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Step-Down DC/DC Converter Draws Only 75uA and Withstands 62V Transients

2nd April 2009

ES Admin

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Linear Technology has announced the LT3972, a 3.5A, 33VIN step-down switching regulator with Burst Mode operation to keep quiescent current under 75uA. The LT3972 operates within a VIN range of 3.6V to 33V, with overvoltage lockout protection against transients as high as 62V, making it ideal for load dump and cold-crank conditions commonly found in automotive applications.

Its internal 4.6A switch can deliver up to 3.5A of continuous output current at voltages as low as 0.79V. Its Burst Mode operation provides ultra-low quiescent current, well suited for applications such as automotive or telecom systems, which have always-on circuits and need to optimize battery life. Switching frequency is user programmable from 200kHz to 2.4MHz, enabling the designer to maximize efficiency while avoiding critical noise-sensitive frequency bands. Its 3mm x 3mm DFN-10 package (or thermally enhanced MSOP-10E) and high switching frequency keep external inductors and capacitors small, providing a compact, thermally efficient footprint.

The LT3972 utilizes a high efficiency 4.6A, 95mOhm switch, with the necessary boost diode, oscillator, control and logic circuitry integrated into a single chip. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping output ripple below 15mVPK-PK. Special design techniques used in the LT3972 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 external synchronization (from 250kHz to 2MHz), a power good flag and soft-start capability.