Power conversion: analog or digital, or both?

We live in an analog world after all. This puts digital solutions at a disadvantage because it requires the information (feedback) to be digitized (usually done via an analog-to-digital converter ), and then the digital control must be processed in a high-speed MCU (or DSP). The bandwidth of the digital control loop is directly related to the speed of the A/D conversion and the calculation speed of the MCU/DSP. Want more bandwidth? Then you need a faster A/D and MCU, which of course costs more! The inherent advantage of analog solutions is that they collect and maintain information in the analog domain, so there is no need for a high-performance MCU or A/D converter.

While analog power solutions offer efficient control, they are not very flexible. Analog power design engineers must evaluate the performance trade-offs in their applications and then optimize the analog design for the entire operating space and load profile. While this technology was adequate for many years, market and industry trends, consumer expectations, and government regulations will soon outstrip the capabilities of analog design technology to meet the need for greater efficiency. Solution: Power devices must have greater flexibility. In addition to general purposes, this flexibility can be used to:

1. Optimize power conversion at multiple points rather than over the entire power conversion operating range

2. Perform as part of a system, which means it must be configurable to optimize the efficiency of the system over time, rather than just optimizing power conversion efficiency

3. Pass information to the system to enable system optimization

There is no doubt that digital power conversion solutions are flexible enough to meet the above needs. However, their design is not easy and requires a significant investment in resources, tools and processes. Digital control technology is different from analog control technology, so new resources are required, including digital control design and software engineering. For many companies, this investment has proved to be a serious obstacle.

Considering these opportunities and challenges, it makes sense to explore the possibility of keeping power control in the analog domain. In addition, this eliminates the need for additional specialized skills and resources, while avoiding increased product costs by eliminating the expensive MCU and A/D converters required for digital control.

Let's look at a hybrid analog and digital solution, such as Microchip's newly released MCP19111. The MCP19111 combines the performance of a peak current mode analog controller with a small 8-bit microcontroller (see Figure 1 - Block Diagram). Its power regulation is completely performed in the analog domain, so a high-performance, high-speed microcontroller is not required. The integrated 8-bit MCU provides a convenient interface to monitor and adjust the performance of the analog controller, thereby enabling previously unavailable regulation functions. The integrated MCU remains small and simple, and in addition to increasing flexibility, it also achieves a high level of integration. As shown in Figure 1, the MCP19111 not only integrates an MCU with an analog controller, but also includes power MOSFET drivers and a medium-voltage LDO. This device has a very wide operating range of up to 4.5-32V, requires very few external components, and introduces unprecedented flexibility in analog control.

The power conversion industry continues to transition to more flexible and customizable digital power conversion technology, while analog power conversion technology will continue to provide cost-effective, high-performance power conversion solutions. The combination of the two, whether called hybrid power conversion, mixed-signal power conversion or simply analog plus digital power conversion, introduces a unique balance of performance, flexibility and cost that is very attractive in many different types of applications.

Figure 1. MCP19111 block diagram