The 2025 Guide to Rectifier Technology and Uses

So, what is a rectifier? A rectifier is an essential electronic component for power conversion, tasked with converting AC to DC.

This fundamental AC to DC conversion process, known as rectification, is the backbone of nearly every modern power supply and piece of electronics. The global rectifier market is projected to grow by 10.61% annually from 2025, a testament to its importance in all electronics. This power conversion process of rectification relies on specialized rectifier diodes. The main types of rectifiers, all using these rectifier diodes, include:

• Half-wave rectifier
• Full-wave rectifier (including the common bridge rectifier)
• Controlled Rectifier (using different rectifier diodes for advanced conversion and rectification)

Key Takeaways

• A rectifier changes AC electricity into DC electricity. This process is called rectification. It powers almost all electronic devices.
• Diodes are like one-way gates for electricity. They are the main parts inside every rectifier. They let current flow in only one direction.
• Rectifiers have different types. Half-wave rectifiers are simple but less efficient. Full-wave rectifiers, like bridge rectifiers, are more efficient and common.
• Filters smooth out the electricity from a rectifier. They remove ripples to make the DC power steady. This protects sensitive electronics.
• Choosing the right rectifier depends on its use. Engineers look at voltage, current, and speed needs. This ensures the power supply works well.
• Modern rectifiers use special diodes like Schottky diodes. These diodes switch very fast. They make devices more efficient, like phone chargers.
• Rectifiers are in many everyday items. They are in TVs, cars, and phone chargers. They also power big industrial machines and telecom networks.

Rectifier Fundamentals

To understand modern electronics, one must first grasp the basics of power conversion. This section explores the fundamental principles of rectification, the components involved, and the metrics used to measure their performance.

What is a Rectifier?

So, what is a rectifier? A rectifier is an electrical device that performs the conversion from alternating current (AC) to direct current (DC). This AC to DC conversion is a one-way process. It allows electrical current to flow in a single direction. The history of this technology dates back to 1874, when German physicist Ferdinand Braun discovered the point-contact rectification effect. He observed that current flowed in only one direction through a galena crystal, laying the groundwork for solid-state electronics. Today, this power conversion process is essential for almost every electronic device, from simple chargers to complex industrial systems. Answering "what is a rectifier" is the first step to understanding how these devices work.

The Role of Diodes in Rectification

At the heart of every rectifier circuit are components called rectifier diodes. A diode acts like a one-way street for electricity. The key characteristics of rectifier diodes enable this unique behavior. This function comes from the diode's internal structure, known as a P-N junction. The key characteristics of rectifier diodes are defined by how this junction behaves.

• Forward Bias: When voltage is applied in the correct direction, the diode permits current to pass through easily. It has very low resistance.
• Reverse Bias: When voltage is applied in the opposite direction, the diode blocks current flow. It acts like an insulator with very high resistance.

This non-symmetrical behavior is central to the process of rectification. The ability of rectifier diodes to switch between low and high resistance allows the rectifier to "steer" the AC input, resulting in a DC output. These key characteristics of rectifier diodes make the entire conversion possible.

Key Performance Metrics

Not all rectifier designs are equal. Engineers evaluate a rectifier based on several key performance characteristics to determine its suitability for a specific application. These metrics define the quality and efficiency of the rectification process.

Rectification Efficiency

Electrical efficiency measures how well a rectifier completes the power conversion from AC to DC. It is the ratio of the DC power delivered to the load versus the AC power supplied at the input. A higher efficiency means less power is wasted as heat during the conversion.

Ripple Factor

The output from a basic rectifier is not perfectly smooth DC. It contains small, leftover AC variations known as "ripple." The ripple factor is a number that quantifies these undesirable voltage fluctuations. A lower ripple factor indicates a smoother, higher-quality DC output. The formula is often expressed as:

The ripple factor (RF) is the ratio of the AC component's effective value (Vac) to the DC component's average value (Vdc). It can be calculated as: RF = Vac / Vdc = sqrt((Vrms / Vdc)² - 1)

Peak Inverse Voltage (PIV)

Peak Inverse Voltage (PIV) is one of the most critical characteristics of rectifier diodes. It represents the maximum voltage a diode can withstand in the reverse-bias direction without failing. If the voltage in the rectifier circuit exceeds the PIV rating of its rectifier diodes, the diode may be permanently damaged. Selecting rectifier diodes with an appropriate PIV rating is crucial for reliable rectification.

