There are essentially 3 general configurations of Galvanic isolator2
These are conventionally shown as 'positive' voltage but, unlike zener barriers, they are isolated so the concept of positive and negative barriers becomes irrelevant.
Due to their complexity they have to be designed specifically for the application circuit or signal type
The basic output circuit of isolation interfaces tends to be similar to that used in zener barriers but, particularly for custom applications, output circuits can be complex and use other techniques and components for power limitation ↩
Shown here with a 'representative' zener diode and resistor output which is not necessarily the actual circuit used which will vary between isolator types. ↩