TM4C1292NCZAD Datasheet, PDF (1064/1844 Pages) Texas Instruments – Tiva Microcontroller

Analog-to-Digital Converter (ADC)
Figure 15-7. ADC Input Equivalency
Zs
Rs
Pin
V_S
Cs
V_ADCIN
V_DD
ESD
Clamp
Input PAD
Equivalent
Circuit
Z_ADC
R_ADC
I_L
Tiva™ Microcontroller
12-bit
SAR ADC
Converter
12-bit
Word
Pin
Input PAD
R_ADC
Equivalent
Circuit
Pin
Input PAD
R_ADC
Equivalent
Circuit
C_ADC
The ADC operates from both the 3.3-V analog and 1.2-V digital power supplies. The ADC clock can
be configured to reduce power consumption when ADC conversions are not required (see “System
Control” on page 239). The analog inputs are connected to the ADC through specially balanced input
paths to minimize the distortion and cross-talk on the inputs. Detailed information on the ADC power
supplies and analog inputs can be found in “Analog-to-Digital Converter (ADC)” on page 1815.
15.3.4.1
Voltage Reference
The ADC uses internal signals VREFP and VREFN as references to produce a conversion value
from the selected analog input. VREFP can be connected to either VREFA+ or VDDA and VREFN
can be connected to either VREFA- or GNDA as configured by the VREF bit in the ADC Control
(ADCCTL) register, as shown in Figure 15-8.
Figure 15-8. ADC Voltage Reference
VDDA
VREFA+
VREFA-
GNDA
VREFP
Voltage reference
selected using the
VREF field in the
ADCCTL register
VREFN
ADC
1064
Texas Instruments-Production Data
June 18, 2014