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What are some tips for modeling optocouplers for Pspice?
5 P# d) @; }' s% {- l& YThough Model Editor does not provide a template for either an optocoupler or for a phototransistor, it can beused create components of these models. For example,you can use Model Editor to model the electricalcharacteristics of the input LED of an optocoupler.
! q+ T0 q2 E3 G- [+ uIn the case of the optocoupler，you need to create a model for a LED input，and also for a single BJTphototransistor output optocoupler.4 W' F& m( K, N4 G4 I) r8 M
1.LED# R# ^4 j5 v& m: H/ j; v1 n
To model LED input, fit the forward current vs. voltage curve of the LED, and the LED capacitance curve toa PSpice diode. These curves are available in datasheets.6 |- k: u* w9 K2 I
2.CTR curve fit
9 ~9 Q* U( a! F4 @Use Mathcad or Excel to fit the CTR curve to a polynomial. A polynomial which may work is of the formA*exp(B+Cx).* t' H7 G% V4 y% T5 A [
In the sample model shown below, the Gpcg source models the CTR curve. In this case, two regions were fitseparately, the region If<=10mA and the region If>10mA, where If is the LED forward current. The outputcurrent of the Gpcg source is the phototransistor collector current.* w: e/ M+ t* ]% Y
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发表于 2021-3-16 10:09
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