Types of Rectifiers

Engineers choose from several types of rectifiers to meet specific application needs. Each design offers a unique balance of simplicity, efficiency, and performance. Understanding these types of rectifiers is key to selecting the right component for any power conversion task. This section explores the most common rectifier configurations.

Half-Wave Rectifiers

The half-wave rectifier is the simplest form of rectifier. Its design uses only a single diode to perform the rectification. This simplicity makes it a good starting point for understanding the conversion process.

A basic half-wave rectifier rectifier circuit connects an AC source to a single diode and a load resistor. The rectifier circuit diagram shows the AC source's positive terminal connecting to the diode's positive side. The diode's negative side then connects to the load. The circuit loop is completed by connecting the load back to the AC source.

During the positive half of the AC cycle, the diode is forward-biased and allows current to pass to the load. During the negative half, the diode is reverse-biased and blocks current flow. This action effectively chops off the negative portion of the AC wave, allowing only the positive pulses to pass.

Efficiency Note: The half-wave rectifier is not very efficient. Its theoretical maximum efficiency is only 40.6%. A large portion of the input power is lost because it does not use the negative half of the AC signal.

Advantages:

• Simple and inexpensive to build.
• Requires only one diode.

Disadvantages:

• Very low efficiency.
• Produces a high ripple factor, resulting in a pulsating DC output.
• Delivers low output power.

Despite its drawbacks, the half-wave rectifier is still useful in certain low-power applications. These include:

• Soldering iron circuits
• AM radio detectors
• Pulse generating circuits
• Voltage multiplier circuits

Full-Wave Rectifiers

The full-wave rectifier improves upon the half-wave rectifier design. It utilizes both the positive and negative halves of the AC input signal. This approach doubles the output frequency and significantly increases efficiency. A full-wave rectifier provides a much smoother and steadier DC output. This makes the full-wave rectifier the standard for most modern electronic devices. The rectification process is more complete, requiring a smaller filter to smooth the final output. There are two main types of rectifiers in this family.

Center-Tapped Configuration

A center-tapped full-wave rectifier uses a special transformer with a connection at the midpoint of its secondary winding. This rectifier circuit also requires two rectifier diodes.

During the positive AC half-cycle, one diode conducts. During the negative half-cycle, the center tap allows the other diode to conduct. This design ensures that current always flows to the load in the same direction. The result is a continuous series of positive pulses.

Advantages:

• Higher efficiency than a half-wave rectifier.
• Smoother output with less ripple.

Disadvantages:

• Requires a bulky and expensive center-tapped transformer.
• The Peak Inverse Voltage (PIV) for each of the rectifier diodes is double the peak output voltage.

Bridge Rectifier Configuration

The bridge rectifier is the most common full-wave rectifier configuration. It uses four rectifier diodes arranged in a "bridge" or diamond pattern. This clever rectifier circuit design eliminates the need for a center-tapped transformer.

The bridge rectifier rectifier circuit works by steering the current through different pairs of rectifier diodes on each half-cycle.

1. During the positive half-cycle, two of the rectifier diodes are forward-biased and conduct current to the load.
2. During the negative half-cycle, the other two rectifier diodes become forward-biased, also directing current to the load in the same direction.

This rectification method is highly efficient and produces a high-quality DC output. The bridge rectifier is a cornerstone of modern power supplies. The bridge rectifier offers the best performance for general-purpose rectification.

Advantages:

• High rectification efficiency (theoretically 81.2%).
• Does not require a special center-tapped transformer.
• Produces a smoother output than a half-wave rectifier.
• The PIV rating for the rectifier diodes is equal to the peak output voltage.

Disadvantages:

• Requires four rectifier diodes instead of one or two.
• The voltage drop across two rectifier diodes slightly reduces the output voltage.

Controlled Rectifiers (SCR-Based)

Controlled rectifiers provide an advanced level of power conversion. Instead of standard rectifier diodes, these circuits use Silicon-Controlled Rectifiers (SCRs). An SCR is a type of diode with a third terminal called a "gate." The gate allows an external signal to control precisely when the SCR turns on.

