Why use isolated gate drivers?
The needs and applications of information exchange and retrieval are ubiquitous. For example, not a single minute can be wasted while using a smart device. Check out what’s on social media, messages or emails. All of this happens in the cloud. This cloud is the workhorse of global real-time connectivity. The cloud actually resides within the data center. Information to and from the data center is transmitted over lines such as fiber optic or coaxial cables, or wirelessly through telecommunications base stations. Data centers contain power delivery units, commonly referred to as "power supplies." Information is stored in servers called "cloud servers". These servers require robust capabilities to store information and make it available for retrieval by clients. These power supply units range in power from a few hundred watts to several kilowatts. They use the grid (AC line voltage in the hundreds of volt range). Hence, they are called high voltage units.
To improve server efficiency, several low-voltage components are required, such as controllers and communication components. Also, these servers are sold with efficiency ratings, so these ratings must be followed. Also, during the cloud operation, humans interact with the server through the HMI. Current breakdown and leakage of current from the high-voltage unit into the HMI must be avoided, as such problems can damage all low-voltage components, such as controllers and communication components.
The solution is to isolate
As a semiconductor integrated circuit (IC), the isolation device allows data and power to be transferred between high-voltage and low-voltage units while preventing any dangerous direct current or uncontrolled transients from flowing out of the grid. A well-known example is lightning strikes. Ground loops formed in circuits with high energy flow can be broken through isolation. There are several methods of isolation. Among all isolation methods, galvanic isolation is one that provides protection against large potential differences.
This demand for electricity continues to increase every day. Not only that, people want this information immediately. This means that as data demand increases, so does the capacity of data centers; therefore, power delivery systems are required to provide more and more power. However, data centers have limited computer room space. Expanding the computer room space is expensive and uneconomical.
One way to address this need is to increase power density and ensure isolation reliability. To achieve this, power supply efficiency and power transfer rate (also known as switching frequency, measured in kHz) can be significantly increased. This improvement helps reduce the size of the power supply unit. Robust isolation can be achieved by integrating the isolator with critical power components, namely high-speed gate drivers. This integrated device is known as an isolated gate driver.
Gate driver function
To further understand the value of this integrated solution, it is first necessary to understand how gate drivers are used. Gate drivers are implemented in systems using switch-mode power supplies, where the power switches operate in ON and OFF modes, so ideally they operate at high switching frequencies with zero power consumption. Two commonly used power switches are power MOSFETs and IGBTs. Switch-mode power supplies operate in a controller-based closed-loop power supply topology. The ON/OFF state is controlled on the gates of these switches to regulate the voltage and current through the switch. Let’s take a power MOSFET as an example. The operation of the gate terminal is explained.