Synchronous step-down silent switcher limits EMI/EMC emissions

Linear Technology has announced the LT8614, a 4A, 42V input capable synchronous step-down switching regulator.Its Silent Switcher architecture reduces EMI/EMC emissions by more than 20dB, well below the CISPR 25 Class 5 limit.

Even with switching frequencies in excess of 2MHz, synchronous rectification delivers efficiency as high as 96% while Burst Mode operation keeps quiescent current under 2.5µA in no-load standby conditions. Its 3.4V to 42V input voltage range makes it ideal for automotive and industrial applications.

The LT8614’s internal high efficiency switches can deliver up to 4A of continuous output current to voltages as low as 0.97V and its Burst Mode operation provides ultralow quiescent current, making it suited for applications such as automotive “always-on” systems, which need to extend operating battery life. The LT8614’s unique design maintains a minimum dropout voltage of only 200mV at 1A under all conditions, enabling it to excel in scenarios such as automotive cold-crank. Furthermore, a fast minimum on-time of only 30ns enables 2MHz constant frequency switching from a 16V input to a 1.0V output, enabling designers to optimize efficiency while avoiding critical noise-sensitive frequency bands. The LT8614’s 20-lead 3mm x 4mm QFN package and high switching frequency keeps external inductors and capacitors small, providing a compact, thermally efficient footprint.

The LT8614 uses 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 10mVPK-PK. Special design techniques and a new high speed process enable high efficiency over a wide input voltage range, and the LT8614’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 LT8614EUDC is packaged in a 3mm x 4mm QFN package and an industrial temperature version, the LT8614IUDC, is tested and guaranteed to operate from a -40°C to 125°C operating junction temperature. An automotive temperature version, the LT8614HUDC, is tested and guaranteed to operate from a -40°C to 150°C operating junction temperature.


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