This control mechanism enables variable voltage output. By delaying the "turn-on" signal sent to the SCR's gate, an operator can adjust the phase angle. A larger delay reduces the time the SCR conducts, which lowers the average voltage delivered to the load. This feature is essential for applications requiring adjustable power. A bridge rectifier circuit can be modified by replacing two of the rectifier diodes with SCRs to create a controlled rectifier.

💡 Did You Know? Fully controlled bridge rectifier circuits using SCRs offer superior efficiency and reduced ripple compared to standard diode bridges. This makes them ideal for high-performance applications.

Controlled rectifiers are critical in many industrial settings. Common applications include:

• DC motor drives for variable speed control
• Adjustable DC power supplies
• Advanced battery charging circuits
• Industrial processes like electroplating and metal processing

Rectifier Filtering and DC Smoothing

The process of rectification converts AC to DC, but the output from a basic rectifier is not a perfectly flat line. It is a pulsating DC voltage that still contains significant AC variations, known as ripple. For most electronics, this raw output is unusable. This section explains why filtering is essential and explores the common methods used to achieve a stable dc output.

The Need for Filtering

A simple rectifier provides a pulsating DC signal. This signal is not suitable for sensitive electronics. Modern devices require a smooth and constant voltage for reliable operation. The goal of filtering is to smooth out these pulses and create a stable dc output. Without proper filtering, the leftover ripple from the rectification process can cause serious problems. Supplying stable power is critical for performance and longevity.

Excessive ripple voltage is especially harmful to sensitive components like microprocessors and memory. The negative effects include:

• Component Degradation: Ripple can stress semiconductors, leading to premature failure of CPUs, GPUs, and other critical parts. Voltage spikes from ripple can exceed component limits and cause permanent damage.
• System Instability: Unstable voltage disrupts digital logic. This can cause system crashes, data corruption, and other erratic behavior in computers and storage devices.
• Performance Bottlenecks: High ripple can create data errors in high-speed connections like PCIe 5.0. It also reduces the potential for overclocking hardware, as users must increase voltage to maintain stability, which generates more heat.

Capacitor Filters (C-Filter)

The capacitor filter, or C-filter, is the most common and straightforward method for smoothing the output of a rectifier. This simple rectifier circuit places a capacitor in parallel with the load. The capacitor acts like a small, fast-acting reservoir. It charges up when the rectifier voltage is high and then slowly discharges to the load when the rectifier voltage drops. This action fills in the "valleys" between the DC pulses, significantly reducing ripple and producing a more stable dc output.

Engineers use a specific formula to select the right capacitor for a power supply. The formula helps determine the capacitance (C) needed to achieve a desired ripple voltage.

C = I / (2 x f x Vpp)

In this formula, I is the load current, f is the input AC frequency, and Vpp is the maximum acceptable peak-to-peak ripple voltage. For example, a power supply with a 2 Ampere load current, a 50 Hz frequency, and a target ripple of 1 Volt would need a 20,000 microFarad capacitor. This calculation is a key step in designing an effective rectifier circuit for proper rectification.

Inductor Filters (L-Section)

An inductor filter uses an inductor in series with the rectifier and the load. An inductor is a coil of wire that has a unique property: it opposes any change in the current flowing through it. When the current from the rectifier tries to increase, the inductor resists the change. When the current tries to decrease, the inductor releases stored energy to keep the current flowing.

This behavior smooths out the current, which in turn helps create a stable dc output. This type of filter is very effective, especially in a high-current power supply. The process of rectification is made more effective with this filtering stage. While less common than capacitor filters in low-power applications, the inductor filter is a valuable tool in a rectifier circuit designed for industrial use. The final rectification result is a much cleaner DC signal.

Pi-Section Filters (CLC)

The Pi-section filter, also known as a CLC filter, offers the highest level of ripple reduction. It combines the strengths of both capacitor and inductor filters. The name "Pi-filter" comes from its circuit diagram, which looks like the Greek letter Pi (π). This filter is the preferred choice for applications that demand an exceptionally smooth and stable dc output. It is an efficient filter for removing unwanted AC ripple from a bridge rectifier.

The Pi-filter uses a multi-stage process to clean the pulsating DC from a rectifier. This advanced approach results in a very small ripple. The filtering happens in three distinct steps:

1. First Capacitor (C1): The first capacitor is connected in parallel with the rectifier output. It bypasses the majority of the AC ripple component to the ground due to its low impedance to AC.
2. Inductor (L): The current then flows through a series inductor. The inductor blocks any remaining AC ripple by resisting changes in current flow.
3. Second Capacitor (C2): A final capacitor is placed in parallel with the load. It filters the signal one last time, smoothing out the smallest variations to produce a nearly perfect stable dc output.

