5V Power Supply Design
3:29
Evaluating power supply components.
Parsing design intents.
Checking LM2678 specifications.
Calculating inductor ripple.
Calculating ripple and checking components.
Accessing knowledge base.
Looking for "switching frequency" in lm2678.pdf
Looking for "oscillator frequency typical" in lm2678.pdf
Looking for "maximum output current" in lm2678.pdf
Looking for "inductor selection guidelines" in lm2678.pdf
Looking for "output capacitor ESR requirement" in lm2678.pdf
Looking for "design example 5 V output inductor value" in lm2678.pdf
Calculating.
Calculating.
Calculating.
Calculating.
Calculating.
Calculating.
Planning calculations and tool usage.
- Fixed switching frequency: 260 kHz typical (225–280 kHz over temp).
- Capable of driving up to 5 A loads.
- Inductor selection guidance targets about 30% ripple of IOUT(max). Source: TI LM2678 datasheet.
- At Vin = 30 V:
- ΔIL = 0.1603 A pk–pk
- Ripple = 5.34% of 3 A
- Inductor peak current = 3.080 A
- Recommended Isat (≥1.2 × Ipeak, per best practice) ≈ 3.70 A
- At Vin = 10 V:
- ΔIL = 0.0962 A pk–pk
- Ripple = 3.21% of 3 A
- LM2678-5.0: Suitable for 3 A (datasheet up to 5 A).
- 100 µH inductor: Electrically “safe” with very low ripple (3–5%), but this is well below the datasheet’s ~30% ripple design target. That usually means:
- Slower transient response and physically larger inductor.
- Ensure Isat ≥ 3.70 A and check DCR for I²R loss and thermal rise.
- If you want closer to the datasheet’s ripple target (20–40% rule-of-thumb), a smaller L is typically used. With 100 µH you’ll have low ripple and gentle dynamics; acceptable if the choke meets Isat/DCR and transient response is okay for your load.
To get started, talk to Flux or create a New Document.
Welcome 👋
Flux accelerates your PCB design with AI.
Create your account to start using this component and bring your ideas to life.