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DPCLK3 参数 Datasheet PDF下载

DPCLK3图片预览
型号: DPCLK3
PDF下载: 下载PDF文件 查看货源
内容描述: 的Cyclone III器件手册 [Cyclone III Device Handbook]
分类和应用:
文件页数/大小: 274 页 / 7302 K
品牌: ALTERA [ ALTERA CORPORATION ]
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Chapter 5: Clock Networks and PLLs in the Cyclone III Device Family  
5–27  
PLL Reconfiguration  
Figure 5–20 shows how to adjust PLL counter settings dynamically by shifting their  
new settings into a serial shift register chain or scan chain. Serial data shifts to the scan  
chain via the scandataport, and shift registers are clocked by scanclk. The maximum  
scanclkfrequency is 100 MHz. After shifting the last bit of data, asserting the  
configupdatesignal for at least one scanclkclock cycle synchronously updates the  
PLL configuration bits with the data in the scan registers.  
Figure 5–20. PLL Reconfiguration Scan Chain  
F
VCO  
from M counter  
from N counter  
PFD  
LF/K/CP  
VCO  
scandata  
scanclkena  
configupdate  
inclk  
/C4  
/C3  
/C2  
/C1  
/C0  
/M  
/N  
scandataout  
scandone  
scanclk  
1
The counter settings are updated synchronously to the clock frequency of the  
individual counters. Therefore, not all counters update simultaneously.  
To reconfigure the PLL counters, perform the following steps:  
1. The scanclkenasignal is asserted at least one scanclkcycle prior to shifting in the  
first bit of scandata Dn).  
(
2. Serial data (scandata) is shifted into the scan chain on the second rising edge of  
scanclk  
.
3. After all 144 bits have been scanned into the scan chain, the scanclkenasignal is  
deasserted to prevent inadvertent shifting of bits in the scan chain.  
4. The configupdatesignal is asserted for one scanclkcycle to update the PLL  
counters with the contents of the scan chain.  
5. The scandonesignal goes high indicating that the PLL is being reconfigured. A  
falling edge indicates that the PLL counters have been updated with new settings.  
6. Reset the PLL using the aresetsignal if you make any changes to the M, N,  
post-scale output C counters, or the  
ICP , R, C settings.  
7. You can repeat steps 1 through 5 to reconfigure the PLL any number of times.  
July 2012 Altera Corporation  
Cyclone III Device Handbook  
Volume 1  
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