3-A buck-boost converter touts wide application

Milpitas, Calif.—Linear Technology promotes its LT3477 buck-boost DC/DC converter as one that's suited to a wide variety of jobs, including service as a high-current LED driver. In the latter application, the wide-input (2.5-25 volt), 3-amp device, with dual rail-to-rail current sense amplifiers, combines a traditional voltage feedback loop and two current feedback loops to operate as a constant-current and a constant-voltage source. Both inputs of its error amplifier are available to the user, allowing the LT3477 to be used as either a boost converter, SEPIC device, or an inverter. Configured as a buck-boost mode or buck-mode LED driver, it can operate efficiently even in environments where there's wide battery voltage fluctuations, such as in automotives. Its switching frequency can be programmed with a single resistor between 200 kHz and 3.5 MHz, enabling the designer to minimize external component sizes and avoid "noise critical" frequency bands in the system. A tiny low-profile inductor and ceramic capacitors keep solution footprints very compact while minimizing solution cost.

The LT3477, with its low-saturation (VCE_sat, 300 mV at 2.5 A) switch, operates at efficiencies of up to 91 percent. It features a programmable soft-start function to limit inductor current during start-up and inrush current protection to protect the LT3477 during shorts and line transients. Its low-profile (0.75 mm) QFN package is said to provide high thermal performance in a small footprint.

The device datasheet is available at www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1094,P11227,D7977. The 4-by-4 mm QFN-20 version, the LT3477EUF, and the TSSOP-16E version, the LT3477EFE, are available from stock. Pricing for the LT3477EUF starts at $3.15 each and $3.30 each for the LT3477EFE in 1k-piece quantities.

Linear Technology, 1-800-4LINEAR, www.linear.com