What should I do with the 4th pin of 2N2907AHR transistor with UB package type?

[JazzJackRabbit]

My question is about the 4th pin of 2N2907AHR transistor with UB package type.

https://www.st.com/resource/en/datasheet/2n2907ahr.pdf

What should I do with the 4th pin?

Because of regulations and standards, I cannot let it flow. 

[Peter BENSCH]

It is connected to the lid on top, which acts as a shielding. Depending on the current circuitry you connect it to e.g. either GND or VCC.

Does it answer your question?

/Peter

[JazzJackRabbit]

Thanks a lot Peter.

Yes it answers my question. I need some clarification :)

1. If it is for shielding isn't it always should be connected to GND?

What are the conditions that I should connect the 4th pin to whether Vcc or GND?

I use 2N2907AHR as a switch e.g., the picture below. Where should I connect it?

2.

I could not find 2N2907AHR and 2N2222AHR  PSpice model, and I am using the default 2N2907A and 2N2222A PSpice models. Can I use these models for AHR ones?

[Peter BENSCH]

Hi, JazzJackRabbit,

the original question was answered.

In terms of high frequency, it probably doesn't matter whether the lid is connected to GND or VCC as both are usually connected via some capacitance. In space applications it may depend on the radiation which connection is preferred.

If you have further questions, please open a new topic, alternatively you can login at my.st.com and ask for support and models.

Best regards

/Peter