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OSC5

Internal Multiple-Frequency Clock-Signal Generator

XC3000
XC4000E
XC4000X
XC5200
XC9000
Spartan
SpartanXL
Virtex
N/A
N/A
N/A
Primitive
N/A
N/A
N/A
N/A

figures/x4971n.gif

OSC5 provides internal clock signals in applications where timing is not critical. The available frequencies are determined by FPGA device components that are process dependent. Therefore, the available frequencies vary from device to device. Use only one OSC5 per design. The OSC5 is not available if the CK_DIV element is used.

The clock frequencies of the OSC1 and OSC2 outputs are determined by specifying the DIVIDE1_BY=n1 attribute for the OSC1 output and the DIVIDE2_BY=n2 attribute for the OSC2 output. n1 and n2 are integer numbers by which the internal 16-MHz clock is divided to produce the desired clock frequency. The available frequency options are shown in the table.

n1
OSC1 Frequency
n2
OSC2 Frequency
4
4 MHz
2
8 MHz
16
1 MHz
8
2 MHz
64
250 kHz
32
500 kHz
256
63 kHz
128
125 kHz


1,024
16 kHz


4,096
4 kHz


16,384
1 kHz


65,536
244 Hz

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