DC-DC Converter - Isolated Power Source Uses

Summary

This video explores the functionality and applications of isolated DC-to-DC converters. It explains how these converters transform DC voltage through an inverter and transformer to provide isolated DC output, which is crucial for safety in medical applications and for eliminating ground loops. The script also discusses the importance of isolation in protecting against ESD, miswiring, and noise propagation. Practical examples include using the converters for creating split rail supplies and boosting voltage levels, showcasing the versatility of these devices in various electronic setups.

Takeaways

• 🔌 Isolated DC-to-DC converters are used to convert DC voltage into an isolated DC output, which can be useful for safety and noise reduction in circuits.
• 🔄 The process involves an inverter converting DC to AC, which is then transformed and rectified back to DC, creating an isolated output.
• 🏥 These converters are particularly useful in applications requiring safety isolation, such as medical devices, to prevent accidental current flow.
• ⚡ They help in minimizing or eliminating ground loops, which can cause noise and interference in electronic systems.
• 💻 Isolation can protect against ESD hits and miswiring, which could otherwise cause damage or system reboots.
• 🔗 The script discusses the use of isolation in USB measurements and DMX lighting applications to protect expensive equipment from harmful surges.
• 📈 The O 5 o 5 converter mentioned in the script converts 5V DC to an isolated 5V DC output, with a current capability up to 200mA.
• 🔍 The efficiency of the converter can range from 76% to 80%, and it requires a minimum load of 20mA to function correctly.
• 🔬 Experiments shown in the script demonstrate how to create various voltage rails (like 10V or 13V) by combining the isolated output with other voltage sources.
• 🛠️ The script provides practical examples of using isolated DC-to-DC converters for creating split rail supplies and for experimenting with voltage combinations.
• 📚 Understanding the datasheet and choosing the right converter based on regulation, efficiency, and output voltage stability is crucial for successful circuit design.

Q & A

What is an isolated DC-to-DC converter and how does it work?

An isolated DC-to-DC converter is a device that takes a DC input voltage, converts it to an AC voltage through an inverter, and then uses a transformer to generate an AC voltage in the secondary winding. This AC voltage is subsequently rectified back into DC, resulting in an isolated DC output. This process allows for the interaction of two separate circuits where grounds may not be at the same potential, preventing direct connection.

Why would you use an isolated DC-to-DC converter?

Isolated DC-to-DC converters are used to provide safety isolation, eliminate ground loops, and protect against ESD hits. They are also used in applications where maintaining separate ground potentials is necessary, such as in medical equipment or systems where different parts may have different ground potentials.

How can isolation help in minimizing or eliminating ground loops?

Isolation can help minimize or eliminate ground loops by preventing the connection of grounds between different sections of a system. This separation prevents the circulation of current between grounds, which can cause noise and interference.

What are some applications where isolated DC-to-DC converters are particularly useful?

Isolated DC-to-DC converters are particularly useful in applications such as medical equipment for safety reasons, in systems prone to ESD hits, and in environments where noise from long cables or inductive loads could interfere with sensitive circuits.

What is the significance of the isolation barrier in the context of the script?

The isolation barrier, represented by a dashed line, separates two sides of a circuit. It ensures that the noise and voltage spikes from one side do not affect the other, keeping the receiver side clean and stable.

How does the O 5 o 5 isolated DC-to-DC converter mentioned in the script work?

The O 5 o 5 converter takes a 5 volts DC input and provides an isolated 5 volts DC output. It can supply up to 200 milliamps and requires a minimum load of 20 milliamps to operate correctly. The efficiency is between 76% to 80%, and the output voltage may fluctuate due to its unregulated nature.

What is the purpose of the load resistor mentioned in the script?

The load resistor is used to ensure that the converter is always drawing at least 20 milliamps, which is the minimum load current required for the converter to function properly.

Can you explain the experiment with the floating 5 volts and the 18 volts supply as described in the script?

In the experiment, the floating 5 volts can be connected in series with the 18 volts supply to create a 23 volts supply by connecting the positive of the floating 5 volts to the positive of the 18 volts. Conversely, by reversing the polarity of the floating 5 volts, it can be used to subtract 5 volts from the 18 volts, resulting in a 13 volts supply.

What is the significance of the floating ground in the isolated DC-to-DC converter?

The floating ground allows for flexibility in how the converter's output can be used. It can be treated as a separate reference point, enabling the creation of split rail supplies or the combination of voltages in series or parallel without being tied to a common ground.

How can the isolated DC-to-DC converter be used to create a split rail supply as mentioned in the script?

By connecting the negative output of the isolated converter to the positive input of the same converter, a split rail supply can be created. This setup allows for both positive and negative voltages relative to a common ground, which can be useful for certain circuit applications like op-amps.