jms_embedded
Well-known member
I'm trying to model the forward voltage of the Nexperia PMEG4010CEH Schottky diode, shown in this graph, for some circuit analysis.
The -40 C / +25 C / +85 C curves fit a model of (ideal diode in series with resistor) very well, that is, Vf = kT/q * ln(I/Is) + IR, within a few millivolts, better than I expected. But the values of R and Is change with temperature, and I'm not familiar with diode models enough to understand what's going on here and see if it matches theoretical physics / materials science, or whether there are empirical differences.
-40 C: R ~ 72 milliohms, Is ~ 0.2 nA
25 C: R ~ 103 milliohms, Is ~ 430 nA
85 C: R ~ 146 milliohms, Is ~ 35 uA
What should I expect from this kind of diode? Is the resistance likely due to the metal terminals, or the silicon, or some other phenomenon? What about Is variation?
I have a question into Nexperia about this already, but I'm curious if any of you are familiar enough with device modeling to explain this.
Nexperia posts a SPICE model (still attributed to NXP, lol) and the RS and IS numbers are similar to my 25 C fit, but I don't see temperature variation here. (But then again, I'm not that familiar with SPICE to know if I'm missing anything.)
The -40 C / +25 C / +85 C curves fit a model of (ideal diode in series with resistor) very well, that is, Vf = kT/q * ln(I/Is) + IR, within a few millivolts, better than I expected. But the values of R and Is change with temperature, and I'm not familiar with diode models enough to understand what's going on here and see if it matches theoretical physics / materials science, or whether there are empirical differences.
-40 C: R ~ 72 milliohms, Is ~ 0.2 nA
25 C: R ~ 103 milliohms, Is ~ 430 nA
85 C: R ~ 146 milliohms, Is ~ 35 uA
What should I expect from this kind of diode? Is the resistance likely due to the metal terminals, or the silicon, or some other phenomenon? What about Is variation?
I have a question into Nexperia about this already, but I'm curious if any of you are familiar enough with device modeling to explain this.
Nexperia posts a SPICE model (still attributed to NXP, lol) and the RS and IS numbers are similar to my 25 C fit, but I don't see temperature variation here. (But then again, I'm not that familiar with SPICE to know if I'm missing anything.)
Code:
*
*******************************************
*
*PMEG4010CEH
*
*NXP Semiconductors
*
*1A very low VF MEGA Schottky barrier rectifier
*
*
*
*
*IFSM = 9A @ tp = 8ms
*VF = 490mV @ IF = 1A
*
*
*
*
*
*
*
*
*
*
*Package pinning does not match Spice model pinning.
*Package: SOD123F
*
*Package Pin 1: Cathode
*Package Pin 2: Anode
*
*
*
*
*Simulator:SPICE2
*
*******************************************
*#
.SUBCKT PMEG4010CEH 1 2
*
D1 2 1 PMEG4010CEH
R1 2 1 1E+7
*
* The Resistor R1 does not reflect
* a physical device. Instead it
* improves modeling in the reverse
* mode of operation.
*
.MODEL PMEG4010CEH D
+ IS = 2.802E-7
+ N = 0.9521
+ BV = 44
+ IBV = 6E-6
+ RS = 0.1201
+ CJO = 1.288E-10
+ VJ = 0.3855
+ M = 0.4889
+ EG = 0.69
+ XTI = 2
.ENDS
*
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