Power Management
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15.3.5 Power-Saving Capability
The OMAP5910 device has several power-saving modes that help to reduce
the operating current by stopping the clock signals of the unused (inactive)
domain(s). The idle controls to the DSP, the MPU, and the traffic controller
provide a flexible and an efficient power-saving mechanism. The following list
of power-saving modes is given as an example only, because other modes are
possible. The system software can program the OMAP5910 device to operate
in any of these modes for a specific application.
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Mode 0: The DSP is partially in the idle mode (see DSP idle protocol).
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Mode 1: The DSP is in the global idle mode.
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Mode 2: The MPU is in the idle mode (DSP is still running) for both:
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System DMA controller is active.
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System DMA controller is not active.
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Mode 3: Both MPU and DSP are set in the idle mode (peripherals are still
active) for both:
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System DMA controller is active.
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System DMA controller is not active.
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Mode 4: The MPU, the DSP, and traffic controller are stopped (the traffic
controller can be stopped only if both the MPU and the DSP are in idle) for
both:
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Peripheral modules are individually stopped.
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All peripherals are stopped.
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Mode 5: The MPU, the DSP, peripherals, and DPLL (1) are stopped; how-
ever, the timer/watchdog (or OS-timer) is still active.
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Mode 6 (chip idle): The MPU, the DSP, peripherals, DPLL (1), and timers
are stopped, while the ULPD clock source remains the only active clock
signal.
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Mode 7 (deep sleep): All internal system clocks (the MPU, the DSP,
peripherals, DPLL (1) and timers) and the ULPD reference clock source
are stopped, leaving the OMAP5910 device in a static state in which it
consumes the lowest possible power.
In all power-saving modes, the OMAP5910 device retains all RAM data (keeps
the memory data), and the register configuration values (for example, the
frequency selection is maintained, etc.). The data to output terminals is also
maintained, and input terminals are set to logic low or logic high (not floating)
to reduce the current from flowing through the input logic.