Synchronous step-down converter delivers high efficiency

Linear Technology has announced the LT8606, a 350mA, 42V input synchronous step-down switching regulator. A unique synchronous rectification topology delivers 92% 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 3µA in no-load standby conditions, ideal for always-on systems. Its 3V to 42V input voltage range makes it suitable for automotive applications which must regulate through cold-crank and stop-start scenarios with minimum input voltage as low as 3V and load dump transients in excess of 40V. Its internal 650mA switches deliver up to 350mA of continuous output current. The device maintains a minimum dropout voltage of only 175mV (at 300mA) 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, enabling it to meet CISPR25, Class 5 EMI limits required by many automotive and industrial applications. Furthermore, a fast minimum on-time of only 45ns enables 2MHz constant frequency switching from a 16V input to a 1.5V output. The LT8606’s 2mm x 2mm eight-lead DFN or 10-lead thermally enhanced MSOP package and high switching frequency, which keeps the external inductor and capacitors small, provide a compact, thermally efficient footprint. The device 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 high speed process enable high efficiency over a wide input voltage range, and the device’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.