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30140-23 参数 Datasheet PDF下载

30140-23图片预览
型号: 30140-23
PDF下载: 下载PDF文件 查看货源
内容描述: 的Geode ™ GXM处理器与MMX支持集成的x86解决方案 [Geode⑩ GXm Processor Integrated x86 Solution with MMX Support]
分类和应用: 微控制器和处理器外围集成电路微处理器
文件页数/大小: 244 页 / 4221 K
品牌: NSC [ National Semiconductor ]
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Power Management (Continued)  
selected by setting bit 0 in the PM Clock Stop Control  
Register. If you are using DRAMs without self refresh, you  
must supply a 32 kHz clock to the CLK32KHZ bit to keep  
the refresh circuitry active when using the lower-power  
Suspend mode.  
power mode turns off all internal clocks generated from  
SYSCLK. This mode is selected by setting bit 0 in the PM  
Clock Stop Control Register. If the bit is set and DRAMS  
without self-refresh are used, a 32 KHz clock must be  
supplied to the CLK32KHZ input to keep the refresh circuit  
active.  
While also in 3-Volt Suspend Mode, the CS5530 contin-  
ues to decrement all of its device timers, and it responds  
to external SMI interrupts using the 32 kHz clock input  
(CLK32KHz) pin. Any SMI event, timer or pin, causes the  
CS5530 to deassert the SUSP_3V pin, starting the sys-  
tem clocks. The CS5530 holds SUSP# active for a pre-  
programmed period that varies from 0 to 16 ms, which  
allows the clocks to settle. After this period expires, the  
CS5530 deasserts SUSP#. SMI# is held active for the  
entire period, so that the GXm processor status registers  
are updated.  
The GXm processor enters the Suspend mode in  
response to SUSP# input assertion only when certain  
conditions are met. First, the USE_SUSP bit must be set  
in CCR2 (Index C2h[7]). In addition, execution of the cur-  
rent instructions and any pending decoded instructions  
and associated bus cycles must be completed. SUSP# is  
sampled on the rising edge of SYSCLK, and must meet  
specified setup and hold times to be recognized at a par-  
ticular SYSCLK edge.  
When all conditions are met, the SUSPA# output is  
asserted. The time from assertion of SUSP# to the activa-  
tion of SUSPA# depends on which instructions were  
decoded prior to assertion of SUSP#. Normally, once  
SUSP# has been sampled inactive the SUSPA# output  
will be deactivated within two clocks. However, the deacti-  
vation of SUSPA# may be delayed until the end of an  
active refresh cycle.  
The SUSP_3V pin can be active either high or low. The  
pin is an input during POR, and is sampled to determine  
its inactive state. This allows a designer to match the  
active state of SUSP_3V to the inactive state for a clock  
driver output enable with a pull-up or pull-down resistor.  
6.5 SUSPEND MODE AND BUS CYCLES  
The following subsections describe the bus cycles when  
the Suspend mode is implemented.  
If the CPU is already in a Suspend mode initiated by  
SUSP#, one occurrence of NMI, INTR and SMI# is stored  
for execution after Suspend mode is exited. The CPU also  
allows PCI accesses during a SUSP#-initiated Suspend  
mode (see Figure 6-1). If the CPU is in the middle of a  
PCI access when SUSP# is asserted, the assertion of  
SUSPA# will be delayed until the PCI access is com-  
pleted.  
6.5.1 Initiating Suspend with SUSP#  
The GXm processor has two low-power Suspend modes.  
The mode is selected by bit 0 in the PM Clock Stop Con-  
trol Register. One mode (bit 0 cleared) turns off the inter-  
nal clocks to everything but the internal Display and  
Memory Controllers, keeping the display active. A lower-  
SYSCLK  
SUSP#  
SUSPA#  
Figure 6-1. SUSP#-Initiated Suspend Mode  
Revision 3.1  
175  
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