On Sun, Apr 6, 2025 at 01:19 PM, Christopher Paul wrote:

I am still getting the following error messages when I run your file.:

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u1:_u1_u12:dd1: Emission coefficient, N=4.83179e-313, too small, limited to 0.1

u1:_u1_u11:dd1: Emission coefficient, N=4.83179e-313, too small, limited to 0.1

u2:_u1_u12:dd1: Emission coefficient, N=4.83179e-313, too small, limited to 0.1

u2:_u1_u11:dd1: Emission coefficient, N=4.83179e-313, too small, limited to 0.1

Those error messages will continue.? It concerns a diode parameter N, which had been set to an extremely small value.? Until recently, that was accepted by LTspice despite being unreasonably small.? In newer versions, LTspice complains and limits it to >= 0.1.

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Why was the model's N set to such a small value?? Sometimes, the people who make SPICE models use diodes to help construct other elements that have voltage dependencies but are not actual diodes.? I have seen this done to make voltage-dependent capacitors.

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One might argue that Analog Device's decision to limit N was an unwise choice, given the fact that many SPICE models over time have been built that way.? But now we are stuck with it.

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I am unfamiliar with the round(I(RL2)*1e4)/1e4 instruction you used and can’t find a reference to it in my Help instructions.

Are you sure?? The "round()" function is documented in a few places, including the Help pages for Waveform Arithmetic, for B-sources, and for the .PARAM command.? It is like it sounds; it rounds a real number to the closest integer.

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Here, it is being used to truncate a number to having fewer significant digits.? Multiply the number by 1e4. find the nearest integer, then divide it by 1e4.? All digits past the 4th after the decimal point are turned to zeros, and thus are omitted.

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Andy

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