This multi-stage design makes the Pi-filter significantly more effective than a simple capacitor filter. The combination of a shunt capacitor and an L-section works together to achieve an extremely low voltage ripple using just three passive components.

The Pi-filter provides several key advantages for any rectifier circuit. It offers excellent ripple reduction, which is a major benefit over other filter types. This design also produces a high output voltage with minimal current drain. A very small voltage drop occurs at the output, contributing to its overall effectiveness. For sensitive electronics that cannot tolerate voltage fluctuations, the Pi-filter provides the clean and stable dc output necessary for reliable operation. This makes it a superior option for powering high-performance systems that use a rectifier. The advanced filtering ensures the rectifier delivers power suitable for the most demanding tasks.

Selecting the Right Rectifier

Choosing the correct rectifier involves more than just picking a circuit. Engineers must carefully evaluate several factors to ensure the power supply is efficient, reliable, and cost-effective. A proper rectifier design depends on understanding the specific needs of the application. This section guides you through the critical criteria for selecting the best rectifier components for your project.

Key Selection Criteria

The performance of a power supply starts with its rectifier components. Selecting the right rectifier diodes is a crucial first step. Engineers consider three primary characteristics to match the diode to the circuit's demands.

Voltage and Current Ratings

The most fundamental characteristics of rectifier diodes are their voltage and current ratings. These specifications determine if a diode can handle the electrical load without failing.

• Forward Current (If): This is the maximum continuous current the diode can safely conduct in the forward-biased direction. Exceeding this rating will cause the diode to overheat and fail.
• Peak Inverse Voltage (PIV): This rating indicates the maximum reverse-bias voltage the diode can block before breaking down. The PIV of the selected rectifier diodes must be higher than the peak voltage they will experience in the circuit.

Operating Frequency

The speed of the incoming AC signal, or its frequency, heavily influences the choice of rectifier diodes. Standard rectifier diodes work well for low-frequency applications like mains power (50/60 Hz). However, high-frequency systems, such as switch-mode power supplies (SMPS), require special rectifier diodes. These diodes must be able to switch on and off very quickly to keep up with the rapid AC cycles. Using a slow diode in a high-frequency rectifier design leads to significant power loss and heat.

Reverse Recovery Time (Trr)

Reverse Recovery Time (Trr) is one of the most important characteristics for high-frequency applications. It measures the time a diode takes to stop conducting when the voltage switches from forward to reverse bias.

A diode does not stop conducting instantly. For a brief moment, a small reverse current flows. A shorter Trr means the diode switches faster, which is critical for efficiency.

A long Trr causes switching losses, where power is wasted as heat each time the diode turns off. For this reason, rectifier diodes with a low Trr are essential for an efficient high-frequency rectifier.

Comparison Table: Rectifier Types

Different types of rectifiers offer distinct trade-offs between performance and cost. The full-wave bridge rectifier is often the most balanced choice, but other designs have their place. Bridge rectifiers are generally more cost-effective because they eliminate the need for a special center-tapped transformer, which can be larger and more expensive.

This table compares the main rectifier configurations based on key metrics.

Modern Diode Technologies

Advances in semiconductor technology have produced specialized rectifier diodes with superior characteristics. These modern options enable more efficient and compact rectifier design, especially for demanding applications.

Schottky Diodes

Schottky rectifier diodes are high-performance components known for their exceptional switching speed. Unlike a standard diode with a P-N semiconductor junction, a Schottky diode uses a metal-semiconductor junction. This unique structure gives it two key advantages.

1. Low Forward Voltage Drop (Vf): A Schottky diode has a very low Vf (typically 0.15V to 0.45V). This is much lower than the 0.7V to 1V drop of standard silicon rectifier diodes. This lower voltage drop significantly reduces power loss, making the rectifier more efficient.
2. Extremely Fast Switching: Schottky rectifier diodes have a near-zero reverse recovery time. This makes them the ideal choice for very high-frequency power supplies where minimizing switching losses is critical.

