LTC2928: what is the trick to allow *four negative* voltage monitoring?

[F1GWR]

Hi,

I saw an example of one LTC2928 (among three) used in the Agilent DSO9404A to monitor four negative voltages. Schematic is not available.

The question is not "would this be possible?", because it is, but "which application circuit using this LTC2928 would be able to monitor four negative voltages?" As this IC was initially designed solely for four positive or one negative and three positive depending on the VSEL tying.

Checked datasheet, app notes and design notes but didn't find any clue...

Any help appreciated.

[Andree Henkel]

look to the left: OP484, likely 3 of the four channels of it do it.