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Step-down regulator packs burst mode ops

Posted: 19 Oct 2009     Print Version  Bookmark and Share

Keywords:switching regulator  quiescent current  automotive 

Linear Technology Corp.'s new step-down switching regulator with burst mode operation maintains quiescent current under 85µA. The 2A, 58VIN LT3980 operates within a VIN range of 3.6V to 58V, with over-voltage lockout protection against transients as high as 80V. Its internal 3.4A switch can deliver up to 2A of continuous output current at voltages as low as 0.79V. The LT3980 suits load dump and cold-crank conditions commonly found in automotive applications, and telecom systems that have always-on circuits and demand optimal battery life.

Switching frequency is user programmable from 100kHz to 2.4MHz, enabling the designer to maximise efficiency while avoiding critical noise-sensitive frequency bands. The combination of a 3mm x 4mm DFN-16 package (or thermally enhanced MSOP-16E) and high switching frequency keeps the LT3980's external inductor and capacitors small, providing a compact, thermally efficient footprint.

The LT3980 utilises a high efficiency 3.4A, 200mΩ switch, with the necessary boost diode, oscillator, control and logic circuitry integrated into a single chip. Its catch diode current sense (DA pin) protects the circuit during input voltage transients even at high switching frequencies. 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 LT3980 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 synchronisation (from 250kHz to 2MHz), a power good flag and soft-start capability.

Pricing for the LT3980EDE and LT3980EMSE starts at Rs.173.29 ($3.55) each, for 1,000-piece quantities. The LT3980IDE and LT3980IMSE are guaranteed to operate from a -40°C to 125°C operating junction temperature, priced at Rs.204.05 ($4.18) each, in 1,000-piece quantities. The LT3980HMSE is guaranteed to operate from a -40°C to 150°C operating junction temperature and is priced at Rs.216.25 ($4.43) in 1,000-piece quantities. All versions are available from stock.

Get related application notes and technical articles on Power Design India.

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