1. What is the SMPS Transformer Equation?

The SMPS transformer equation calculates the number of turns required for the primary winding of a switch-mode power supply transformer based on input voltage, on-time, flux density change, and core effective area.

2. How Does the Calculator Work?

The calculator uses the SMPS transformer equation:

Where:

• \( V_{in} \) — Input voltage (volts)
• \( t_{on} \) — On time of switching (seconds)
• \( \Delta B \) — Flux density change (tesla)
• \( A_e \) — Effective core cross-sectional area (m²)

Explanation: The equation balances volt-seconds applied to the winding with the core's flux capacity to determine the minimum number of turns needed to prevent core saturation.

3. Importance of Turns Calculation

Details: Proper turn count ensures the transformer operates efficiently without core saturation, which can lead to excessive losses and potential failure.

4. Using the Calculator

Tips: Enter all values in the specified units. Typical ΔB values range from 0.2-0.3T for ferrite cores. A_e is usually provided in core datasheets in mm² (convert to m² by multiplying by 10^-6).

5. Frequently Asked Questions (FAQ)

Q1: What is a typical ΔB value for ferrite cores?
A: For most ferrite materials, 0.2-0.3 tesla is typical to avoid saturation while maintaining good efficiency.

Q2: How do I find A_e for my core?
A: Check the core's datasheet - it's usually listed as "effective area" or "A_e" in mm².

Q3: What affects the choice of ΔB?
A: Core material, operating frequency, temperature, and desired margin against saturation all influence ΔB selection.

Q4: Does this calculate primary or secondary turns?
A: This calculates primary turns. Secondary turns are determined by the turns ratio needed for your output voltage.

Q5: What if I get a fractional number of turns?
A: Always round up to the nearest whole number to ensure you don't under-design the winding.