Posts: 2
Registered: ‎03-09-2017
Accepted Solution

Si8751 Isolation

I would like to use the Si8751 as a high side FET driver like in Figure 3.1 of the datasheet.  Table 4.8 of the datasheet says that the voltage on any pin can't be higher than VDD +0.5V with respect to ground.  Does this mean that the source pin (Pin 5) can't be more than VDD +0.5V with respect to the ground pin (Pin 4)?  That is the way I read the datasheet but it doesn't make sense if the input and output sides of the chip are supposed to be isolated.

Posts: 31
Registered: ‎11-07-2004

Re: Si8751 Isolation

You are correct that this phrasing seems illogical. It should read something like, "Voltage on any pin, 1 through 4, with respect to ground". However, even that doesn't account for the Si8752 which doesn't really have a ground pin. 

You should have no problems using the Si8751 as a high side switch as shown in the diagram.