Power Electronics
42-V, 4-A Synchronous Step-Down Silent Switcher

42-V, 4-A Synchronous Step-Down Silent Switcher

The LT8614 from Linear Technology Corp. is a 4-A, 42-V input capable synchronous step-down switching regulator. A unique Silent Switcher™ architecture reduces EMI/EMC emissions by more than 20 dB, well below the CISPR 25 Class 5 limit. Even with switching frequencies in excess of 2 MHz, synchronous rectification delivers efficiency as high as 96% while Burst Mode® operation keeps quiescent current under 2.5 µA in no-load standby conditions. Its 3.4 V to 42 V input voltage range makes it ideal for automotive and industrial applications.

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

The LT8614 utilizes 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 10 mV PK-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 is priced starting at $4.25 each. An industrial temperature version, the LT8614IUDC, is tested and guaranteed to operate from a -40 °C to 125 °C operating junction temperature and is priced starting at $4.68 each. An automotive temperature version, the LT8614HUDC, is tested and guaranteed to operate from a -40 °C to 150 °C operating junction temperature and is priced starting at $4.93 each. All pricing is for 1,000-piece quantities and all versions are available from stock.

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