UM10208_2
© NXP B.V. 2007. All rights reserved.
User manual
Rev. 02 — 1 June 2007
50 of 362
NXP Semiconductors
UM10208
Chapter 6: LPC2800 DC-DC converter
4.3 DCDC Clock Select register (DCDCCLKSEL - address 0x8000 500C)
The DC-DC converter may be operated from the Ring oscillator contained in the DC-DC
converter block or from the 12 MHz clock source from the CGU. If a clock from the CGU is
used, it must be configured and stable at the CGU output before the DC-DC converter is
asked to switch clock sources.
101
1.352
1.380
1.408
110
1.247
1.300
1.327
111
1.196
1.221
1.246
Table 30.
Adjustment range for DCDC converter 2
DCDCADJUST1 bits
Low threshold
Typical
High threshold
Table 31.
DCDC Clock Select register (DCDCCLKSEL - address 0x8000 500C)
Bit
Symbol
Description
Reset value
0
DCDCCLKSEL
This bit indicates to the DCDC converter block
whether the ring oscillator or a 12 MHz clock
source from the CGU should be used to control the
DC-DC converters.
0 - The ring oscillator is used to control the DC-DC
converters.
1 - Write this value when a 12 MHz clock has been
set up in the CGU, has stabilized, and should now
be used to control the DC-DC converters.
0
31:1
-
Reserved, user software should not write ones to
reserved bits. The value read from a reserved bit is
not defined.
-