Synchronous step-down DC-DC converter offers 93% efficiency

A new 1.5A, 42V input synchronous step-down switching regulator the LT8608 has been introduced by Linear Technology. The device's novel synchronous rectification topology delivers 93% efficiency while switching at 2MHz enabling designers to avoid critical noise-sensitive frequency bands, such as AM radio, while using a very compact solution footprint. Burst Mode operation keeps quiescent current under 2.5µA in no-load standby conditions making it ideal for always-on systems. The device's 3V to 42V input voltage range makes it ideal for automotive applications which 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. Its internal 2A switches can deliver up to 1.5A of continuous output current. The LT8608 maintains a minimum dropout voltage of only 200mV (@500mA) under all conditions, enabling it to excel in scenarios such as automotive cold-crank. Spread spectrum frequency modulation and special design techniques offer low EMI operation to minimize noise concerns in automotive and industrial environments. Furthermore, a fast minimum on-time of only 45ns enables 2MHz constant frequency switching from a 16V input to a 1.5V output. The LT8608’s 10-lead thermally enhanced MSOP package and high switching frequency keeps external inductors and capacitors small, providing a compact, thermally efficient footprint. The LT8608 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 10mVP-P. Unique design techniques and a new high speed process enable high efficiency over a wide input voltage range, and the LT8608’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 LT8608EMSE is packaged in thermally enhanced MSOP-10 package. An industrial temperature version, the LT8608IMSE operates from -40C to 125C operating junction temperature.