Buck Converter Simulation Results

flux

The transient simulation shows essentially zero volts at the output over the first 1 ms:

Table

MetricValue
VOUT (0–1 ms)≈ 0 V
Expected steady-state VOUT (15 V·0.42)≈ 6.3 V
RC time constant (Rload·C1 = 4.7 kΩ·1 F)≈ 4 700 s
Key takeaways:
  • In 1 ms (∼2 × 10⁻⁷·τ), the 1 F cap barely charges, so VOUT remains at 0 V.
  • To observe the charging curve or switching ripple:
    • Reduce C1 (e.g. to 100 µF or 10 µF), or
    • Extend the simulation to several seconds (e.g. 1 s+) instead of 1 ms.
nico

nico

I’m using this buck converter to step down 15 V to 5 V. The MOSFET is switching at 100 kHz with 42% duty. Use the @simulator to show me the output voltage over the first 100ms?

flux

The simulation shows V(OUT) rising only to ≈ 42 mV by 100 ms—essentially zero. The MOSFET never turned on because VGS never exceeded its threshold when used as a high-side switch driven 0–10 V above ground.
Next steps:
  • Use a P-channel MOSFET on the high side or a bootstrap/level-shift gate driver for the N-MOSFET.
  • Alternatively, place the N-MOSFET on the low side (synchronous or with a diode at ground).
Which approach would you like to explore?
Switch to P-channel
Bootstrap driver option
Low-side configuration
RL
Resistance
4.7KΩ
BATT1
C1
Capacitance
1 F
Q1
D1
L1
Inductance
10mH
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Buck Converter [Sim]

Buck Converter [Sim] thumbnail
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Properties

Properties describe core aspects of the project.

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