Integrated current sensing boosts performance of 42V, 6A output regulator

March 02, 2015 // By Graham Prophet
LT8613 is a 6A, 42V-input-capable synchronous step-down switching regulator with integrated current sensing. Synchronous rectification delivers efficiency of up to 95% while Burst Mode operation keeps quiescent current under 3 µA in no-load standby conditions.

Its 3.4V to 42V input voltage range makes it suitable for automotive and industrial applications. Its internal high efficiency switches deliver up to 6A of continuous output current to voltages as low as 0.97V. An internal current sense amplifier with monitor and control pins enable accurate input or output current regulation and limiting.

The LT8613’s Burst Mode operation offers ultralow quiescent current, for applications such as automotive “always-on” systems, which need to extend operating battery life. The LT8613’s unique design maintains a minimum dropout voltage of 250 mV at 3A under all conditions, enabling it to accommodate scenarios such as automotive cold-crank. Fast minimum on-time of 40 nsec enables 2 MHz constant frequency switching from a 16V input to a 1.5V output, enabling designers to optimise efficiency while avoiding critical noise-sensitive frequency bands. The LT8613’s 28-lead 3 x 6 mm QFN package and high switching frequency keeps external inductors and capacitors small, providing a compact, thermally efficient footprint.

The LT8613 employs internal top and bottom high efficiency power switches with the necessary boost diode, oscillator, control and logic circuitry integrated into a single die. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping output ripple below 10 mVp-p. LT8613’s current-mode topology enables fast transient response and excellent loop stability. Other features include internal compensation, a power good flag, output soft start/tracking and thermal protection.

The LT8613EUDE is packaged in a 3 x 6mm QFN package and is priced at $5.20. An industrial temperature version, the LT8613IUDE, is tested and guaranteed to operate from a -40°C to 125°C operating junction temperature and is priced at $5.72 (all 1000).

Linear Technology; www.linear.com/product/LT8613

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