Step-down DC/DC rates for 1.5A/2MHz & 3.0-42V inputs

April 21, 2016 // By Graham Prophet
LT8608 is a 1.5A, 42V input synchronous step-down switching regulator. Its synchronous rectification topology delivers 93% efficiency while switching at 2 MHz 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 2.5 µA in no-load standby conditions for always-on systems. Its 3.0V to 42V input voltage range suits it to automotive applications which must regulate through cold-crank and stop-start scenarios with minimum input voltages as low as 3.0V 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 200 mV (500 mA) under all conditions. Spread spectrum frequency modulation and special design techniques offer low EMI operation to minimize noise concerns in automotive and industrial environments. Fast minimum on-time of 45 nsec enables 2 MHz 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 employs 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[P-P]. Its design techniques and a 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 is tested and guaranteed to operate from a -40°C to 125°C operating junction temperature. Pricing starts at $2.25 (1,000)


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