
19 of 59
May 25, 2004
IDT 79RC32438
System Clock Parameters
Values based on systems running at recommended supply voltages and operating temperatures, as shown in Tables
15 and
16.Figure 3 Clock Parameters Waveform
Parameter
Symbol
Reference
Edge
200MHz
233MHz
266MHz
300MHz
Units
Timing
Diagram
Reference
Min
Max
Min
Max
Min
Max
Min
Max
PCLK1
1. The CPU pipeline clock (PCLK) speed is selected during cold reset by the boot configuration vector (see Table 3). Frequency
none
200
233
200
266
200
300
MHz
Tper
5.0
4.2
5.0
3.8
5.0
3.3
5.0
ns
ICLK2,3,4
2. ICLK is the internal IPBus clock. It is always equal to PCLK divided by 2. This clock cannot be sampled externally.
3. The ethernet clock (MIIxRXCLK and MIIxTXCLK) frequency must be equal to or less than 1/2 ICLK (MIIxRXCLK and MIIxTXCLK <= 1/2(ICLK)).
4. PCICLK must be equal to or less than two times ICLK (PCICLK <= 2(ICLK)) with a maximum PCICLK of 66MHz.
Frequency
none
100
116.5
100
133
100
150
MHz
Tper
10.0
8.5
10.0
7.5
6.7
10.0
ns
CLK5
5. The input clock (CLK) is input from the external oscillator to the internal PLL.
Frequency
none
25
66.6
25
77.6
25
88.6
25
100
MHz
Tper_5a
15.0
40.0
12.9
40.0
11.2
40.0
10
40
ns
Thigh_5a,
Tlow_5a
40
60
40
60
40
60
40
60
% of
Tper_5a
Trise_5a,
Tfall_5a
—3.0
ns
Tjitter_5a
—
0.1
—
0.1
—
0.1
—
0.1
ns
Table 5 Clock Parameters
Tlow_5a
Thigh_5a
Tper_5a
CLK
Trise_5a
Tfall_5a
Tjitter_5a