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#1 Jul 17, 2021
fischerjd
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Last seen: 2 weeks 4 days ago
Joined: 2021-07-17 02:31

Smoke Analysis derating formulas

Background:  I'm using the Smoke Analysis tool with its "Standard Derating" option enabled—i.e., AMS Advanced Analysis [Smoke] > ANALYSIS menu > Smoke > Derating > Standard Derating.

Question:  I'd like to know how the Smoke Analysis tool calculates the values under the "% Derating" column in Fig. 1—i.e., what formulas does the Smoke Analysis tool use to calculate the values in the "% Derating" column.

In this particular example, the Smoke Analysis tool derates resistor R1's PDM parameter to 0%, and I'd like to understand how the Smoke Analysis tool arrives at (calculates) the value 0%.

Miscellaneous:  Table 1 shows the applicable values for resistor R1.  The circuit under test is shown in Fig. 2.  The transient analysis simulation runs for 10 ms.

The PSpice Advanced Analysis User Guide does not, as far as I can tell, provide the formulas the Smoke Analysis tool uses to calculate the values under the "% Derating" column when the tool's "Standard Derating" option is enabled.

figure01.png

Figure 1. Smoke Analysis results for resistor R1.

 

Table 1. Resistor R1's relevent properties.

PARAMETER VALUE
Resistor Value 5.6 kΩ
RTMAX 200 W
RMAX 0.25 W
RSMAX 0.0125 W/°C
RVMAX 100 V
I(R1) 5.178 mADC
V(R1) 29 VDC
T_amb 27 °C

 

figure02.png

Figure 3. The circuit under test.

 

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