Device and method for selectively powering down integrated circuit blocks

摘要

Presented is a power down circuit for use in a system on Chip SOC. Within the SOC are several circuit blocks, each of them having a local clock. A system clock is coupled to the circuit blocks and is structured to act as the local clock of selected circuit blocks. A power control manager provides a signal that at least partially determines whether the system clock will act as the local clock for some of the circuit blocks. Within the circuit blocks is a local power control structured to selectively maintain the system clock as the local clock of the block after the local power control receives a signal to shut down the block from the power control manager, if the block is currently busy when the signal to shut down the block is received. Also presented is a method that can be operated using the above system. The method includes generating a system clock signal that is for use as a local clock signal for circuit blocks that have not been shutdown. A shutdown request signal is generated to selectively power down some of the circuit blocks. That shutdown request signal is transmitted to a power down circuit within the circuit block to be shutdown. The power down circuit receives the signal to power down the circuit block, as well as a current status of the block. After an evaluation, the cirucuit block is shut down if the signal to power down is received and the circuit block is presently idle.