Datasheet

LPC81XM All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet Rev. 4.3 — 22 April 2014 58 of 76
NXP Semiconductors
LPC81xM
32-bit ARM Cortex-M0+ microcontroller
14. Application information
14.1 Typical wake-up times
[1] The wake-up time measured is the time between when a GPIO input pin is triggered to wake the device up
from the low power modes and from when a GPIO output pin is set in the interrupt service routine (ISR)
wake-up handler.
[2] IRC enabled, all peripherals off.
[3] Watchdog oscillator disabled, Brown-Out Detect (BOD) disabled.
[4] Self wakeup-timer disabled. Wake-up from deep power-down causes the LPC800 to go through entire reset
process. The wake-up time measured is the time between when a wake-up pin is triggered to wake the
device up from the low power modes and from when a GPIO output pin is set in the reset handler.
14.2 XTAL input
The input voltage to the on-chip oscillators is limited to 1.8 V. If the oscillator is driven by a
clock in slave mode, it is recommended that the input be coupled through a capacitor with
C
i
= 100 pF. To limit the input voltage to the specified range, choose an additional
capacitor to ground C
g
which attenuates the input voltage by a factor C
i
/(C
i
+ C
g
). In slave
mode, a minimum of 200 mV(RMS) is needed.
In slave mode the input clock signal should be coupled by means of a capacitor of 100 pF
(Figure 35
), with an amplitude between 200 mV (RMS) and 1000 mV (RMS). This
corresponds to a square wave signal with a signal swing of between 280 mV and 1.4 V.
The XTALOUT pin in this configuration can be left unconnected.
External components and models used in oscillation mode are shown in Figure 36
and in
Table 25
and Table 26. Since the feedback resistance is integrated on chip, only a crystal
and the capacitances C
X1
and C
X2
need to be connected externally in case of
fundamental mode oscillation (the fundamental frequency is represented by L, C
L
and
Table 24. Typical wake-up times (3.3 V, Temp = 25 °C)
Power modes V
DD
current Wake-up time
Sleep mode (12 MHz)
[1][2]
0.7 mA 2.6 s
Deep-sleep mode
[1][3]
150 A4 s
Power-down mode
[1][3]
0.9 A 50 s
Deep Power-down mode
[4]
170 nA 215 s
Fig 35. Slave mode operation of the on-chip oscillator
/3&
;7$/,1
&
L
S)
&
J
DDD