lpc11c12 NXP Semiconductors, lpc11c12 Datasheet - Page 40

• Manufacturer Part Number: lpc11c12
• Description: 32-bit Cortex-m0 Microcontroller; 16/32 Flash, Sram; C_can
• Manufacturer: NXP Semiconductors

NXP Semiconductors
11. Application information
LPC11C12_C14_0
Preliminary 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 15
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 22. 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 LPC11C12/C14
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.
22), 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
16. Since the feedback resistance is integrated on chip, only a crystal
in
g
Rev. 00.05 — 6 May 2010
which attenuates the input voltage by a factor C
Figure 23
X1
15).
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
C g
and C
Table
P
are supplied by the crystal
LPC11C12/C14
6:
i
/(C
© NXP B.V. 2010. All rights reserved.
Figure 23
i
+ C
g
). In slave
L
and
and in
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