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TC1784
Fast Analog to Digital Converter (FADC)
User´s Manual
24-6
V1.1, 2011-05
FADC, V2.21
Note: Due to the temperature characteristics of offset and gain of the internal amplifiers
a TUE (total unadjusted error) cannot be specified. The input impedance for
R
p
and
R
n
is defined in the TC1784 Data Sheet.
Note: The analog input lines of the FADC can also be used as input lines for other ADCs.
If both (regular ADC and FADC) are connected to the same pin at the same time,
the input impedances of the analog inputs must be taken into account in order to
minimize signal distortions and measurement errors.
Configuration 0: Channel Not Used (ACRx.ENP = ACRx.ENN = 0)
FADC channel x inputs FAINxP and FAINxN are in a high impedance state. The channel
amplifier of the analog input stage is in power-down mode if both connected input
channels are switched off for measurements.
Configuration 1: Single-ended of FAINxN (ACRx.ENP = 0 and ACRx.ENN = 1)
This configuration enables the single-ended measurement mode for
V
VAREF
/2 - FAINxN:
The positive analog input FAINxP is disconnected is in a high impedance state. The
negative analog input FAINxN is connected to the channel amplifier (input impedance is
determined by
R
n
). The positive input of the channel amplifier is connected to
V
FAREF
/2
(1.65 V with
V
FAREF
= 3.3 V). If the voltage at the negative input FAINxN varies, the
FADC will deliver conversion results as follows (gain = 1 selected by ACRx.GAIN = 00
B
):
•
FAINxN = 0 V: FADC conversion result is 768
•
FAINxN = 3.3 V: FADC conversion result is 256
To cover the full range of the measurement result in this single-ended measurement
mode, a gain of 2 must be selected (ACRx.GAIN = 01
B
). With gain = 2, the FADC will
deliver conversion results as follows:
•
FAINxN = 0 V: FADC conversion result is 1023
•
FAINxN = 3.3 V: FADC conversion result is 0
The voltage at the disconnected positive analog input FAINxP has no influence on the
conversion result.
Configuration 2: Single-ended of FAINxP (ACRx.ENP = 1 and ACRx.ENN = 0)
This configuration enables the single-ended measurement mode for FAINxP -
V
VAREF
/2.
The negative analog input FAINxN is disconnected and in a high impedance state. The
positive analog input FAINxP is connected to the channel amplifier (input impedance is
determined by
R
p
). The negative input of the channel amplifier is connected to
V
FAREF
/2
(1.65 V with
V
FAREF
= 3.3 V). If the voltage at the positive input FAINxP varies, the FADC
will deliver conversion results as follows (gain = 1 selected by ACRx.GAIN = 00
B
):
•
FAINxP = 0 V: FADC conversion result is 256
•
FAINxP = 3.3 V: FADC conversion result is 768
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 ...