DF8064101211300SR0VY Просмотр технического описания (PDF) - Intel

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Intel® Atom™ Processor D2000 and N2000 Series

Intel 

7.3.2

7.3.2.1

7.3.2.2

7.3.2.3

DRAM Power Management and Initialization

The processor implements extensive support for power management on the SDRAM

interface. There are four SDRAM operations associated with the Clock Enable (CKE)

signals, which the SDRAM controller supports. The processor drives four CKE pins to

perform these operations.

Initialization Role of CKE

During power-up, CKE is the only input to the SDRAM that has its level is recognized

(other than the DDR3 reset pin) once power is applied. It must be driven LOW by the

DDR controller to make sure the SDRAM components float DQ and DQS during

powerup.

CKE signals remain LOW (while any reset is active) until the BIOS writes to a

configuration register. Using this method, CKE is guaranteed to remain inactive for

much longer than the specified 200 micro-seconds after power and clocks to SDRAM

devices are stable.

Conditional Self-Refresh

Intel Rapid Memory Power Management (Intel RMPM) conditionally places memory into

self-refresh in the package C3 and C6 low-power states. RMPM functionality depends

on graphics/display state (relevant only when internal graphics is being used), as well

as memory traffic patterns generated by other connected I/O devices.

When entering the Suspend-to-RAM (STR) state, the processor core flushes pending

cycles and then enters all SDRAM ranks into self refresh. In STR, the CKE signals

remain LOW so the SDRAM devices perform self-refresh.

The target behavior is to enter self-refresh for the package C3 and C6 states as long as

there are no memory requests to service.

Dynamic Power Down Operation

Dynamic power-down of memory is employed during normal operation. Based on idle

conditions, a given memory rank may be powered down. The IMC implements

aggressive CKE control to dynamically put the DRAM devices in a power down state.The

processor core controller can be configured to put the devices in active power down

(CKE deassertion with open pages) or precharge power down (CKE deassertion with all

pages closed). Precharge power down provides greater power savings but has a bigger

performance impact, since all pages will first be closed before putting the devices in

power down mode.

If dynamic power-down is enabled, all ranks are powered up before doing a refresh

cycle and all ranks are powered down at the end of refresh.

Datasheet - Volume 1 of 2

111

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