UM10850
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User manual
Rev. 2.4 — 13 September 2016
68 of 464
NXP Semiconductors
UM10850
Chapter 4: LPC5410x System configuration (SYSCON)
Assertion of the POR or the BOD reset, once the operating voltage attains a usable level,
starts the IRC. After the IRC-start-up time (maximum of 6
s on power-up), the IRC
provides a stable clock output. The reset remains asserted until the external Reset is
released, the oscillator is running, and the flash controller has completed its initialization.
On the assertion of any reset source (ARM software reset, POR, BOD reset, External
reset, and Watchdog reset), the following processes are initiated:
1. The IRC is enabled or starts up if not running.
2. The flash wake-up timer starts. This takes approximately 250 ms or less.
3. The boot code in the ROM starts. The boot code performs the boot tasks and may
jump to the flash.
When the internal Reset is removed, the processor begins executing at address 0, which
is initially the Reset vector mapped from the boot block. At that point, all of the processor
and peripheral registers have been initialized to predetermined values.
4.6.2 Start-up behavior
See
for the start-up timing after reset. The IRC is the default clock at Reset and
provides a clean system clock shortly after the supply pins reach operating voltage.
Fig 4.
Start-up timing
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