Triple monolithic synchronous buck converter works from 3-42V

26th February 2018

Analog Devices

Alice Matthews

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Datasheet

A 42V input capable, high efficiency quad output monolithic switching regulator has been announced by Analog Devices. The Power by Linear LT8603's flexible design combines a boost controller with two high voltage 2.5 and 1.5A synchronous step-down channels and a lower voltage 1.8A synchronous step-down channel to provide four independent outputs.

The LT8603 can be configured with the boost controller to supply the input of the buck converters, enabling it to deliver three precisely regulated outputs. This is the case even when the input falls significantly below the regulated output voltages, such as in automotive cold crank or start-stop scenarios when the battery voltage can drop as low as 3V. Alternatively, the boost controller can be driven from one of the step-down outputs, providing four precisely regulated outputs with a very compact solution footprint.

The LT8603’s triple buck synchronous rectification topology delivers up to 93% efficiency while Burst Mode operation keeps quiescent current under 28µA (high voltage channels active) in no-load standby conditions, suitable for always-on systems. For noise-sensitive applications, the LT8603’s low EMI design meets the CISPR 25, Class 5 EMI requirements even when switching at 2MHz. The LT8603’s switching frequency can be programmed from 250kHz to 2.2MHz and is synchronisable throughout this range.

The LT8603’s 85ns (max) minimum on-time and cascading topology enables 16VIN to 0.8VOUT step-down conversions while switching at 2MHz, enabling designers to avoid critical noise-sensitive frequency bands such as AM radio, while using a very compact solution footprint. Its 3-42V input voltage range is suitable for automotive applications that must regulate through cold crank and stop-start scenarios with minimum input voltages as low as 3V and load dump transients in excess of 40V.

Programmable power-on reset and power good indicators for each channel ensure overall system reliability. The LT8603’s 40-lead thermally enhanced 6x6mm QFN package and high switching frequency keep external inductors and capacitors small, providing a compact, thermally efficient footprint.

The LT8603 is available in a thermally enhanced 40-lead 6x6mm QFN package. Two temperature grades are available, with operation from –40 to 125°C (junction) for the extended E- and industrial I-grades.