Electronics > Power & Renewable Energy

Current Sensing MOSFET's


Hello everyone!
I came across this application note:
talking about Current Sensing MOSFET's. Essentially they are two in one FET's, with one of them much smaller than the other, providing a fixed small percentage of the total current in a sense pin (something in the order of 1:1000th). This means one only has to measure this small current and multiply it by a factor in order to measure the total FET's current, with far fewer losses than the usual inline shunt approach.
However, after researching many of the more famous manufacturers i came up short, only finding the IXYS MMIX1T132N50P3
 (Application note here: https://www.ixys.com/Documents/Appnotes/High_Current_Power_MOSFET_with_Current_Mirror_and_Temperature_Sense_Diodes.pdf),
which is a high voltage, relatively low current device, while I need higher current capability at about 50V, and the HEXSense series from International Rectifier, which seems to be long obsolete.
To make matters worse, there doesn't seem to be a parametric search that sifts these types of MOSFET, so I wondered if anyone here would know any more of these devices, or to tell me why they are a bad idea.
Best regards, Tiago

David Hess:
I did a search for them last week and came to the same conclusions; their availability is poor and trying to select for them is useless.  I limited my search to 4 pin packages and even that was not enough to find them.

After contacting ON Semiconductor I was told they no longer sell any SenseFET, so I guess it's end of the line for it.


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