Step-by-step method
- Always check units, prefixes and order of magnitude.
- Estimate duty cycle, input current, power and loss for a buck or boost converter.
- Compare the result with temperature, tolerances and real conditions.
Buck and boost converter
Estimate duty cycle, input current, power and loss for a buck or boost converter.
Calculate
Ideal duty cycle
—
Input current
—
Input power
—
Loss
—
Mistakes to avoid
- Always check units, prefixes and order of magnitude.
- Do not use an ideal result without margin or a datasheet check.
- Compare the result with temperature, tolerances and real conditions.
Component selection
Choose a controller rated for Vin/Vout and peak current; always follow its datasheet and reference design.
Worked example
A 12 V to 5 V buck delivering 2 A at 90% draws about 0.93 A and loses about 1.11 W.
Limits and safety
The averaged model does not size the inductor, ripple, switches, diode, capacitors, compensation or current limit.
Technical sources
Do not use an ideal result without margin or a datasheet check.