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Automotive & Transportation

1.5 A Step-Down DC/DC Converter Is 93% Efficient, Accepts 42 V Input

20 April 2016

Linear Technology Corporation has announced the LT8608, a 1.5 A, 42 V input synchronous step-down switching regulator. A 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, making it ideal for always-on systems.

Linear Technology’s LT8608 step-down switching regulator. Source: Linear TechnologyLinear Technology’s LT8608 step-down switching regulator. Source: Linear Technology

The regulator’s 3.0 V to 42 V 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 3.0 V and load dump transients in excess of 40 V. Its internal 2 A switches can deliver up to 1.5 A of continuous output current.

The LT8608 maintains a minimum dropout voltage of only 200 mV (500 mA) under all conditions, making it ideal for applications 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 45 ns enables 2 MHz constant frequency switching from a 16V input to a 1.5 V 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 10 mVP-P. 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 comes in a 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 each in 1,000-piece quantities and both versions are available from stock.

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