Synchronous buck converter delivers 90 percent efficiency

May 31, 2012 // By Paul Buckley
Linear Technology has released a 65 V input-capable synchronous buck converter, which delivers up to 500 mA of continuous output current from a 16-lead thermally enhanced 3 mm x 5 mm DFN or MSOP package.

The device’s internal synchronous rectification topology delivers efficiencies as high as 90% and its Burst Mode operation requires 12 µA of quiescent current (at no load), maximizing battery run time. The LTC3630 operates from an input voltage range of 4 V to 65 V, making it suitable for a wide range of applications, including automotive, industrial, medical and avionics.

The LTC3630’s internal synchronous rectification and its programmable peak current limit design optimize efficiency while minimizing output ripple and external component size. Furthermore, output current can be programmed between 50 mA and 500 mA with a single resistor. The LTC3630’s output voltage can be adjusted with an external resistor divider to voltages from 0.8 V to VIN, or it can be easily programmed to deliver a fixed 1.8 V, 3.3 V or 5 V output with 1% accuracy. The combination of its 3 mm x 5 mm DFN package or thermally enhanced MSOP-16E and only three tiny externals offers a highly compact solution footprint for a wide array of general purpose applications.

The LTC3630 utilizes internal high side and low side power MOSFETs to ensure high efficiency in a very compact footprint. Additionally, the LTC3630 offers a precise run threshold and soft-start feature to ensure that system start-up is well controlled in any environment. Furthermore, a feedback comparator output enables multiple LTC3630s to be paralleled for higher current applications. Due to the inherent stability of the converter, no external compensation is required, thereby minimizing the solution footprint.

Availability and Pricing

Pricing for the LTC3630EDHC and the LTC3630EMSE starts at $3.20 each. Industrial grade versions, the LTC3630IDHC and LTC3630IMSE, are tested and guaranteed to operate over a -40 to 125°C operating junction temperature range and are priced at $3.55 each. Automotive grade versions, the LTC3630HDHC and LTC3630HMSE, are tested and guaranteed to operate from -40 to 150°C operating junction temperature and are priced at $3.80 each. Military Plastic grade versions, the LTC3630MPDHC