Temperature Step in a .TRAN Simulation?

Any clever soul out there figured out a way to do that?

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Mon, 05 May 2014 11:49:22 -0700, Jim Thompson wrote:

Temperature Step in a .TRAN Simulation?

Any clever soul out there figured out a way to do that?

...Jim Thompson

LTSpice or regular?

I'm pretty sure you can do it with a .STEP or a .TEMP command in LTSpice.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

On Mon, 05 May 2014 13:58:50 -0500, Tim Wescott
wrote:

On Mon, 05 May 2014 11:49:22 -0700, Jim Thompson wrote:

Temperature Step in a .TRAN Simulation?

Any clever soul out there figured out a way to do that?

...Jim Thompson

LTSpice or regular?

I'm pretty sure you can do it with a .STEP or a .TEMP command in LTSpice.

..STEP isn't the same as a step in temperature _during_ the simulation
run.

..STEP simply applies a data change at the _beginning_ of a run.

I want, during a transient solution, to have a temperature change to
test a temperature-related shutdown mechanism.

I suspect I will have to do a replacement in subcircuits...

TEMP = V(MyTemp)

and fudge it with a voltage step :-]

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On 05/05/2014 02:49 PM, Jim Thompson wrote:
Temperature Step in a .TRAN Simulation?

Any clever soul out there figured out a way to do that?

...Jim Thompson


Easy in LTspice.

..step temp -55 125 10

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

On Mon, 05 May 2014 13:06:33 -0700, Jim Thompson wrote:

On Mon, 05 May 2014 13:58:50 -0500, Tim Wescott
wrote:

On Mon, 05 May 2014 11:49:22 -0700, Jim Thompson wrote:

Temperature Step in a .TRAN Simulation?

Any clever soul out there figured out a way to do that?

...Jim Thompson

LTSpice or regular?

I'm pretty sure you can do it with a .STEP or a .TEMP command in
LTSpice.

.STEP isn't the same as a step in temperature _during_ the simulation
run.

.STEP simply applies a data change at the _beginning_ of a run.

I want, during a transient solution, to have a temperature change to
test a temperature-related shutdown mechanism.

I suspect I will have to do a replacement in subcircuits...

TEMP = V(MyTemp)

and fudge it with a voltage step :-]

Ooh ouch. So ideally you'd like to make sure that your temperature
detection/shut down works correctly as temperature is changing
dynamically?

I think I'd separate the circuit into part A and part B, where part A is
the temperature sensor and part B is the rest. Characterize part A over
temperature, fake its behavior in a subcircuit, then make sure that part
B responds correctly to the changes in part A at a variety of different
temperatures.

It'll probably be valid, unless the temperature shows strong gradients
across the chip or changes as rapidly enough to be close to the time
constants of any RC pairs.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

On Tue, 06 May 2014 10:48:39 -0500, Tim Wescott
wrote:

On Mon, 05 May 2014 13:06:33 -0700, Jim Thompson wrote:

On Mon, 05 May 2014 13:58:50 -0500, Tim Wescott
wrote:

On Mon, 05 May 2014 11:49:22 -0700, Jim Thompson wrote:

Temperature Step in a .TRAN Simulation?

Any clever soul out there figured out a way to do that?

...Jim Thompson

LTSpice or regular?

I'm pretty sure you can do it with a .STEP or a .TEMP command in
LTSpice.

.STEP isn't the same as a step in temperature _during_ the simulation
run.

.STEP simply applies a data change at the _beginning_ of a run.

I want, during a transient solution, to have a temperature change to
test a temperature-related shutdown mechanism.

I suspect I will have to do a replacement in subcircuits...

TEMP = V(MyTemp)

and fudge it with a voltage step :-]

Ooh ouch. So ideally you'd like to make sure that your temperature
detection/shut down works correctly as temperature is changing
dynamically?

Yes. How I ended up fudging is sort of round-about, but it works...

In the actual circuit there is the equivalent of an LM94022
temperature sensor with GS0 and GS1 both set to 1's.

Internally to the overall circuit the output voltage of the LM94022
drives a comparator (with hysteresis) to effect the thermal shutdown.

Fortunately this voltage also comes out on a pin, so that the user can
monitor temperature, if he wants (to me, not very useful :-)

Since I modeled the LM94022 for this application in the first place, I
realized that the LM94022 has a weenie output, limited to +/-150uA.

So I made a test tool, an equivalent to an LM94022, but with a voltage
source output, replaced every instance of "TEMP" in the equations with
"V(MyTemp)", where "MyTemp" is an input pin.

The output of this test tool overdrives the internal LM94022 output,
if I apply a voltage to pin "MyTemp" equal to the desired temperature.

So I can apply a ramp to "MyTemp" and watch the thermal shutdown
function under transient conditions.

Works great!


I think I'd separate the circuit into part A and part B, where part A is
the temperature sensor and part B is the rest. Characterize part A over
temperature, fake its behavior in a subcircuit, then make sure that part
B responds correctly to the changes in part A at a variety of different
temperatures.

It'll probably be valid, unless the temperature shows strong gradients
across the chip or changes as rapidly enough to be close to the time
constants of any RC pairs.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

Gosh you're making it seem like rocket science.