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Round Robin (RR) scheduling is a fundamental algorithm used in both computer science and sports event planning. Its simplicity, fairness, and deterministic behavior make it one of the most studied and implemented scheduling strategies. In this blog, we’ll explore the concept of Round Robin scheduling in depth, explain how it works, provide calculation methods, and even show how to create your own schedule using Excel.

1. What Is Round Robin Scheduling?

Round Robin scheduling is a method of assigning time slots or turns to entities (processes, players, or tasks) in a cyclic and repeated manner. Each participant is treated equally and given a fixed time slice or opportunity before the turn moves to the next.

In operating systems, it’s a preemptive CPU scheduling algorithm that allocates CPU time to each process in a queue for a set “time quantum” or “time slice,” then cycles to the next.

In sports tournaments, especially leagues and competitions, it ensures each team or player competes with every other participant an equal number of times.

2. How Does Round Robin Scheduling Work?

In CPU Scheduling:

· A process queue is maintained in FIFO (First In, First Out) order.

· Each process is given a time slice (quantum).

· If the process finishes before the time is up, it leaves the queue.

· If not, it goes to the back of the queue and waits for its next turn.

· This continues until all processes are completed.

In Tournaments:

· Every participant plays against all others.

· The number of rounds is n-1 for an even number of participants and n for odd.

· Scheduling ensures fairness and balance across rounds. 

3. What Is Round Robin CPU Scheduling Algorithm?

Round Robin is a preemptive scheduling algorithm. Key characteristics:

· Fairness: Each process gets an equal opportunity.

· Preemption: Tasks are interrupted if not completed within the quantum.

· Predictability: Regular time intervals for task execution.

Ideal Use Cases:

· Time-sharing systems

· Interactive systems (where responsiveness matters)

4. Key Terms in Round Robin Scheduling

· Burst Time (BT): Time required by a process for execution.

· Arrival Time (AT): Time when a process enters the queue.

· Completion Time (CT): Time when a process finishes execution.

· Turnaround Time (TAT): TAT = CT - AT

· Waiting Time (WT): WT = TAT - BT

· Response Time (RT): Time from arrival to first execution.

5. How to Calculate Round Robin Scheduling Metrics

Let’s assume:

· 4 processes: P1, P2, P3, P4

· Time Quantum: 4 units

Step-by-Step Metrics Calculation:

A. Completion Time (CT)

Track the time when each process finishes execution during the Gantt chart traversal.

B. Turnaround Time (TAT)

TAT = Completion Time - Arrival Time

C. Waiting Time (WT)

WT = Turnaround Time - Burst Time

D. Response Time (RT)

RT = Time of first CPU allocation - Arrival Time

E. Average Times

Add up individual times and divide by the number of processes:

· Avg TAT = ΣTAT / n

· Avg WT = ΣWT / n

6. How to Draw a Gantt Chart for Round Robin

A Gantt chart visually shows process execution over time:

Example (Quantum = 4):

| P1 | P2 | P3 | P4 | P1 | P3 | ...

0    4    8    12   16   18   ...

This helps determine when each process was executed, useful for computing CT, RT, etc.

7. How to Solve a Round Robin Scheduling Problem

Steps:

1. List all processes with arrival and burst times.

2. Choose a time quantum.

3. Create a queue and follow the RR algorithm.

4. Use a table or Gantt chart to trace execution.

5. Calculate CT, TAT, WT, RT.

6. Derive averages.

8. How to Create a Round Robin Schedule (Tournament Context)

For n teams:

· Each team plays once per round.

· For even n: use circle method — fix one team and rotate others.

· For odd n: add a dummy "BYE" team to make it even.

Sample 4-Team Schedule (Even):

Round 1: A vs D, B vs CRound 2: A vs C, D vs BRound 3: A vs B, C vs D

9. How to Create a Round Robin Schedule in Excel

Steps:

1. Create a table with team names in both rows and columns.

2. Mark matchups where row ≠ column.

3. Use conditional formatting or macros to automate match distribution by round.

4. For tournament play, hide duplicate pairings (e.g., A vs B and B vs A).

Alternatively, use Excel formulas or VBA scripts to generate schedule rotation logic.

10. FAQs on Round Robin Scheduling

Q1: What is the main disadvantage of Round Robin?
A: If the quantum is too small, context switching overhead becomes high; if too large, it behaves like FCFS.

Q2: What is the best time quantum?
A: It depends on the system—must balance between responsiveness and overhead.

Q3: Can Round Robin handle priorities?
A: Traditional RR ignores priorities; a variant like Priority Round Robin is used when priorities are needed.

Q4: What if all processes have different arrival times?
A: The scheduler waits for process arrival and adjusts the ready queue dynamically.

Conclusion

Round Robin scheduling is versatile, fair, and easy to implement—ideal for multitasking operating systems and tournament design alike. Understanding how it works and how to calculate key metrics helps developers, analysts, and organizers build efficient schedules whether on a CPU or a soccer field.

By learning how to visualize with Gantt charts, compute performance metrics, and automate tournament schedules in Excel, you’re well-equipped to handle any Round Robin scheduling challenge.

