Step-down switching regulator is 95% efficient

12th May 2015
Siobhan O'Gorman


A 42V input capable, high efficiency, dual synchronous, monolithic, step-down switching regulator has been introduced by Linear Technology. Featuring a dual channel design, the LT8616 delivers independent 2.5A and 1.5A continuous current to outputs as low as 0.8V.

A dual channel synchronous rectification topology delivers up to 95% efficiency while Burst Mode operation keeps quiescent current under 6.5µA in no-load standby conditions, making the device suitable for always-on systems. Switching frequency can be programmed from 200kHz to 3MHz and is synchronisable throughout this range.

The regulator’s 35ns minimum on-time enables 16VIN to 1.8VOUT step-down conversions, while switching at 2MHz helps designers avoid critical noise-sensitive frequency bands, such as AM radio. The device’s 3.4 to 42V input voltage range makes it suitable for automotive applications which must regulate through cold-crank and stop-start scenarios with minimum input voltages as low as 3.4V and load dump transients in excess of 40V. Each channel of the LT8616 maintains a minimum dropout voltage of only 400mV under all conditions, enabling it to excel in scenarios such as automotive cold-crank. The regulator’s 28-lead thermally enhanced TSSOP package and high switching frequency keeps external inductors and capacitors small, providing a compact, thermally efficient footprint.

The LT8616 utilises dual internal top and bottom high efficiency power switches with the necessary boost diodes, oscillator, control and logic circuitry integrated into a single die. Each channel switches 180° out-of-phase to reduce output ripple and has a separate input for added design flexibility. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping output ripple below 15mVP-P. Unique design techniques and a high speed process enable high efficiency over a wide input voltage range, while the current-mode topology provides fast transient response and outstanding loop stability. Other features include internal compensation, power good flags, output soft-start/tracking and thermal protection.

The LT8616 is available in a thermally enhanced 28-lead TSSOP package. Three temperature grades are available, with operation from –40 to 125°C for the extended and industrial grades and –40 to 150°C for the high temperature grade. The 1,000 piece price starts at $4.40.

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