Systems, methods, and apparatus managing access to a power management device are disclosed. A system has a primary integrated circuit and a power management integrated circuit. The primary integrated circuit has a communication controller configured to control access to a first serial bus for a plurality of subsystems in the primary integrated circuit. The power management integrated circuit is coupled to the first serial bus and to a second serial bus. An access control circuit in the power management integrated circuit is configured by the primary integrated circuit to control access to the power management integrated circuit through the second serial bus. The primary integrated circuit may be configured to write an access control configuration to the power management integrated circuit. The access control configuration may define write access rights for a secondary integrated circuit coupled to the power management integrated circuit through the second serial bus.