© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
User manual
Rev. 01 — 15 August 2005
34
Philips Semiconductors
UM10139
Volume 1
Chapter 3: System Control Block
3.8.11 PLL0 and PLL1 configuring examples
Example 1: an application not using the USB - configuring the PLL0
System design asks for F
OSC
= 10 MHz and requires CCLK = 60 MHz.
Based on these specifications, M = CCLK / Fosc = 60 MHz / 10 MHz = 6. Consequently,
M - 1 = 5 will be written as PLLCFG[4:0].
Value for P can be derived from P = F
CCO
/ (CCLK x 2), using condition that F
CCO
must be
in range of 156 MHz to 320 MHz. Assuming the lowest allowed frequency for
F
CCO
= 156 MHz, P = 156 MHz / (2 x 60 MHz) = 1.3. The highest F
CCO
frequency criteria
produces P = 2.67. The only solution for P that satisfies both of these requirements and is
listed in
is P = 2. Therefore, PLLCFG[6:5] = 1 will be used.
Example 2: an application using the USB - configuring the PLL1
System design asks for F
OSC
= 12 MHz and requires the USB clock of 48 MHz.
Based on these specifications, M = 48 MHz / Fosc = 48 MHz / 12 MHz = 4. Consequently,
M - 1 = 3 will be written as PLLCFG[4:0].
Value for P can be derived from P = F
CCO
/ (48 MHz x 2), using condition that F
CCO
must
be in range of 156 MHz to 320 MHz. Assuming the lowest allowed frequency for
F
CCO
= 156 MHz, P = 156 MHz / (2 x 48 MHz) = 1.625. The highest F
CCO
frequency
criteria produces P = 3.33. Solution for P that satisfy both of these requirements and are
listed in
are P = 2 and P = 3. Therefore, either of these two values can be used to
program PLLCFG[6:5] in the PLL1.
Example 2 has illustrated the way PLL1 should be configured. Since PLL0 and PLL1 are
independent, the PLL0 can be configured using the approach described in Example 1.
Table 22:
PLL Divider values
PSEL Bits (PLLCFG bits [6:5])
Value of P
00
1
01
2
10
4
11
8
Table 23:
PLL Multiplier values
MSEL Bits (PLLCFG bits [4:0])
Value of M
00000
1
00001
2
00010
3
00011
4
...
...
11110
31
11111
32