One LTC2928 (among three) is used in the Agilent DSO9404A to monitor four negative voltages. Schematic is not available.
The question is not "how would this be possible?" but "how did they manage this LTC2928 to monitor four negative voltages?" As this IC is 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.