Almost all electronic circuits today require multiple power supply voltages. Therefore, a power management architecture must be designed to accommodate the different voltage rails required.


Typically, a multichannel converter using a switching regulator design is used for this purpose. This design method requires each switching regulator to have its own inductor.

For final products, it's crucial to minimize PCB space and lower associated costs. Integration is a common method for achieving these goals.

Circuit integration on semiconductors is particularly suitable for low-power switching regulators and linear regulators. A variety of switching regulator ICs with a high level of integration are available on the market.

These products are also called power management integrated circuits (PMICs). Figure 1 shows the ADP5014, a DC-DC converter product that exhibits such a high level of integration.
To further reduce the size of the circuit in Figure 1, the inductors can be integrated into the package. The LTM4668 in Figure 2 offers just such a solution. The LTM4668 offers four channels and incorporates fairly large inductors within the package, reducing the number of external components required.

The LTM module family offers high power density, excellent EMC performance, and superior ruggedness. However, it can be more expensive than solutions using external components.

A third solution is conceptually similar to Figure 1, but uses a single-inductor multiple output (SIMO) converter.

This solution uses a single inductor as an energy storage device, specifically a current storage device, and all channels share this inductor. This solution can be implemented in various forms.

Some products can charge the inductor at one point and partially discharge this energy into different channels.

Additionally, some products charge and fully discharge the inductor in one channel, then pass this empty energy storage device to the next channel, where it is charged and discharged again, and then passed on to the next channel, supplying energy to all channels.

Power supplies can vary in their characteristics depending on the implementation. Generally, this concept is well suited to relatively low power applications, due to the small size of the internal MOSFETs and the use of a single external inductor.

The MAX77655's internally integrated switches not only enable all channels to be powered using a single inductor, but also allow for the conversion of available voltages to higher or lower levels. Appropriately driving the internal MOSFETs enables specific operating modes.

The SIMO converter in Figure 3 can efficiently generate multiple voltages using only one energy storage inductor. This allows for a more compact power management architecture and lower costs.

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※ About the author
By Frederik Dostal, Senior Engineer, Analog Devices, Inc.

Frederik Dostal is a power management expert with over 20 years of experience. He studied microelectronics at the University of Erlangen, Germany. He joined National Semiconductor in 2001, where he gained extensive experience implementing power management solutions on customer projects as a Field Application Engineer (FAE). He then worked in Phoenix, Arizona, for four years, focusing on switch-mode power supplies as an applications engineer. He joined Analog Devices in 2009 and has since held various positions across product lines and supporting European customers. Currently, he is based in Munich, Germany, as a power management expert, bringing his extensive design and application knowledge to the ADI office. Contact: frederik.dostal@analog.com