UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
130 of 1269
NXP Semiconductors
UM10503
Chapter 11: LPC43xx Clock Generation Unit (CGU)
the fractional part of the PLLFRACT_CTRL register (PLLFRACT[14:0]). Consecutive M
and M+1 values are then further encoded into appropriate MENC values before being
presented as input to the M-divider.
11.7.6 PLL1
11.7.6.1 Features
•
1 MHz to 50 MHz input frequency. The input from an external crystal is limited to
25 MHz.
•
9.75 MHz to 320 MHz selectable output frequency with 50% duty cycle.
•
156 MHz to 320 MHz Current Controlled Oscillator (CCO) frequency.
•
Power-down mode.
•
Lock detector.
Fig 28. PLL0 with fractional divider
Bypass
CTRL[1]
FOUT
CLKIN
32kHz
IRC
ENET_RX_CLK
ENET_TX_CLK
GP_CLKIN
CRYSTAL
PLL1
IDIVA
IDIVB
IDIVC
IDIVD
IDIVE
CTRL[27:24]
“1”
N-DIVIDER
NP_DIV[21:12]
Direct Input
CTRL[2]
PFD
Filter
CCO
Q
D
CLKEN
CTRL[4]
/2
NP_DIV[6:0]
P-DIVIDER
/2
M-DIVIDER
Direct Output
CTRL[3]
Bandwidth Select P,I,R
MDIV[31:17]
SEL_EXT
DECODER
ΣΔ MODULATOR
MDIV[16:0]
FRAC[21:0]
CTRL[12] (PLLFRACT_REQ)
PLL0AUDIO
FRACTIONAL DIVIDER
PLL0AUDIO