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CSD17575Q3: SOA Performance Comparison with CSD17581Q3A

Paul Kim
Intellectual 1430 points
Part Number: CSD17575Q3
Other Parts Discussed in Thread: CSD17581Q3A,

hi team

CSD17575Q3 has more smaller Rdson compared to CSD17581Q3A.

so, I think CSD17575Q3 has better overall performance than CSD17581Q3A.

however, I found interest thing at SOA Curve.

I expected that CSD17575Q3 would be more better SOA curve than CSD17581Q3A over the entire Vds range,

but in fact, CSD17581Q3A has more good performance especially for 100 usec and 10 usec lines above Vds = 20V ~ 30V range.

[Q1] CSD17581Q3A has poor Rdson than CSD17575Q3,

        but may I know why CSD17581Q3A showes better SOA at 100 usec and 10 usec lines above Vds = 20V ~ 30V range ?

[Q2] I think SOA curve is at Tc = 25 degree.

        do you think CSD17581Q3A will still has better SOA curve even at Tc = 80 degree than CSD17575Q3 ?

  • 0
    TI__Mastermind 18200 points

    Paul, 

    Your observations and instincts are correct. Both of these parts are of the same silicon generation, which means the lower resistance, the bigger the die, and in theory the better the SOA. 

    The truth is, over the last few years our methods for rating and derating the SOA have improved substantially. A few things:

    1) At the time the SOA for the CSD17575Q3 was measured, we did not have the capability to measure 100us so that line and the 10us line were extrapolated based on the most conservative scenario we could imagine. For the CSD17581Q3A we were able to measure 100us data, and as you can see, there is actually a very big gap between 1ms and 100us. I would suspect if we remeasured the CSD17575Q3 we would see a similar gap.

    2) Over time, we have gotten better at building in kinks to the curves such that we can follow the measured data a little better. We also let each pulse duration have its own slope to reflect what the data indicates (note the shorter the pulse duration, generally the steeper the slope). So basically what that means is while still maintaining plenty of derating from the measured data, we can provide more aggressive SOA curves today than we could 2-3 years ago. 

    Having said that, I would expect the real CSD17575Q3 SOA to be better than that of the CSD17581Q3A, but to know how much, we would need to go back and re characterize the CSD17575Q3.