Linear Tech Releases 15V, 4MHz, Synchronous Dual 3A Step-Down Regulator in 4 x 5mm QFN Package

Linear Technology released its LTC3633 – a 4MHz synchronous dual output buck regulator that incorporates what is described as a unique constant frequency/controlled on-time, current mode architecture. It can deliver up to 3A of continuous output current from each channel at output voltages as low as 0.6V from a 4m x 5mm QFN package. The LTC3633 operates from an input voltage of 3.6 to 15V, making it well suited for dual-cell Li-Ion applications as well as 5 and 12V intermediate bus systems. Its switching frequency is user programmable from 800kHz to 4MHz, enabling the use of tiny, low cost capacitors and inductors.

Each channel of the LTC3633 uses internal switches with R_DS(ON) of only 50 and 80mΩ to deliver efficiencies as high as 96%. Its unique control architecture enables it to achieve duty cycles as low as 5% while maintaining switching frequencies as high as 2.25MHz, making it ideal for high step-down ratio applications such as 12V_IN to 1.2V_OUT conversions. The two channels run 180 degrees out of phase, minimizing the size of both input and output capacitance. Burst Mode® operation is used to maximize light load efficiency, requiring only 500µA at no load, making it well suited for applications demanding maximum battery run time. For applications that require the lowest possible noise, the LTC3633 can be configured to run in pulse skipping or forced continuous mode, reducing supply ripple and potential RF interference. Additional features include Power Good voltage monitors, output voltage tracking capability, independent soft-start capability for each channel and short circuit protection.

The LTC3633EUFD is available in a 4 x 5mm QFN-28. Pricing starts at $4.25 each in 1,000-piece quantities. The LTC3633EFE is available in a TSSOP-28 thermally enhanced package with pricing start at $4.40 each in 1,000-piece quantities. Industrial grade versions, the LTC3633IUFD and LTC3633IFE, are guaranteed to operate over the -40 to 125°C operating junction temperature range and the LTC3633IUFD is priced at $4.72 each in 1,000-piece quantities and the LTC3633IFE is priced at $4.89 each in 1,000-piece quantities.