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LPC2917_19_1
© NXP B.V. 2007. All rights reserved.
Preliminary data sheet
Rev. 1.01 — 15 November 2007
41 of 68
NXP Semiconductors
LPC2917/19
ARM9 microcontroller with CAN and LIN
8.8.3 PCR subsystem clock description
The PCRSS is clocked by a number of different clocks. CLK_SYS_PCRSS clocks the
AHB side of the AHB to DTL bus bridge and CLK_PCR_SLOW clocks the CGU, RGU and
PMU internal logic, see
Section 7.2.2
. CLK_SYS_PCRSS is derived from
BASE_SYS_CLK, which can be switched off in low-power modes. CLK_PCR_SLOW is
derived from BASE_PCR_CLK and is always on in order to be able to wake up from
low-power modes.
8.8.4 Clock Generation Unit (CGU)
8.8.4.1
Overview
The key features are:
Fig 11. PCRSS block diagram
Power, Clock & Reset
RGU
CGU
RGU
registers
Input Deglitch/
Sync
POR
Reset Output
Delay Logic
branch
clocks
FDIV[6:0]
PLL
out0
out1
…
out9
Low Power
Ring Oscillator
(Ringo)
base
clocks
PMU
Cl
o
c
k
Ga
te
s
wakeup_a
AHB Master
Disable Grant
AHB Master
Disable Req
WARM_RST
COLD_RST
PCR_RST
RGU_RST
POR_RST
PM
U
_
re
g
C
lo
ck E
n
a
b
le
Co
n
tr
o
l
RSTN (device pin)
Reset from Watchdog counter
AHB_RST
...
...
SCU_RST
AHB2DTL
Bridge
CGU
registers
Xtal Oscillator
x
o
50
m
_ou
t
xo
5
0
m
_
in