DC/DC converter offers very low quiescent current to save battery life

May 21, 2012 // By Christoph Hammerschmidt
At automotive and industrial "always-on" applications is Linear Technology aiming with its LT8610, a 2.5A, 42V input capable synchronous step-down switching regulator. Synchronous rectification delivers efficiency as high as 96% while burst mode operation keeps quiescent current under 2.5µA in no-load standby conditions.

The LT8610's 3.4V to 42V input voltage range makes it ideal for automotive and industrial applications. Its internal 3.5A switches can deliver up to 2.5A of continuous output current to voltages as low as 0.97V. 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 unique design maintains a minimum dropout voltage of only 200mV (@1A) under all conditions, enabling it to excel in scenarios such as automotive cold-crank. Furthermore, a fast minimum on-time of only 50ns enables 2MHz constant frequency switching from a 16V input to a 1.8V 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 3mm x 5mm 24-lead QFN package.

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°C to 125°C operating junction temperature and is priced from $3.91. An automotive temperature version, the LT8610HMSE,