Dell has two dongle sizes: 7.4mm and 4.5mm. Looking at photos of the Inspiron 5570, it definitely uses the 4.5mm size. The older 7.4mm connector is found pretty much only on some Latitude, Precision, and Alienware systems these days. For the first two, it's primarily to maintain compatibility with older AC adapters since businesses may have a lot of them in inventory and/or deployed at desks and such. For Alienware systems, Dell doesn't seem to make AC adapters that offer more than 130W with the new connector style, and at least most Alienware systems require more than that.
ejn63
10 Elder
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30.7K Posts
0
August 14th, 2018 18:00
Just about all the newer systems use the 4 mm plug.
jphughan
9 Legend
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14K Posts
1
August 14th, 2018 20:00
Dell has two dongle sizes: 7.4mm and 4.5mm. Looking at photos of the Inspiron 5570, it definitely uses the 4.5mm size. The older 7.4mm connector is found pretty much only on some Latitude, Precision, and Alienware systems these days. For the first two, it's primarily to maintain compatibility with older AC adapters since businesses may have a lot of them in inventory and/or deployed at desks and such. For Alienware systems, Dell doesn't seem to make AC adapters that offer more than 130W with the new connector style, and at least most Alienware systems require more than that.