Fast Recovery Diodes

Fast recovery rectifier diodes are a special type of P-N junction diode engineered to have a very low reverse recovery time (Trr). While not as fast as Schottky diodes, they offer a significant improvement over standard rectifier diodes. They provide a good balance between performance and cost. These rectifier diodes are commonly used in applications where switching speeds are too high for standard diodes but where the high leakage current of a Schottky diode might be a problem.

Component Considerations

Selecting the right circuit is only part of the design process. Engineers must also choose the physical rectifier components that will make up the final assembly. The transformer and the packaging of the rectifier diodes are two critical considerations that directly impact the performance and manufacturability of the rectifier.

Rectifier Transformers

A transformer is a key partner to a rectifier in many power supply designs. Its primary job is to change the AC voltage level before rectification occurs. A dedicated rectifier transformer has special design features to handle the unique electrical stresses created by the rectifier diodes.

The current drawn by rectifier diodes is not a smooth sine wave. It occurs in short, high-current pulses. A standard transformer may overheat under these conditions. Rectifier transformers are built to handle these pulsating loads effectively. They often have a more robust construction and better thermal management. Some designs include specific features for certain rectifier types:

• Center-Tapped Windings: These are necessary for center-tapped full-wave rectifier circuits. The transformer provides the essential midpoint connection.
• Multiple Secondary Windings: A single transformer can provide several different AC voltages. Each voltage can feed a separate rectifier to create multiple DC outputs.

The transformer's voltage rating directly affects the Peak Inverse Voltage (PIV) that the rectifier diodes must endure. A proper transformer selection ensures the rectifier diodes operate safely within their specified limits.

Packaging: THT vs. SMD

Rectifier diodes come in two main package types. The choice between them depends on the power level, manufacturing process, and available space.

THT (Through-Hole Technology): These rectifier diodes have long metal leads. The leads are inserted through holes in the printed circuit board (PCB) and soldered on the other side.

SMD (Surface-Mount Device): These rectifier diodes are much smaller and have no long leads. They are placed directly on the surface of the PCB and soldered in place by automated machines.

Each packaging style offers distinct advantages for a rectifier design.

For example, a powerful industrial rectifier will likely use large THT rectifier diodes because they can handle more current and dissipate heat better. In contrast, the tiny charger for a smartphone uses SMD rectifier diodes to make the final product as small as possible. The physical package of the rectifier diodes is a fundamental choice in modern electronic design.

Rectifier Applications in 2025

Rectifiers are the unseen workhorses powering the modern world. Their applications span countless industries, from the smallest consumer gadgets to massive industrial machinery. Understanding these diverse applications reveals the true importance of AC to DC conversion. The following sections explore some of the most significant applications of rectifiers in 2025.

Consumer Electronics

Nearly every piece of consumer electronics in a home relies on a rectifier. Televisions, computers, and game consoles all contain an internal power supply to convert household AC power into the stable DC voltage needed for their sensitive components.

In modern OLED TVs, a bridge rectifier is a critical part of the Switched-Mode Power Supply (SMPS). It performs the initial conversion of AC wall power into a high-voltage DC signal, often between 130V and 300V. This DC voltage then powers the rest of the TV's complex electronics.

The evolution of charging technology also highlights new applications. Modern USB-C Power Delivery (PD) chargers use an advanced technique called Synchronous Rectification. This method replaces standard diodes with actively controlled switches for higher efficiency, which is essential for fast-charging devices.

Automotive Systems

Automotive applications for rectifiers are split between traditional and electric vehicles. In a conventional car with an internal combustion engine, the alternator generates AC power as it spins. A rectifier assembly inside the alternator converts this AC to DC to charge the battery and run the vehicle's electrical systems. This rectifier also prevents the battery from discharging back into the alternator when the engine is off.

In the growing Electric Vehicle (EV) market, high-power rectifiers are essential. On-board chargers and DC fast-charging stations use them to convert AC power from the grid into the high-voltage DC needed to charge the EV's battery pack. These advanced rectifier systems can achieve efficiencies up to 96% and can be linked together to deliver 360kW or more, enabling rapid charging.

Industrial Power and Drives

Industrial settings present some of the most demanding applications. Heavy-duty equipment requires robust and controllable power. Arc welding is a perfect example. Welding machines use a powerful rectifier to turn high-current AC into smooth DC. This creates a stable arc for clean, strong welds. Many advanced welders use a controlled rectifier with thyristors (SCRs). This specific application allows operators to precisely adjust the output current for different materials and processes. These industrial applications of rectifiers are fundamental to modern manufacturing. There are many other rectifier diode applications in industrial settings.

