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UM10850
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© NXP B.V. 2016. All rights reserved.
User manual
Rev. 2.4 — 13 September 2016
48 of 464
NXP Semiconductors
UM10850
Chapter 4: LPC5410x System configuration (SYSCON)
4.5.37 PLL registers
The PLL provides a wide range of frequencies and can potentially be used for many
on-chip functions. the PLL can be used with or without a spread spectrum clock generator.
See
Section 4.6.4 “PLL functional description”
for additional details of PLL operation.
4.5.37.1 System PLL control register
The SYSPLLCTRL register provides most of the control over basic selections of PLL
modes and operating details.
Table 66.
System PLL control register (SYSPLLCTRL, address 0x4000 01B0 bit description
Bit
Symbol
Value
Description
Reset
value
3:0
SELR
Bandwidth select R value
9:4
SELI
Bandwidth select I value
14:10
SELP
Bandwidth select P value
15
BYPASS
PLL bypass control
1
0
Disabled. PLL CCO is used to create the PLL output.
1
Enabled. PLL is bypassed, the PLL input clock is routed directly to the PLL output
(default).
16
BYPASS
CCODIV2
Bypass feedback clock divide by 2.
0
0
Divide by 2. The CCO feedback clock is divided by 2 in addition to the programmed
M divide.
1
Bypass. The CCO feedback clock is divided only by the programmed M divide.
17
UPLIMOFF
Disable upper frequency limiter.
For spread spectrum mode: SEL_EXT = 0, BANDSEL = 0, and UPLIMOFF = 1.
0
0
Normal mode.
1
Upper frequency limiter disabled.
18
BANDSEL
PLL filter control. Set this bit to one when the spread spectrum controller is disabled
or at low frequencies.
For spread spectrum mode: SEL_EXT = 0, BANDSEL = 0, and UPLIMOFF = 1.
0
0
SSCG control. The PLL filter uses the parameters derived from the spread spectrum
controller.
1
MDEC control. The PLL filter uses the programmable fields SELP, SELR, and SELI
in this register to control the filter constants.
19
DIRECTI
PLL0 direct input enable
0
0
Disabled. The PLL input divider (N divider) output is used to drive the PLL CCO.
1
Enabled. The PLL input divider (N divider) is bypassed. the PLL input clock is used
directly to drive the PLL CCO.
20
DIRECTO
PLL0 direct output enable
0
0
Disabled. The PLL output divider (P divider) is used to create the PLL output.
1
Enabled. The PLL output divider (P divider) is bypassed, the PLL CCO output is
used as the PLL output.
31:21
-
Reserved. Read value is undefined, only zero should be written.
-