Proteus error : time step too small, MOSFET circuit

Thread Starter

Hanif Prasetyo

Joined Apr 22, 2017
3
I was trying to combine two side switch using MOSFET. both using IRF530 as the high and low side switch. It work perfectly when I used 1 seven-segment, but it began to throw error after i tried to have 2 additional seven-segments.

[SPICE] DELMIN increased to 1.11022e-016 due to lack of time percision
[SPICE] transient GMIN stepping at time =0.501998
[SPICE] TRAN: Time step too small; timestep = 1.38778e-017: trouble with node ...
I have the circuit pic attached.
I don't have a good electrical engineering background. but I guess the circuit is wrong?
Please, help.
 

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absf

Joined Dec 29, 2010
1,943
Though I am not sure what you're trying to accomplish. But I see there is something not right in your schematic.

proteus circuit_rotated.png
Why are Q2, Q10 and Q12 emitters connected differently?
What are the 4 DC "COM" voltages you used to switch 2n2222 and the IRF530 at the bottom?

Allen
 

Thread Starter

Hanif Prasetyo

Joined Apr 22, 2017
3
Thanks for the quick answer, Allen.
The Q2, Q10, and Q12 emitters are supposed to be grounded. I used this (image attached) circuit as reference.
I got bad wiring there, at Q2. i've fixed it but still get the same error.

The DC COMs bellow are 5V from microcontroller.
The whole point of this circuit is to make switch for seven-segment's 12v power supply.
It's more like a driver circuit from 5v to 12v (?)
I've used relay as the switch before, but i need more "responsive" switch, as the mechanical switch at relays are too slow. so i got the idea to used MOSFET. there are low-side switch and high-side switch circuits out there, but i cant find circuit witch using both. is there any other way do do this?
 

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absf

Joined Dec 29, 2010
1,943
i've fixed it but still get the same error.

The DC COMs bellow are 5V from microcontroller.
The whole point of this circuit is to make switch for seven-segment's 12v power supply.
It's more like a driver circuit from 5v to 12v (?)
I've used relay as the switch before, but i need more "responsive" switch, as the mechanical switch at relays are too slow. so i got the idea to used MOSFET. there are low-side switch and high-side switch circuits out there, but i cant find circuit witch using both. is there any other way do do this?
I do it with Proteus 7.8 and this is what I got...

7seg mosfet disp.PNG
1. SW 1 and 9 has to be OFF in order to get display.
2. There is about 5V across the LED. Is that OK with your diaplay?
3. The current through each mosfet is about 3A. Wouldn't that be too high for your display?

I think you need some Current Limiter resistors on the display paths.

Allen
 

Thread Starter

Hanif Prasetyo

Joined Apr 22, 2017
3
Perhaps, the problem is with my Proteus 8. I imitate the whole schema and still throw the same error. What I've discovered is, if I trigger the sw1 and sw9 slowly(with delay around 4 seconds), it won't throw error.

I need to confirm, is this a simulation error and will work fine in real circuit, isn't it?

About the display is 12V 3A 4inch seven-segment. I think it's 3A tolerate.
 

absf

Joined Dec 29, 2010
1,943
If you dont try it out, how are you going to know?

A simulator is a simulator, it simulates and let you have an idea of how your circuit would behave.

But in the real world, I normally use PNP BJT on the top and NPN BJT at the bottom. There are also transistor arrays like ULN2003 or ULN2804 which has 7 or 8 darlington pairs inside the chip that would save you some PCB real estates.

Allen
 
I was trying to combine two side switch using MOSFET. both using IRF530 as the high and low side switch. It work perfectly when I used 1 seven-segment, but it began to throw error after i tried to have 2 additional seven-segments.

[SPICE] DELMIN increased to 1.11022e-016 due to lack of time percision
[SPICE] transient GMIN stepping at time =0.501998
[SPICE] TRAN: Time step too small; timestep = 1.38778e-017: trouble with node ...
I have the circuit pic attached.
I don't have a good electrical engineering background. but I guess the circuit is wrong?
Please, help.
Hello! Sometimes the source of this error is related to model indetermination during simulation. Use PULL-UP and PULL-DOWN resistors whenever you work with transistors or digital circuits. With this, the simulator can assume an initial numerical value.
 

WBahn

Joined Mar 31, 2012
25,732
I was trying to combine two side switch using MOSFET. both using IRF530 as the high and low side switch. It work perfectly when I used 1 seven-segment, but it began to throw error after i tried to have 2 additional seven-segments.

[SPICE] DELMIN increased to 1.11022e-016 due to lack of time percision
[SPICE] transient GMIN stepping at time =0.501998
[SPICE] TRAN: Time step too small; timestep = 1.38778e-017: trouble with node ...
You cut out the good stuff. Which node is it having trouble with.

Timestep too small errors often occur if you have an ideal voltage/current source that changes too quickly (like a step change). Put a slower edge on it.
 

Yawkong

Joined Jan 31, 2018
1
hey guys. I designed a mosfet driver circuit and its giving me the same problem "timestep error problem". I need help. the mosfets are IRF840 with two IR2112 MOSFET DRIVER. i need help please. it is urgent please. O have attached my circuit diagram.
 

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