Rectifier Diode Applications in Telecom

The telecommunications industry depends on a constant, reliable supply of DC power. Rectifiers are the core components that provide this power. Their applications range from large data centers to the thousands of base stations that form the 5G network. These critical applications demand exceptional efficiency and unwavering reliability to keep communication channels open.

The rollout of 5G technology has created new challenges for power systems. 5G base stations require more power in smaller spaces, driving the need for highly efficient rectifiers.

• Modern rectifier modules for 5G applications achieve over 97% efficiency.
• Top-tier designs push this figure to 98% or higher.
• A key power density benchmark for these applications is 400 kW/m² for telecom cabinets.

To meet these targets, engineers use advanced wide bandgap semiconductors. Materials like Gallium Nitride (GaN) and Silicon Carbide (SiC) enable these high-performance applications. GaN, for instance, offers about 20% higher power density than SiC, making it perfect for compact telecom applications.

Reliability is just as important as efficiency in telecom applications. A power failure at a data center or cell tower can disrupt service for thousands of users.

To prevent this, engineers design robust DC rectifier systems with multiple layers of protection. These high-reliability applications often include:

• Redundancy: Systems have backup rectifiers or batteries. These components take over instantly if a primary unit fails, ensuring continuous power.
• Monitoring and Control: Advanced systems constantly check performance. They detect problems early, allowing for maintenance before a failure occurs. This is one of the most vital applications of rectifiers in maintaining network uptime.

These features are essential applications for ensuring the stability of our communication infrastructure. The specific rectifier diode applications in telecom focus on maximizing uptime and efficiency. These advanced applications demonstrate the evolving role of rectifiers in a connected world.

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Understanding what is a rectifier is key to modern electronics. A rectifier is the cornerstone of power conversion, enabling the essential ac to dc conversion that powers our world. Engineers choose from simple designs like the half-wave rectifier to the more efficient full-wave rectifier. The best rectifier for any of the many applications depends on specific power conversion needs. The future of rectification and power conversion is bright. New materials improve the ac to dc conversion process for countless applications.

Future rectifier designs will see major efficiency gains from these applications.

• Gallium Nitride (GaN) reduces both conduction and switching losses.
• Its high electron mobility allows for faster, more efficient power conversion.
• This improved rectification is vital for next-generation electronics applications.

The evolution of the rectifier continues to shape our technological landscape, with new applications for this fundamental conversion and rectification process emerging constantly. These applications drive innovation in power conversion and rectification.

FAQ

What is the main job of a rectifier?

A rectifier's primary function is the conversion of alternating current (AC) to direct current (DC). It acts as a one-way gate for electricity. This process, called rectification, is fundamental for powering nearly all electronic devices.

Why is a bridge rectifier so common?

The bridge rectifier is popular because of its high efficiency and cost-effectiveness. It uses the entire AC waveform for conversion. It also works with a standard transformer, which is less expensive than the center-tapped type required by other full-wave designs.

What does a filter do in a rectifier circuit?

A filter smooths the pulsating DC output from a rectifier. It removes the unwanted AC variations, known as ripple. This action creates a stable DC voltage, which is necessary for sensitive electronics to operate correctly and reliably.

Can a rectifier work without a transformer?

Yes, a rectifier circuit can function without a transformer. The rectifier itself only converts AC to DC. A transformer is a separate component used to step the AC voltage up or down before it reaches the rectifier.

What is the difference between a diode and an SCR?

A standard diode and an SCR (Silicon-Controlled Rectifier) both conduct current in one direction. However, an SCR includes a "gate" terminal that provides an extra layer of control.

Why are Schottky diodes used in some rectifiers?

Engineers use Schottky diodes for their high efficiency. These diodes have a very low forward voltage drop, which reduces power loss. Their extremely fast switching speed also makes them perfect for modern high-frequency power supplies, like phone chargers.

What is Peak Inverse Voltage (PIV)?

Peak Inverse Voltage (PIV) is a critical diode rating. It defines the maximum voltage a diode can withstand in the reverse direction without breaking down. A circuit designer must choose diodes with a PIV rating safely above the expected peak voltage.