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Projects, Designs, and Technical Stuff / Re: Transistors - die pictures
« Last post by RoGeorge on Today at 07:59:13 pm »When they give 4m\$\Omega\$ and 202A, that made me curious. I've doubted that the outside terminals can withstand at 200A without melting, or at least going red hot, let alone the bonding wires.
The fine print in the datasheet https://www.infineon.com/dgdl/irf1404pbf.pdf?fileId=5546d462533600a4015355dae92618b0 says that the 202A continuous current would be supported, just that those 202A are a calculated value, based on the thermal resistance and the max allowed junction temperature. The package limit is 75A, so the 202A continuous drain current is a lie. Quote from the datasheet, remark 6 regarding max Id:
The 4m\$\Omega\$ also seemed too small, and it has a fine print, too, remark 4 in the datasheet:
But why is the Rds value specified at such high Id. Why didn't they measure it at a 10 times lower or so current, and no pulses? Is it something in the MOSFET physics, that makes it achieve very low Rds only at huge drain current, so they went took the extra effort measuring pulses, only to obtain a much lower Rds value for the datasheet (similar with the 202A continuous but no more than 75A)?
Why did they bother using huge current and pulses to measure Rds on?
The fine print in the datasheet https://www.infineon.com/dgdl/irf1404pbf.pdf?fileId=5546d462533600a4015355dae92618b0 says that the 202A continuous current would be supported, just that those 202A are a calculated value, based on the thermal resistance and the max allowed junction temperature. The package limit is 75A, so the 202A continuous drain current is a lie. Quote from the datasheet, remark 6 regarding max Id:
Quote
Calculated continuous current based on maximum allowable
junction temperature. Package limitation current is 75A.
The 4m\$\Omega\$ also seemed too small, and it has a fine print, too, remark 4 in the datasheet:
Quote
Pulse width ≤ 400μs; duty cycle ≤ 2%.That is because the value is specified at Vgs = 10V and Id = 121A, which Id is higher than the max 75A continuous supported by the package, thus the time and the duty factor limitations. OK, understandable.
But why is the Rds value specified at such high Id. Why didn't they measure it at a 10 times lower or so current, and no pulses? Is it something in the MOSFET physics, that makes it achieve very low Rds only at huge drain current, so they went took the extra effort measuring pulses, only to obtain a much lower Rds value for the datasheet (similar with the 202A continuous but no more than 75A)?
Why did they bother using huge current and pulses to measure Rds on?