42-V, 2.5-A(IOUT), 2.2-MHz synchronous step-down DC/DC converter delivers 96 percent efficiency

May 21, 2012 // By Paul Buckley
Linear Technology Corporation has introduced a 2.5 A, 42 V input capable synchronous step-down switching regulator. Synchronous rectification delivers efficiency as high as 96% while Burst Mode operation keeps quiescent current under 2.5 µA in no-load standby conditions.

The LT8610’s 3.4 V to 42 V input voltage range makes it ideal for automotive and industrial applications. Its internal 3.5 A switches can deliver up to 2.5 A of continuous output current to voltages as low as 0.97 V. The LT8610’s Burst Mode operation offers ultralow quiescent current, making it well suited for applications such as automotive 'always-on' systems, which need to extend operating battery life.

The LT8610’s design maintains a minimum dropout voltage of only 200 mV (@1A) under all conditions, enabling it to excel in scenarios such as automotive cold-crank. Furthermore, a fast minimum on-time of only 50 ns enables 2 MHz constant frequency switching from a 16 V input to a 1.8 V output, enabling designers to optimize efficiency while avoiding critical noise-sensitive frequency bands. The LT8610’s 16-lead thermally enhanced MSOP package and high switching frequency keeps external inductors and capacitors small, providing a compact, thermally efficient footprint.

The LT8610 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 10mVPK-PK. Special design techniques and a new high speed process enable high efficiency over a wide input voltage range, and the LT8610s’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 LT8611 includes all of the features of the LT8610, plus a built-in current sense amplifier with monitor and control pins, enabling accurate input or output current regulation and limiting. It is offered in a 3 mm x 5 mm 24-lead QFN package.

Availability and Pricing

The LT8610EMSE comes in a thermally enhanced MSOP-16 package and is priced from $3.55 each. An industrial temperature version, the LT8610IMSE, is tested and guaranteed to operate from a -40 to 125°C