Power Supplies: Analog Control or Digital Control

A power supply has the important role of converting incoming AC voltage into smooth DC voltage for the application. Traditional power supplies are analog, but digital power supplies have introduced more flexibility and capabilities.

Typically, when discussing the distinction between analog and digital power supplies, we're really looking at just one circuit. Power supplies rely on a power conversion circuit, a supervisory control circuit, and a control circuit. The control circuit is the one under scrutiny. The power supply itself is usually still analog-based, and power supplies can even use both analog and digital control systems.

While the features of digital power supplies are useful, they also introduce new challenges. Let's explore the difference between analog control and digital control systems and how you can choose the right one for your application.

What Is an Analog Power Supply?

An analog-controlled power supply uses an analog control circuit. This circuit delivers feedback to the primary control circuit with conventional voltage or current sensing systems, error amplifiers, and optocouplers. It can monitor and control output voltages and the power factor correction (PFC). However, if parameters need to be changed, you must change the hardware or design of the circuit.

What Is a Digitally Controlled Power Supply?

A digitally controlled power supply has a digital circuit that can accomplish the same functions as an analog circuit. It can use sample and hold, digitally perform the comparison, communicate with the primary control circuit, and manage the power conversion circuit. These tasks can be managed by a microcontroller, field-programmable gate arrays (FPGAs), or an application-specific integrated circuit (ASIC). Typically, controls can be located via a screen on the power supply or a software program.

An external host controller can intervene and change the performance in real time by changing target parameters, such as gain and frequency response. Engineers can achieve a wide range of performance variations with simple firmware updates, as opposed to hardware swaps. It offers more flexibility by allowing you to create a generic system and program it according to specific needs. That generic circuit then supports a wide array of power conversion products with simple reprogramming.

Although it might be more complex, it delivers virtually unlimited flexibility for development, manufacturing, and even field service. Supervisory functions can also work with analog or digital circuits.

Analog Control vs. Digital Control for Your Power Supply

The best control method will depend on your application, and the primary difference comes down to flexibility. If you only need your power supply to operate at specific parameters, such as its input, output, wattage, and form factor, you can often save money with an analog-controlled power supply. However, if demands change or the performance isn't quite right, you'd need to either buy another power supply or contact the vendor to make modifications.

Many users need to make regular changes to meet target performance. In these cases, a digitally controlled power supply can meet these flexibility demands without time-consuming adjustments to the hardware. Another option is to use a hybrid system. These systems use analog controls, but the parameters can be set and managed digitally. With the best of both worlds, hybrid power systems are a great way to get flexibility and high performance.

Why Use an Analog-Controlled Power Supply

Analog is a tried-and-true type of design with several benefits:

• Better core power conversion: Analog controls are very stable and offer exceptional performance that's less prone to problems in the current.
• Better availability: Since analog-controlled power supply units are older, they're more common and easy to find. They can also be more affordable.
• Shorter design cycles: The popularity and simplicity of the design mean it's usually much faster to create analog power supplies for different applications. More engineers know how they work.
• Fewer bugs: With such thorough testing and simple designs, analog-controlled power supplies usually have fewer bugs and glitches.

Despite those advantages, analog power supply controls are missing out on some useful capabilities that digital solutions have to offer. Most notably, they're inflexible. Making any changes to the parameters requires adjustments to the hardware or design. It's best suited for applications that don't require this kind of modification. Analog-controlled power supplies also lack advanced monitoring and control capabilities. For example, you can monitor the status, but control is limited to one reaction per parameter.

Generally, the best applications for analog-controlled power supplies are those that use one set of parameters, won't need to be frequently changed and aren't so critical that they need extensive monitoring.

Why Use a Digitally Controlled Power Supply

The benefits of digitally controlled power supplies include:

• Design versatility: Digitally controlled power supplies offer many options. You can control them remotely, set limits on currents and output voltages and add alarms at certain levels.
• Ease of implementation: Digital controls are also much easier to set up and modify. Any changes can be programmed and might require a firmware download, but time-consuming and costly hardware changes aren't necessary.
• Long-term management tools: With a digitally controlled power supply, you can also use more monitoring tools to access detailed information that can help predict failures. For example, ongoing monitoring of fan performance and temperatures could help you identify problems and conduct maintenance before it turns into downtime.
• Faster integration of new systems: As with parameter modifications, digital controls are more suited to adapt to new systems and setups.

Of course, there are some challenges that come with going digital. The increased complexity requires some sophisticated software and can be difficult to troubleshoot.

Hybrid

Another option is to use both analog and digital controls. This combination uses an analog controller with a digital interface, such as I2C, PMBus or CANBUS. The analog controller can offer the strong, steady performance it's known for, while the digital interface delivers improved communication. It takes advantage of analog's high availability, short design cycle, and minimal bugs, and the digital interface delivers control and monitoring solutions.

Find the Right Solution With Astrodyne TDI

Here at Astrodyne TDI, we know that no two applications are the same. That's why we offer a wide range of power supplies and can offer custom solutions for your installation. Our knowledgeable team can help you find or create the right power supply for your needs. We're well-versed in meeting strict requirements for industries like medicine and military.

With decades of experience and ISO 9001 and ISO 13485 certifications, Astrodyne TDI is your trusted source for analog, digital or analog-and-digital power supplies. To learn more, reach out to us today!