ISO1540是这样的，这点在datasheet中有描述： 大概在0.4V这里有个offset。Isolated bidirectional communication is accomplished within these devices by offsetting the low-level output voltage on side 1 to a value greater than the highlevel input voltage on side 1, thus preventing an internal logic latch that otherwise would occur with standard digital isolators.
或者如果您不需要双向隔离的话，可以考虑ISO1541 ，这个和ISO1540的区别在于clock是单向的，只有data是双向的。
