Bichip LED model clipping?

QSPICE
1

Hi all,

I have something strange with a bichip LED model.
I got a spice model for a white bichip LED.The expected Vf is around 5.5V at ~40mA.

I tried to get the I/U characteristics under a quick simulation to check my .model definition.

Under Qspice, the Vf seems not able to be higher than a single chip LED type.
Under an other sw (LTspice), the same .model gave me a “relevant”/“expected” graph.

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→ Is something in Qspice limiting the Vf value for a LED ? Or a LED is always considered as a single chip model ?
→ How I can simulated a bichip under Qspice ?

Thanks a lot for your help

2

Please refer to this post to enable yourself to upload something for the community to review.
If this is .model, refer to 2nd message in this reference to copy your .model statement into forum.
Qspice Forum - New User to Basic User (File Upload) - QSPICE - Qorvo Tech Forum

3

Hi KSKelvin,

Thanks for your answer.
Sorry I missed the .model :

.model bichip D(IS=147.52E-17 N=4.2406 RS=1.5156E-6 IKF=117.28E-12)

4

Currently, a temporary solution is to add ISR=1e-308 into this model statement (a value near 0 but not 0). IKF is expected to have an effect with ISR=0 (revision history : 10/21/2023 Diode model parameter IKF is now used even if ISR is zero.). I have copied this for Mike to review.

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