Pulse Width Calculations
Pulse Width Low Tpwl = (divOut*Pwdth)/(CKREF*14)
To meet minimum pulse width specification, divOut*Pwdth≥Tpwl*(TCKREF*14).
Bit times based on PWS0, PWS1 (Pwdth = 7, 13, 17), divide by divOut = 0.954, 1, 2, 3.
Example: Tpwl=60ns CKREF=26MHz
CKP Pulsewidth = (2*13)/(26MHz*14)
if DivOut=2, Pwdth=13 bitTimes=26. Tpwl=71.4ns
Serializer Setup
PLL1
PLL0
0
0
0
0
0
0
0
0
0
1
0
1
0
1
0
1
1
0
1
0
1
0
1
0
1
1
1
1
1
1
1
1
Deserializer Setup
PWS1 PWS0
0
0
0
1
1
0
1
1
0
0
0
1
1
0
1
1
0
0
0
1
1
0
1
1
0
0
0
1
1
0
1
1
PLL
DivOut
0.954
0.954
0.954
0.954
1
1
1
1
2
2
2
2
3
3
3
3
Pwidth
7
7
13
17
7
7
13
17
7
7
13
17
7
7
13
17
CKP-PWL
Bit Times
6.7
6.7
12.4
16.2
7
7
13
17
14
14
26
34
21
21
39
51
CKREF Frequency
19.2MHz
26Mhz
24.8
24.8
46.1
60.3
26.0
26.0
48.4
63.2
52.1
52.1
96.7
126.5
78.1
78.1
145.1
189.7
18.3
18.3
34.1
44.6
19.2
19.2
35.7
46.7
38.5
38.5
71.4
93.4
57.7
57.7
107.1
140.1
Table 8. CKP Pulse Widths (in nanoseconds) for Standard Cell Phone Operating Frequencies(5)
Note:
5. CKP Pwidth assumes minimal slew rate at the 50% transition point.
© 2006 Fairchild Semiconductor Corporation
FIN212AC Rev. 1.0.1
7
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