhanced 4 mm x 5 mm QFN (or thermally enhanced TSSOP) package provides a highly compact solution footprint for up to 50W LED applications.
The LT3492 senses output current at the high side of the LED, enabling buck, buck-boost or boost configurations. With an external sense resistor, the user can program the output current range of each channel. Each of the three independent driver channels utilizes an internal 600 mA, 60V NPN switch and has a built-in gate driver for PMOS disconnect. Other features include open LED protection and thermal limiting.
The LT3492EUFD is available in a thermally enhanced 28-lead 4 mm x 5 mm QFN package, and the LT3492EFE is available in a thermally enhanced TSSOP-28 package. Pricing starts at $3.70 and $3.85 each, respectively in 1,000 piece quantities. Industrial grade versions, the LT3492IUFD and LT3492IFE, are tested and guaranteed to operate from -40 to 125C operating junction temperature and are priced at $4.35 and $4.53 each, respectively in 1,000 piece quantities. All versions are available from stock.
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