UM10360 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
User manual Rev. 3 — 19 December 2013 65 of 841
NXP Semiconductors
UM10360
Chapter 4: LPC176x/5x Clocking and power control
Note that the DAC peripheral does not have a control bit in PCONP. To enable the DAC,
its output must be selected to appear on the related pin, P0.26, by configuring the
PINSEL1 register. See Section 8.5.2 “
Pin Function Select Register 1 (PINSEL1 -
0x4002 C004)”.
4.8.10 Power control usage notes
After every reset, the PCONP register contains the value that enables selected interfaces
and peripherals controlled by the PCONP to be enabled. Therefore, apart from proper
configuring via peripheral dedicated registers, the user’s application might have to access
the PCONP in order to start using some of the on-board peripherals.
Power saving oriented systems should have 1s in the PCONP register only in positions
that match peripherals really used in the application. All other bits, declared to be
"Reserved" or dedicated to the peripherals not used in the current application, must be
cleared to 0.
4.8.11 Power domains
The LPC176x/5x provides two independent power domains that allow the bulk of the
device to have power removed while maintaining operation of the Real Time Clock.
The VBAT pin supplies power only to the RTC domain. The RTC requires a minimum of
power to operate, which can be supplied by an external battery. Whenever the device core
power is present, that power is used to operate the RTC, causing no power drain from a
battery when main power is available.
27 PCI2S I
2
S interface power/clock control bit. 0
28 - Reserved. NA
29 PCGPDMA GPDMA function power/clock control bit. 0
30 PCENET Ethernet block power/clock control bit. 0
31 PCUSB USB interface power/clock control bit. 0
Table 46. Power Control for Peripherals register (PCONP - address 0x400F C0C4) bit
description
Bit Symbol Description Reset
value
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