NXP Semiconductors LPC5411 Series, Product Data Sheet

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LPC5411x All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2018. All rights reserved.
Product data sheet Rev. 2.1 — 9 May 2018 83 of 105
NXP Semiconductors
LPC5411x
32-bit ARM Cortex-M4/M0+ microcontroller
[1] Characterized through simulation. Not tested in production.
[2] The ADC default sampling time is 2.5 ADC clock cycles. To match a given analog source output
impedance, the sampling time can be extended by adding up to seven ADC clock cycles for a maximum
sampling time of 9.5 ADC clock cycles. See the TSAMP bits in the ADC CTRL register.
[3] Z
o
= analog source output impedance.
12.2.1 ADC input impedance
Figure 28 shows the ADC input impedance. In this figure:
•
ADCx represents slow ADC input channels 6 to 11.
• ADCy represents fast ADC input channels 0 to 5.
•
R
1
and R
sw
are the switch-on resistance on the ADC input channel.
•
If fast channels (ADC inputs 0 to 5) are selected, the ADC input signal goes through
R
sw
to the sampling capacitor (C
ia
).
• If slow channels (ADC inputs 6 to 11) are selected, the ADC input signal goes through
R
1
+ R
sw
to the sampling capacitor (C
ia
).
•
Typical values, R
1
= 487

, R
sw
= 278

•
See Table 20 for C
io
.
• See Table 37 for C
ia
.
ADC inputs ADC_11 to ADC_6 (slow channels); ADC resolution = 10 bit
t
s
sampling time Z
o
< 0.05 k Ω
[3]
35 - - ns
0.05 k Ω

Z
o
< 0.1 k Ω 38 - - ns
0.1 k Ω

Z
o
< 0.2 k Ω 40 - - ns
0.2 k Ω

Z
o
< 0.5 k Ω 46 - - ns
0.5 k Ω

Z
o
< 1 k Ω 61 - - ns
1 k Ω

Z
o
< 5 k Ω 86 - - ns
ADC inputs ADC_11 to ADC_6 (slow channels); ADC resolution = 8 bit
t
s
sampling time Z
o
< 0.05 k Ω
[3]
27 - - ns
0.05 k Ω

Z
o
< 0.1 k Ω 29 - - ns
0.1 k Ω

Z
o
< 0.2 k Ω 32 - - ns
0.2 k Ω

Z
o
< 0.5 k Ω 36 - - ns
0.5 k Ω

Z
o
< 1 k Ω 48 - - ns
1 k Ω

Z
o
< 5 k Ω 69 - - ns
ADC inputs ADC_11 to ADC_6 (slow channels); ADC resolution = 6 bit
t
s
sampling time Z
o
< 0.05 k Ω
[3]
20 - - ns
0.05 k Ω

Z
o
< 0.1 k Ω 22 - - ns
0.1 k Ω

Z
o
< 0.2 k Ω 23 - - ns
0.2 k Ω

Z
o
< 0.5 k Ω 26 - - ns
0.5 k Ω

Z
o
< 1 k Ω 36 - - ns
1 k Ω

Z
o
< 5 k Ω 51 - - ns
Table 38. ADC sampling times
…continued
[1]
T
amb
= -40

C to 85

C; 1.62 V

V
DDA

3.6 V; 1.62 V

V
DD

3.6 V
Symbol Parameter Conditions Min Typ Max Unit