A.1.3 Power control Q-Channel signals

The subsystem provides power the following control Q-Channel interfaces to allow expansion logic to control the readiness of external expansion logic to power up and down.

  • PD_SYS Power Q-Channel interface for the PD_SYS power domain which includes the following signals:

    • SYSPWRQREQn output,

    • SYSPWRQACCEPTn input,
    • SYSPWRQDENY input,
    • SYSPWRQACTIVE input.

    These signals must be driven by logic within the PD_SYS power domain and are used to determine if it is safe to change to a lower PD_SYS power state. The interface can also be driven from a power domain more ON than the PD_SYS domain to request PD_SYS to power up. This interface is synchronous to SYSSYSUGCLK and SYSSYSCLK, except for the SYSPWRQACTIVE signal which is asynchronous.

    If you use the SYSPWRQACTIVE signal to request PD_SYS to power up, you must drive the SYSPWRQACTIVE signal HIGH at least until the PD_SYS power domain ON indication, PDSYSON, goes HIGH. This ensures that the PD_SYS is turned on correctly.

  • PD_DEBUG Power Q-Channel interface for the PD_DEBUG power domain which includes the following signals:

    • DEBUGPWRQREQn output,

    • DEBUGPWRQACCEPTn input,
    • DEBUGPWRQDENY input,
    • DEBUGPWRQACTIVE input.

    These signals must be driven by expansion logic that resides within the PD_DEBUG power domain. They are used to determine if it is safe to change to a lower PD_DEBUG power state. It can also be driven from a different power domain to wake the PD_DEBUG domain. This is synchronous to DEBUGSYSCLK, except for the DEBUGPWRQACTIVE signal which is asynchronous.

    If you use the DEBUGPWRQACTIVE signal to request PD_DEBUG to power up, you must drive the DEBUGPWRQACTIVE signal HIGH at least until the PD_DEBUG power domain ON indication, PDDEBUGON, goes HIGH. This ensures that the PD_DEBUG is turned on correctly.

  • PD_CRYPTO Power Q-Channel interface for the PD_CRYPTO power domain which includes:

    • CRYPTOPWRQREQn output,

    • CRYPTOPWRQACCEPTn input,
    • CRYPTOPWRQDENY input,
    • CRYPTOPWRQACTIVE input.

    If the CryptoCell-312 does not exist, this Q-Channel interface is handled internally according to the following recommendation about unused interfaces.

    These signals must be driven by expansion logic that resides within the PD_CRYPTO power domain which includes logic in the CryptoCell Non-Volatile Memory Interface. The signals determine if it is safe to change to a lower PD_CRYPTO power state. PD_CRYPTO only supports static power control, so this interface cannot be used to request the PD_CRYPTO power domain to power up. This interface is synchronous to CRYPTOSYSCLK, except for the CRYPTOPWRQACTIVE signal which is asynchronous.

If an interface is not used, then the QACTIVE and QDENY signals must be tied LOW and the QREQn output looped back into its QACCEPTn input.

Note:

When using the PD_SYS Power Q-Channel interface to wake the system from hibernation, you must consider context restoration.
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