Hot-swap inrush and SOA
Linear-ramp pass-device stress compared with user-entered single-pulse SOA points.
Development preview. Check the assumptions below before relying on a result. Calculations run in your browser.
How it calculates
Assumptions
- The entered SOA curve must be for a pulse at least as long as the ramp. Interpolation is logarithmic between entered points.
- Linear thermal derating uses (Tjmax − Tcase)/(Tjmax − Tref); verify the manufacturer permits this rule.
- Below the lowest entered VDS, no SOA evaluation is performed. A current-limited load is assumed throughout the ramp.
Worked example
These are the calculator's default inputs. Change any input above to recalculate.
Inputs
- Supply voltage
- 24 V
- Load capacitance
- 0.002 F
- Output rise time / SOA pulse duration
- 0.02 s
- Load current during ramp
- 0.1 A
- Case temperature
- 50 °C
- SOA reference case temperature
- 25 °C
- Maximum junction temperature
- 150 °C
- SOA VDS coordinates at this pulse duration
- 1, 10, 30, 60 V
- SOA allowed-current coordinates
- 20, 10, 2, 0.5 A
Results
- Total pass current
- 2.5 A
- Minimum interpolated SOA current margin
- 0.887464
- Capacitor current
- 2.4 A
- Initial pass-device power
- 60 W
- Start-up pass energy
- 0.6 J
- Allowed current at initial VDS
- 2.21866 A