![Infineon Technologies TC1784 User Manual Download Page 2117](http://html.mh-extra.com/html/infineon-technologies/tc1784/tc1784_user-manual_20554462117.webp)
TC1784
Analog to Digital Converter (ADC)
User´s Manual
23-11
V1.1, 2011-05
ADC, V1.3
23.1.8
Electrical Models
Each conversion of an analog input voltage into a digital value consists of two
consecutive phases. During the sample phase, the input voltage is sampled and
prepared for the following conversion phase. A simplified model for the sample phase
describes the input signal path, whereas a second simplified model for the conversion
phase is related to the reference voltage handling.
23.1.8.1 Input Signal Path
The ADC kernel in the TC1784 is based on one switched capacitor field for
measurement with a total capacity represented by C
AIN
and a small static capacitor at
each input pin. During the sample phase, the capacitor field C
AIN
is connected to one of
the analog input CHx via an input multiplexer. The multiplexer is modeled by ideal
switches and series resistors R
AIN
. Only the switch to the selected analog input is closed
during the sample phase. During the conversion phase or while no conversion is running
(ADC is idle), all switches are open. The voltage at the analog input channel CHx is
represented by V
AINx
.
Figure 23-4 Signal Path Model
A simplified model for the analog input signal path is given in
. An analog
voltage source (value V
S
) with an internal impedance of R
EXT
delivers the analog input
that should be converted.
During the sample phase the corresponding switch is closed and the capacitor field C
AIN
is charged. Due to the low-pass behavior of the resulting RC combination, the voltage
V
C
to be actually converted does not immediately follow V
S
. The value R
EXT
of the analog
voltage source and the desired precision of the conversion strongly define the required
length of the sample phase.
To reduce the influence of R
EXT
and to filter input noise, it is recommended to introduce
ADC_signal_path_model
ADC kernel
...
...
C
AIN
R
AIN
V
AGND
CHx
CH0
CH15
C
EXT
V
AINx
R
EXT
V
S
V
C
Summary of Contents for TC1784
Page 1: ...User s Manual V1 1 2011 05 Microcontrollers TC1784 32 Bit Single Chip Microcontroller ...
Page 3: ...User s Manual V1 1 2011 05 Microcontrollers TC1784 32 Bit Single Chip Microcontroller ...
Page 950: ...TC1784 Direct Memory Access Controller DMA User s Manual 11 132 V1 1 2011 05 DMA V3 03 ...
Page 1949: ...TC1784 General Purpose Timer Array GPTA v5 User s Manual 21 297 V1 1 2011 05 GPTA v5 V1 14 ...
Page 2350: ...w w w i n f i n e o n c o m Published by Infineon Technologies AG Doc_Number ...