Designed for Enhanced Performance in Automotive Circuits with Compact 1210 and 1812 SMD Packages

Riverside, California – May 13, 2025 – Bourns, Inc., a leading manufacturer and supplier of power, protection, and sensing components, has announced the release of two new automotive-grade multilayer varistor (MLV) product series: the Bourns® BVRA1210 and BVRA1812. These new components meet AEC-Q200 standards and are specifically engineered to meet the stringent requirements of modern automotive electronic systems, offering superior protection against voltage transients and electrical surges.

The BVRA series features low-voltage multilayer varistor technology with advanced energy distribution and optimized power dissipation capabilities, delivering outstanding transient energy absorption performance. These characteristics make them ideal for safeguarding sensitive automotive electronics against damaging surge events.

Engineered in compliance with the IEC 61000-4-5 standard, the BVRA1210 and BVRA1812 provide effective overvoltage protection, helping automotive designers protect critical components from high-energy transient voltage events such as inductive load switching or lightning-induced surges.

Key features of the new BVRA series include:

· Ultra-fast response time of less than 1.0 nanosecond, enabling rapid clamping during surge conditions

· Stable leakage current performance, ensuring consistent overvoltage protection over time

· Wide operating voltage range, covering 11 VDC to 100 VDC, to accommodate diverse automotive applications

· Compact surface-mount packages: EIA 1210 and 1812 footprints allow for high-density PCB layouts

· Insulation coating for enhanced reliability and easier integration in automotive systems

The BVRA1210 and BVRA1812 are fully RoHS compliant and lead-free, aligning with environmental and industry sustainability standards outlined in RoHS Directive 2015/863 (dated March 31, 2015, and its annexes).

The new Bourns® BVRA series is now available through Bourns' authorized distributors worldwide. For detailed product specifications and application guidance, visit the official product page at bourns.com

Five New Reference Designs Showcase the Capabilities of InnoSwitch™3-AQ Flyback ICs in Wide-Creepage InSOP™-28G Packages

Nuremberg, Germany – PCIM 2025, May 2025 – Power Integrations (Nasdaq: POWI), a leading innovator in high-voltage integrated circuits for energy-efficient power conversion, today announced five new reference designs tailored for 800V electric vehicle (EV) systems. These designs are based on the company’s 1700V-rated InnoSwitch™3-AQ flyback switcher ICs, optimized for demanding automotive applications such as DC-DC bus conversion, inverter emergency power supplies, battery management systems, and auxiliary power supplies.

All five designs leverage Power Integrations' proprietary InSOP™-28G packaging, engineered for wide creepage distances and enhanced high-voltage safety. This package supports up to 1000VDC on the primary side and provides compliant creepage and clearance distances for Pollution Degree 2 environments, eliminating the need for conformal coating and simplifying system certification and manufacturing.

Enhanced Safety and Integration for Next-Generation EVs

According to Mike Stroka, Product Marketing Engineer at Power Integrations, “The InSOP™-28G package offers a 5.1 mm creepage distance between drain and source pins, aligning with stringent safety and reliability requirements in high-voltage automotive applications. By eliminating the need for conformal coating, manufacturers can streamline production and reduce associated costs and qualification steps.”

Each InnoSwitch3-AQ IC integrates a 1700V silicon carbide (SiC) primary switch, delivering high efficiency and robustness ideal for 800V EV platforms. These ICs help engineers improve system performance and reliability while reducing PCB space and component count.

Overview of New Reference Designs

All designs use InnoSwitch3-AQ constant-voltage/constant-current flyback ICs and are available for download from power.com. The reference designs include:

· RDK-994Q: A 35W ultra-thin isolated power supply suitable for traction inverter gate drivers or emergency power systems. Operates from 40–1000VDC input and outputs 24V.

· RDK-1039Q: An 18W compact design utilizing a planar transformer, ideal for traction inverter gate drivers or backup power.

· RDK-1054Q: A high-power 120W planar transformer design aimed at minimizing or eliminating the need for bulky 12V lead-acid batteries.

· DER-1030Q: A 20W four-output design including a 24.75V emergency power rail and three 25.5V outputs for gate driver circuits.

· DER-1045Q: A 16W four-output design delivering one 14V emergency rail and three gate drive outputs with ±18V/-5V voltages.

Key Features and Performance Advantages

· High Output Power: Up to 120W from a single compact IC.

· High Integration: Reduces BOM count by up to 50%, saving board space and simplifying sourcing.

· Low Start-Up Voltage: Starts from as low as 30V, eliminating the need for external circuitry—a key requirement for functional safety.

· Efficiency: Achieves over 91% efficiency using a DCM/CCM flyback topology with synchronous rectification and valley switching.

· Comprehensive Protection: Includes input undervoltage lockout, output overvoltage protection, overcurrent limiting, and ultra-low no-load power consumption (<15mW).

Availability and Pricing

The 1700V InnoSwitch3-AQ ICs are available now, priced at $6 each in 10,000-unit quantities. Reference design kits range from $50 to $100. Engineers can enter to win a kit at pages.power.com/rev-up. For purchasing or additional technical information, contact Power Integrations’ sales representatives or authorized global distributors such as DigiKey, Newark, Mouser, and RS Components.