The PBUS function is a dedicated function that supports one-out/all-out requirements in automotive exterior light systems. In a typical rear lamp design, multiple LED drivers are used to support the large number of LEDs required. In such a design, controlling multiple chips may become a problem, as would additional circuits to support fault events during the operation. To overcome these issues, BD18337/347 have a PBUS I/O pin which is used to share the fault condition event, such as LED open fault, in-between connected series drivers as shown in the figure here. Any fault event will pull down the PBUS output which will be relayed to all connected drivers to shut all channel outputs off at once. This creates a one-out/all-out function with a simple pin connection.