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NUC970 Technical Reference Manual
Publication Release Date: Dec. 15, 2015
- 1202 -
Revision V1.30
NUC97
0
T
E
CHNIC
A
L
RE
F
E
RE
N
CE
MA
NUA
L
Low Speed Mode(200ks/s)
5.32.5.4
Selection of Reference Voltage
5.32.5.5
REF_SEL[2:0]
ADC Analog Reference Pair Selection Signals
00
AGND33 Vs 2.5v buffer output, or VREF input.
01
YM Vs YP
10
XM Vs XP
11
AGND33 Vs AVDD33
Reference voltage is selected very flexibly, and could be selected according to the application.
For battery voltage input, REF_SEL should be set to 00, VREF and AGND.
For 4-wire/5-wire touch Screen Y axis conversion, REF_SEL could be set to 01
For 4-wire/5-wire touch Screen X axis conversion, REF_SEL could be set to 10
Others, for example, VHS inputs a sin wave, rail to rail, REF_SEL should be set to 00 or
11.
Typical Application
5.32.5.6
Battery Voltage Detection
5.32.5.7
Take VBT as input, and select internal buffer
’s output as the reference. For ADC configure
register VBAT_EN (ADC_CONF[8]) should be set to 1.
Core ADC
Core ADC
0.125v to 1.375v
0.125v to 1.375v
7.5k
7.5k
2.5k
2.5k
VBT
VBT
Battery
0.5v to 5.5v
Battery
0.5v to 5.5v
Figure 5.32-4 ADC Battery Voltage Detection Diagram