【ShiShuo Design】4 tips for miniaturizing power supply design

Latest update time：2022-07-27 20:27

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Miniaturization has always been a hot topic in the electronics industry, and it is especially important for power supplies. The quality of a power supply is usually measured by power per unit volume. This article discusses some considerations that help achieve miniaturized power supply design.

Minimize external component count

A power supply is usually composed of at least one semiconductor and several passive external components such as an inductor, capacitor, and a few resistors. Reducing the number of components to that shown in Figure 1 is the first step in shrinking the size of the entire power supply.

Figure 1. Classic switching regulator.

Contains a semiconductor and several passive components.

If additional features are required, such as adjustable output voltage or adjustable soft-start time, the number of passive components increases, increasing the space required for the entire solution. The circuit in Figure 1 is an example of a switching buck converter where the number of passive components required has been minimized.

Minimize the size of external components

To achieve the smallest possible output capacitor and inductor size, the switching regulator IC must have the highest possible switching frequency. The voltage ripple of the output voltage is basically linear with the value and size of the external components. For example, if the switching frequency is doubled, the inductor value required to achieve the same output voltage ripple will be halved. This allows the design size to be reduced. Figure 2 shows the space requirements of the LTC3307A switching regulator. Due to the high switching frequency of 3MHz, a small inductor can be used.

Figure 2. Space requirements for a switch-mode voltage converter with 3 A output current.

Minimizing the size of switching regulator ICs

ADI's LTC33xx platform consists of switching buck converters with switching frequencies up to 5 MHz, and special products are designed for various applications through the LTC33xx platform. The LTC3315A has been optimized for space-limited applications. It is a dual-channel converter that can provide 2 A of output current per channel in a wafer-level chip scale package (WLCSP) measuring only 1.64 mm × 1.64 mm. Also worth mentioning is the MAX77324, which is a single-channel buck switching regulator with a maximum output current of 1.5 A and a case size of 1.22 mm × 0.85 mm. Figure 3 shows the MAX77324 package size.

Figure 3. A switching regulator in an extremely small package.

Figure 4. Dual buck regulator IC package outline.

The dimensions are 1.64 mm × 1.64 mm.

Reduce size by integrating inductors

Another way to reduce the size of power supply circuits is to combine an inductor with a switching regulator IC. This combination is called a module. By integrating, the inductor is placed on the semiconductor IC, making it possible to reduce the edge length. Another obstacle to miniaturization can be overcome by using the inductor in the module as a thermal conductor and heat sink. Properly connecting the inductor to the chip within the power module allows the semiconductor to dissipate heat better. Especially for small switching regulator ICs with high output currents, heat dissipation is becoming an increasingly large problem because the chip cannot be used at a temperature exceeding the maximum allowable operating temperature.

There are many ways to reduce the size of power supplies using innovative techniques. This short article on power management techniques introduces some of these methods. Miniaturization brings additional indirect advantages, such as the possibility of creating more functional technical devices due to reduced board space requirements and reduced costs, which brings greater benefits, and even reduces shipping costs due to smaller and lighter electronic devices.

Original article from Analog Devices

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