UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
113 of 1269
NXP Semiconductors
UM10503
Chapter 11: LPC43xx Clock Generation Unit (CGU)
11.6.4.5 PLL0AUDIO fractional divider register
When the fractional divider is active, the sigma-delta modulator block generates divider
values M and M+1 in the correct proportion so that an average division ratio of M+K/L is
realized where 0<=K<=L and M, K, and L are integer values. M Is determined by the
integer part of the PLLFRACT_CTRL register (PLLFRACT[21:15]) and K is determined by
the fractional part of the PLLFRACT_CTRL register (PLLFRACT[14:0]). Consecutive M
and M+1 values are then further encoded into appropriate MDEC values before being
presented as input to the M-divider.
11.6.5 PLL1 registers
The PLL1 is used for the core and all peripheral blocks.
11.6.5.1 PLL1 status register
11.6.5.2 PLL1 control register
Table 78.
PLL0AUDIO fractional divider register (PLL0AUDIO_FRAC, address 0x4005 003C)
bit description
Bit
Symbol
Description
Reset
value
Access
21:0
PLLFRACT_CTRL
PLL fractional divider control word
000 0000
R/W
31:22
-
Reserved
-
-
Table 79.
PLL1 status register (PLL1_STAT, address 0x4005 0040) bit description
Bit
Symbol
Description
Reset
value
Access
0
LOCK
PLL1 lock indicator
0
R
31:1
-
Reserved
-
-
Table 80.
PLL1_CTRL register (PLL1_CTRL, address 0x4005 0044) bit description
Bit
Symbol
Value Description
Reset
value
Access
0
PD
PLL1 power down
1
R/W
0
PLL1 enabled
1
PLL1 powered down
1
BYPASS
Input clock bypass control
1
R/W
0
CCO clock sent to post-dividers. Use for
normal operation.
1
PLL1 input clock sent to post-dividers
(default).
2
-
Reserved. Do not write one to this bit.
0
R/W
5:3
-
Reserved. Do not write one to these bits.
-
-