15-V, 4-MHz Synchronous Step-Down Regulator Delivers 1.5 A

The LTC3601 is a high-efficiency, 4-MHz synchronous buck regulator that incorporates a controlled-frequency, current-mode architecture. It can deliver up to 1.5 A of continuous output current at output voltages as low as 0.6 V from a 3-mm x 3-mm QFN or a thermally enhanced MSOP-16 package. The LTC3601 operates from an input voltage of 4 V to 15 V, suiting it for dual-cell Li-ion applications as well as 12-V intermediate bus systems. Its switching frequency is user-programmable from 800 kHz to 4 MHz, enabling the use of small, low-cost capacitors and inductors. The LTC3601 uses internal switches with an R_DS(ON) of only 100 mOhm and 130 mOhm to deliver efficiencies as high as 96%. Its control architecture enables it to achieve duty cycles as low as 5% while maintaining switching frequencies as high as 2.25 MHz, making it a good candidate for high step-down-ratio applications, such as 12 V_IN to 1.2 V_OUT conversions. Burst-mode operation is used to maximize light-load efficiency requiring only 300 µA at no load, making it well suited for applications demanding maximum battery run time. For applications that require the lowest possible noise, the LTC3601 can be configured to run in forced continuous mode, reducing noise and potential RF interference. The LTC3601EUD is available in a 3-mm x 3-mm QFN-16, and the LTC3601MSE is offered in a 16-lead, thermally enhanced MSOP package. Pricing for both package options starts at $2.30 each in lots of 1000. Industrial grade versions, the LTC3601IUD and LTC3601IMSE, are guaranteed to operate over the -40ºC to 125ºC operating junction temperature range and are priced at $2.71 each in similar quantities. All versions are available from stock. LINEAR TECHNOLOGY CORP., Milpitas, CA. (408) 432-1900.