Electronics · Tool
MOSFET Junction Temperature
Compute MOSFET junction temperature from drain current, RDS(on), thermal resistance, ambient temperature and duty cycle. Flags marginal and danger conditions against the configured Tj-max.
Inputs
drain_current_aRequirednumber (A)Drain Current
required · min 0.001 · max 1000 · default 5
required · min 0.001 · max 1000 · default 5
rds_on_mohmRequirednumber (mΩ)RDS(on)
required · min 0.1 · max 10000 · default 20
From the datasheet at the gate-drive voltage you use.
required · min 0.1 · max 10000 · default 20
From the datasheet at the gate-drive voltage you use.
theta_ja_c_per_wRequirednumber (°C/W)θ-JA
required · min 0.1 · max 500 · default 62
Junction-to-ambient thermal resistance — depends heavily on copper area.
required · min 0.1 · max 500 · default 62
Junction-to-ambient thermal resistance — depends heavily on copper area.
ambient_temp_cRequirednumber (°C)Ambient Temp
required · min -40 · max 125 · default 25
required · min -40 · max 125 · default 25
duty_cycleRequirednumberDuty Cycle
required · min 0.01 · max 1 · default 1
1.0 = continuous on. Use the actual on-time fraction for switched applications.
required · min 0.01 · max 1 · default 1
1.0 = continuous on. Use the actual on-time fraction for switched applications.
max_junction_temp_cRequirednumber (°C)Max Junction Temp
required · min 100 · max 200 · default 150
Datasheet Tj-max. 150 °C is typical for silicon, 175 °C for SiC.
required · min 100 · max 200 · default 150
Datasheet Tj-max. 150 °C is typical for silicon, 175 °C for SiC.
Outputs
power_dissipation_wnumber (W)Power Dissipation
temp_rise_cnumber (°C)Temperature Rise
junction_temp_cnumber (°C)Junction Temperature
headroom_cnumber (°C)Headroom
statusstringStatus
Example request
curl -X POST https://toolsamurai.com/api/v1/electronics/mosfet-thermal-junction \ -H "Authorization: Bearer sk_free_•••••••••••••••" \ -H "Content-Type: application/json" \ -d '{ "drain_current_a": 5, "rds_on_mohm": 20, "theta_ja_c_per_w": 62, "ambient_temp_c": 25, "duty_cycle": 1, "max_junction_temp_c": 150 }'
Example response
{ "ok": true, "tool": "mosfet-thermal-junction", "domain": "electronics", "version": "1.0.0", "result": { "power_dissipation_w": …, "temp_rise_c": …, "junction_temp_c": …, "headroom_c": …, "status": "…" }, "meta": { "latency_ms": …, "request_id": "req_…" } }