Dual step-down DC/DC operates from 3.4V to 42V inputs

May 18, 2015 // By Graham Prophet
LT8616 is a 42V input capable, high efficiency dual synchronous monolithic step-down switching regulator. Its dual channel design 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 6.5 µA (both channels enabled) in no-load standby conditions, making it suitable for always-on systems. Switching frequency can be programmed from 200 kHz to 3 MHz and is synchronisable throughout this range.

LT8616’s 35 ns minimum on-time enables 16VIN to 1.8VOUT step-down conversions, while switching at 2 MHz helps designers avoid critical noise-sensitive frequency bands, such as AM radio, while having a very compact solution footprint. Its 3.4V to 42V input voltage range suits it 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 400 mV (at 1A) under all conditions. The LT8616’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 uses 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 degrees out-of-phase to reduce output ripple. Each channel 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 15 mVP-P. LT8616's current-mode topology provides fast transient response and 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°C to 125°C (junction) for the extended (E) and industrial (I) grades and a high temperature (H) grade of -40°C to 150°C. Pricing starts at $4.15 (1000).

Linear Technology; www.linear.com/product/LT8616