The UCD9090A has 21 GPIO pins that can function as either inputs or outputs. Each GPIO has configurable output mode options including open-drain or push-pull outputs that can be actively driven to 3.3 V or ground. There are an additional two pins that can be used as either inputs or PWM outputs but not as GPOs. Table 7-4 lists possible uses for the GPIO pins and the maximum number of each type for each use. GPIO pins can be dependents in sequencing and alarm processing. They can also be used for system-level functions such as external interrupts, power-goods, resets, or for the cascading of multiple devices. GPOs can be sequenced up or down by configuring a rail without a MON pin but with a GPIO set as an enable.