LPC1111 NXP [NXP Semiconductors], LPC1111 Datasheet - Page 48

• Manufacturer Part Number: LPC1111
• Description: 32-bit ARM Cortex-M0 microcontroller; up to 32 kB flash and 8 kB SRAM
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
11. Application information
LPC1111_12_13_14_1
Product data sheet
11.1 ADC usage notes
11.2 XTAL input
The following guidelines show how to increase the performance of the ADC in a noisy
environment beyond the ADC specifications listed in
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
capacitor to ground C
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
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
Table 17
and the capacitances C
fundamental mode oscillation (the fundamental frequency is represented by L, C
R
not be larger than 7 pF. Parameters F
manufacturer (see
Fig 24. Slave mode operation of the on-chip oscillator
•
•
•
•
i
S
= 100 pF. To limit the input voltage to the specified range, choose an additional
). Capacitance C
The ADC input trace must be short and as close as possible to the LPC1111/12/13/14
chip.
The ADC input traces must be shielded from fast switching digital signals and noisy
power supply lines.
Because the ADC and the digital core share the same power supply, the power supply
line must be adequately filtered.
To improve the ADC performance in a very noisy environment, put the device in Sleep
mode during the ADC conversion.
24), with an amplitude between 200 mV(RMS) and 1000 mV(RMS). This
and
Table
All information provided in this document is subject to legal disclaimers.
Table
P
18. Since the feedback resistance is integrated on chip, only a crystal
in
g
which attenuates the input voltage by a factor C
Rev. 01 — 16 April 2010
Figure 25
X1
17).
and C
X2
represents the parallel package capacitance and should
need to be connected externally in case of
OSC
XTALIN
LPC1xxx
C i
100 pF
, C
L
, R
S
002aae788
32-bit ARM Cortex-M0 microcontroller
C g
and C
LPC1111/12/13/14
Table
P
are supplied by the crystal
8:
i
/(C
© NXP B.V. 2010. All rights reserved.
Figure 25
i
+ C
g
). In slave
L
and
and in
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