The LTM4691 is a high efficiency, dual output step-down µModule® buck regulator capable of 2 A continuous output current for each channel from input voltages between 2.25 V and 3.6 V. This switch-mode power supply comes in a tiny 3 mm × 4 mm × 1.18 mm LGA package. This small footprint comprises the switching controller, power FETs, inductors, and all supporting components. Each output is independently resistor programmable from 0.5 V to 2.5 V.
The LTM4691 can deliver 2 A per output with just a few small capacitors and resistors. The µModule regulator includes internal feedback loop compensation, reducing the number and size of additional components. The switching frequency defaults to 2 MHz without any external component or input, but it can be synchronized to a 1 MHz to 3 MHz external clock. To maximize the performance of the feedback loop, only a few small external capacitors need be added to complete the internally compensated loop—yielding sufficient stability margins and good transient performance. Other features include a PGOOD signal, output overvoltage protection, overtemperature protection, precision run thresholds, and output short-circuit protection.
Small Solution Using All-Ceramic Capacitors
Figure 3 shows the scheme for a compact, all-ceramic capacitor solution, which takes maximum advantage of the internal circuitry of the LTM4691. Figure 2 shows a photo of the tiny solution. Figure 4, Figure 5, Figure 6, and Figure 7 show the thermal performance, efficiency, and load step performance for a DC2910A demo board.
The LTM4691’s compact footprint and low profile enable it to fit tight spaces. Arguably just as important for compact designs: the LTM4691’s thermal performance and efficiency are high, minimizing the need for bulky thermal mitigation components. Likewise, transient performance and output stability are not sacrificed to fit the tiny package.