UM10346_1
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 01 — 2 November 2009
54 of 132
NXP Semiconductors
UM10346
LPC980/982 User manual
Table 41.
Real-time Clock/System Timer clock sources
FOSC2:0
RCCLK
RTCS1:0
RTC clock source
CPU clock source
000
0
00
High frequency crystal
High frequency crystal
/DIVM
01
10
11
High frequency crystal
/DIVM
1
00
High frequency crystal
Internal RC oscillator
01
10
11
Internal RC oscillator
001
0
00
Medium frequency crystal
Medium frequency crystal
/DIVM
01
10
11
Medium frequency crystal
/DIVM
1
00
Medium frequency crystal
Internal RC oscillator
01
10
11
Internal RC oscillator
010
0
00
Low frequency crystal
Low frequency crystal
/DIVM
01
10
11
Low frequency crystal
/DIV
1
00
Low frequency crystal
Internal RC oscillator
01
10
11
Internal RC oscillator
011
0
00
High frequency crystal
Internal RC oscillator
/DIVM
01
Medium frequency crystal
10
Low frequency crystal
11
Internal RC oscillator
/DIVM
1
00
High frequency crystal
Internal RC oscillator
01
Medium frequency crystal
10
Low frequency crystal
11
Internal RC oscillator