Datasheet

LPC84x All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2018. All rights reserved.
Product data sheet Rev. 1.7 — 27 February 2018 72 of 97
NXP Semiconductors
LPC84x
32-bit Arm Cortex-M0+ microcontroller
13.2.1 ADC input impedance
Figure 34 shows the ADC input impedance. In this figure:
• ADCx represents ADC input channel 0.
• ADCy represents ADC input channels 1 to 11.
• R
1
and R
sw
are the switch-on resistance on the ADC input channel.
• If ADC input channel 0 is selected, the ADC input signal goes through R
1
+ R
sw
to the
sampling capacitor (C
ia
).
• If ADC input channels 1 to 11 are selected, the ADC input signal goes through R
sw
to
the sampling capacitor (C
ia
).
• Typical values, R
1
= 2.5 k, R
sw
= 25 
• See Ta b le 11 for C
io
.
• See Ta b le 2 7 for C
ia
.
Fig 34. ADC input impedance
DAC
ADC
R
sw
R
1
C
ia
ADCx
ADCy
C
io
C
io
aaa-017600