High-Efficiency Dual Regulator Outputs 300 mA Per Channel

The LTC3547 is a dual-channel, high-efficiency synchronous buck regulator that delivers up to 300 mA of continuous output current per channel from a 3- by 2-mm DFN package. Using a constant-frequency current-mode architecture, the device operates from an input of 2.5 to 5.5 V, making it well suited for single-cell Li-Ion/polymer or multi-cell alkaline/NiCad/NiMH applications. The regulator generates outputs as low as 0.6 V, allowing it to power the latest generation of low-voltage DSPs and microcontrollers. Because of its 2.25-MHz switching frequency, the LTC3547 can use very small, low-cost ceramic capacitors and inductors less than 1 mm high.

The regulator's internal switches feature an R_DS(ON) of only 0.75 Ω (N-Channel) and 0.80 Ω (P-Channel), enabling efficiencies as high as 96%. It also implements a low-dropout 100% duty-cycle operation to allow output voltages up to V_IN, further extending battery run-time. The device incorporates low-ripple Burst Mode operation, so the no-load quiescent current (both channels) is only 40 µA with an output ripple of only 20 mV pk-pk. Shutdown current is less than 1 µA. Other features include independent internal soft-start for each channel and short-circuit and over-temperature protection.