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TC65 Terminal Hardware Interface Description
Confidential / Released
3.10.5
Analog-to Digital Converter (ADC)
The two balanced analog inputs are used for measuring external DC voltages in a range of
0V to 5.0V.
Note: Only positive differential voltage can be handled because of the input requirement of
ADC.
Table 16: ADC signal description
Signal name
Pin
ADC1_IN_N
22
ADC1_IN_P
21
ADC2_IN_N
10
ADC2_IN_P
9
GPIO-
Connector
21,9
ADCx_IN_P
22,10
ADCx_IN_N
6V transil diods
for ESD protection
Use the command AT^SRADC described in [1] to configure the analog inputs and to get the
measurement results.
Note: It is necessary to recalculate measurement results because an amplifier is used to
scale down the ADCx_IN input voltage of the TC65 Terminal (5V) to the ADCx_IN input
voltage of the in-built TC65 module (2.4V).
Two parameters (determined and stored by factory) have to be used for offset compensation
and for consideration of gain and tolerances:
Use the command AT^SAADC described in [1] to read out the required parameters:
<ofsx>:
Offset
<ampx> :
Amplification factor (Gain*4096)
To recalculate the exact voltages [mV] measured at the ADCx_IN input use the following
equation:
Value[mV] = (<value> from AT^SRADC - <ofsx>) * <ampx> / 4096
TC65 Terminal_HD_V02.000b
Description
Negative voltage
Positive voltage (must be more positive than ADC1_IN_N)
Negative voltage
Positive voltage (must be more positive than ADC2_IN_N)
475k
0V...5.0V
475k
Figure 13: ADC balanced amplifier
Page 41 of 65
Gain = appr. 0.48
G=2
2x150k
x=1 for Input 1 or 2 for input 2
s
Cellular
Engine
TC65
2,3
ADCx_IN
0V...2.4V
56
AGND
2007-02-19
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