Step-down switching regulator integrates current sensing

27th February 2015
Nat Bowers

The LT8613 is a 6A, 42V input capable synchronous step-down switching regulator with integrated current sensing which has been introduced by Linear Technology. Synchronous rectification delivers efficiency as high as 95%, Burst Mode operation keeps quiescent current under 3µA in no-load standby conditions and its 3.4-42V input voltage range makes it suited for automotive and industrial applications.

The device's 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, making it well suited 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 only 250mV at 3A under all conditions, enabling it to excel in scenarios such as automotive cold-crank. Furthermore, a fast minimum on-time of only 40ns enables 2MHz 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 high switching frequency keeps external inductors and capacitors small, providing a compact, thermally efficient footprint.

The LT8613 utilises 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 10mVP-P. Special design techniques and a new high speed process enable high efficiency over a wide input voltage range, and the 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 28-lead 3x6mm QFN package and is priced at $5.20 each in 1,000 unit quantities.. An industrial temperature version, the LT8613IUDE, is tested and guaranteed to operate from a -40 to +125°C operating junction temperature and is priced at $5.72 each in 1,000 unit quantities.

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