at89c5131 ATMEL Corporation, at89c5131 Datasheet - Page 21

• Manufacturer Part Number: at89c5131
• Description: 8-bit Flash Microcontroller With Full Speed Usb Device At89c5131
• Manufacturer: ATMEL Corporation

PLL Programming
Divider Values
4136C–USB–04/05
The PLL is programmed using the flow shown in Figure 9. As soon as clock generation
is enabled user must wait until the lock indicator is set to ensure the clock output is
stable.
Figure 9. PLL Programming Flow
To generate a 48 MHz clock using the PLL, the divider values have to be configured fol-
lowing the oscillator frequency. The typical divider values are shown in Table 27.
Table 27. Typical Divider Values
Oscillator Frequency
12 MHz
16 MHz
18 MHz
20 MHz
24 MHz
32 MHz
40 MHz
3 MHz
6 MHz
8 MHz
R+1
Configure Dividers
16
12
12
Programming
8
6
4
3
8
2
3
PLL Locked?
N3:0 = xxxxb
R3:0 = xxxxb
LOCK = 1?
Enable PLL
PLLEN = 1
PLL
N+1
10
1
1
1
1
1
3
5
1
2
AT89C5131
PLLDIV
F0h
B4h
B9h
70h
50h
30h
20h
72h
10h
21h
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