The polarity can be configured to choose whether the alert signal is active-low or active-high. Switching polarity verifies compatibility with the logic and hardware design of the system. Active Low (default) is where the ALERT pin pulls low when a fault occurs. Active low is preferred for wired-OR interrupt lines and open-drain systems allowing multiple devices to signal "interrupt" without short ciruiting or damaging other devices. Active high is when the ALERT pin drives high when a fault occurs. Active high is useful when interfacing directly with logic expecting a high-true interrupt. Polarity is configurable on digital devices. Some analog switchs provide both polarity outputs like LM57.

Figure 3-1 Types of Polarity