Problem getting LTSpice to simulate with CD4000.lib

E

eTech

Well-Known Member

• Mar 6, 2019

• #21

jsduan said:

Yes, I use the cd4093B model from Yahoo group. Could you please tell me how to set the negative power supply instead of ground?

Click to expand...

Hi

Just change the spiceline attribute values to the supply node names.
VDD 0 <<<<change this
VDD VSS <<<<to this

Make sure supply nodes VDD and VSS exist.

eT



Here's a view of the properties for the CD4093B, The SpiceModel attribute has been changed:

 

J

jsduan

New Member

• Mar 7, 2019

• #22

HI i wanna simulate this circuit. and the 4093b is used to produce the delay clock. The clock input the U4C is shown and I change the spice model. However, it still can not work.

 

E

eTech

Well-Known Member

• Mar 7, 2019

• #23

there is no matching voltage sources..

 

J

jsduan

New Member

• Mar 7, 2019

• #24

 

J

jsduan

New Member

• Mar 7, 2019

• #25

Here is the circuit I built.

 

E

eTech

Well-Known Member

• Mar 7, 2019

• #26

Post the .asc file

 

J

jsduan

New Member

• Mar 7, 2019

• #27

Thanks for your help

 

Attachments

• 3.asc

  6.1 KB · Views: 288

alec_t

Well-Known Member

Most Helpful Member

• Mar 7, 2019

• #28

The output of U3 is switching between 0V and 5V rather than between -5V and 5V, so it looks like the model needs further modifications to cope with the dual polarity supply.

 

J

jsduan

New Member

• Mar 7, 2019

• #29

Yes. I need to make it to produce between -5 to 5

 

E

eTech

Well-Known Member

• Mar 7, 2019

• #30

alec_t said:

The output of U3 is switching between 0V and 5V rather than between -5V and 5V, so it looks like the model needs further modifications to cope with the dual polarity supply.

Click to expand...

The model will produce that if the correct input voltages are used..

 

J

jsduan

New Member

• Mar 7, 2019

• #31

So could you please tell me how to solve it. In practical, the chip actually can output a -5 to 5V

 

alec_t

Well-Known Member

Most Helpful Member

• Mar 7, 2019

• #32

Get rid of V3 and label that top node as Vdd.

 

J

jsduan

New Member

• Mar 7, 2019

• #33

I tried but the output of U3 is constant which is 0 now

 

alec_t

Well-Known Member

Most Helpful Member

• Mar 7, 2019

• #34

You need to edit each 4093 symbol in your asc file as etech suggested in post #21.
Right-click on the U3 symbol. In the pop-up, change the Spice Model attribute from "VDD 0" to "VDD VSS".

 

J

jsduan

New Member

• Mar 7, 2019

• #35

 

J

jsduan

New Member

• Mar 7, 2019

• #36

I have changed the attribute but the output of U3 is this

 

alec_t

Well-Known Member

Most Helpful Member

• Mar 7, 2019

• #37

Well it's now switching from 5V to -5V, so the model is working and your circuit must have another problem. Probe each part in turn to locate the section giving rise to the unwanted result.