Electronic Design

15-V, 4-MHz Synchronous Step-Down Regulator Delivers 5-A Output

Using a frequency-controlled, current-mode architecture, the LTC3605 4-MHz synchronous buck regulator from Linear Technology delivers up to 5 A of continuous output current at output voltages as low as 0.6 V. The regulator operates from a 4- by 4-mm quad flat no-lead (QFN) package with minimum thermal derating. Input voltage ranges from 4 to 15 V, making it well suited for dual-cell lithium-ion (Li-ion) applications, as well as fixed rail systems with voltages up to 12 V. A user-programmable, 800-kHz to 4-MHz switching frequency allows for the use of tiny, low-cost capacitors and inductors.

The LTC3605 uses internal N-channel MOSFET switches with RDS(ON) values of only 35 and 70 mΩ to deliver efficiencies as high as 96%. Its low minimum on-time supports low-duty-cycle operation at high switching frequencies. Using PolyPhase operation (up to 12 phases), multiple regulators can be cascaded, running out-of-phase to minimize input and output capacitance. Current-mode operation offers fast transient response while simplifying compensation. Additional features include output tracking and a shutdown current of only 15 µA.

The LTC3605EUF is available from stock in a 4- by 4-mm QFN-24 package. Pricing starts at $4.25 each in 1000-piece quantities.

Linear Technology


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