I'm simulating a circuit with a on-semi 1SMB5914BT3G zener-diode (3.6V) using LTSpice. If I increase the temperature from 27°C to 47°C the zener voltage increases from 3.6V to 4.26V @100mA.

PSpice Model from onsemi

Isn't that far too much? If I have a look at the datasheet page 4 I would expect approx. -1.5mV/°C. Is there an error in the spice model or am I using it wrong?

Simulating 1SMB5914BT3G with LTSpice

  • \$\begingroup\$ Sounds too high. Who made the model? \$\endgroup\$
    – winny
    Aug 7, 2017 at 14:40
  • \$\begingroup\$ @winny It's from the official onsemi website and has this in the header "* Model Generated by MODPEX * Copyright(c) Symmetry Design Systems" \$\endgroup\$
    – Andy
    Aug 7, 2017 at 17:56

1 Answer 1


Run the model with a current source as shown below and you will likely get the results you expect.


simulate this circuit – Schematic created using CircuitLab

  • \$\begingroup\$ This doesn't even use the linked spice model, right? \$\endgroup\$
    – Andy
    Aug 8, 2017 at 17:32

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