Dual Buck Converter Fits in Tiny DFN

Dec 14, 2005 11:49 AM

Linear Technology’s LTC3417, a dual-output, high-efficiency 4-MHz, synchronous buck regulator, delivers up to 1.4 A of continuous output current from one channel and up to 800 mA from the second. Using a constant frequency and current-mode architecture, the LTC3417 operates from an input voltage range of 2.25 V to 5.5 V, making it suitable for single-cell Li-Ion, multicell Alkaline or NiMH applications. It can generate two independent output voltages as low as 0.6 V, enabling it to power the latest generation of low-voltage DSPs and microcontrollers.

Its switching frequency of up to 4 MHz allows the use of low-cost ceramic capacitors and inductors. The combination of dual outputs, current-mode architecture and a 5-mm × 3-mm DFN (or TSSOP-20E) package makes the LTC3417 a compact solution for numerous applications.

The LTC3417 uses internal switches with an R_DS(ON) of only 0.088 Ω and 0.160 Ω to deliver efficiencies as high as 95%. It also uses low dropout 100% duty cycle operation to allow output voltages equal to V_IN.

With Burst Mode operation enabled, no load quiescent current is only 125 µA (both channels) and less than 1 µA in shutdown. If the application is noise sensitive, the user can disable Burst Mode, replacing it with a lower noise pulse-skipping mode.

A phase-mode pin enables the second channel to operate in-phase or 180 degrees out-of-phase with respect to channel 1. Out-of-phase operation produces lower RMS current at V_IN, thus lower RMS de-rating on the input capacitor.

The LTC3417EDHC is available from stock in a DFN-16 package, and the LTC3417EFE is available in a thermally enhanced TSSOP package. The LTC3417EDHC starts at $3.35 each, the LTC3417EFE at $3.55 each, both in 1000-piece quantities.

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