Datasheet
LPC185X_3X_2X_1X All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet Rev. 4.1 — 6 May 2014 82 of 148
NXP Semiconductors
LPC185x/3x/2x/1x
32-bit ARM Cortex-M3 microcontroller
output frequency. The output frequency can be set as a multiple of the sampling frequency
f
s
to 32f
s
, 64f
s
, 128 f
s
, 256 f
s
, 384 f
s
, 512 f
s
and the sampling frequency f
s
can
range from 16 kHz to 192 kHz (16, 22.05, 32, 44.1, 48, 96,192) kHz. Many other
frequencies are possible as well using the integrated fractional divider.
7.20.7 System PLL1
The PLL1 accepts an input clock frequency from an external oscillator in the range of
10 MHz to 25 MHz. The input frequency is multiplied up to a high frequency with a Current
Controlled Oscillator (CCO). The multiplier can be an integer value from 1 to 32. The CCO
operates in the range of 156 MHz to 320 MHz. This range is possible through an
additional divider in the loop to keep the CCO within its frequency range while the PLL is
providing the desired output frequency. The output divider can be set to divide by 2, 4, 8,
or 16 to produce the output clock. Since the minimum output divider value is 2, it is
insured that the PLL output has a 50 % duty cycle. The PLL is turned off and bypassed
following a chip reset. After reset, software can enable the PLL. The program must
configure and activate the PLL, wait for the PLL to lock, and then connect to the PLL as a
clock source. The PLL settling time is 100 s.
7.20.8 Reset Generation Unit (RGU)
The RGU allows generation of independent reset signals for individual blocks and
peripherals.
7.20.9 Power control
The LPC185x/3x/2x/1x feature several independent power domains to control power to
the core and the peripherals (see Figure 9
). The RTC and its associated peripherals (the
alarm timer, the CREG block, the OTP controller, the back-up registers, and the event
router) are located in the RTC power-domain. The main regulator or a battery supply can
power the RTC. A power selector switch ensures that the RTC block is always powered
on.