Bandgap
reference
ADC REFSEL
ADC reference
ADCREFIN
F280x DSP
ADCRESEXT
(A)
ADCREFP
(A)
ADCREFM
(A)
ADC LO
2.048-V reference
Analog ground
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ADC Circuit
455
SPRUI07–March 2020
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Analog-to-Digital Converter (ADC)
7.2.3 Reference Selection
By default, an internally generated bandgap voltage reference is selected to supply the ADC logic.
Based on customer application requirements, the ADC logic may be supplied by an external voltage
reference. The ADC will accept 2.048 V, 1.5 V, or 1.024 V on the ADCREFIN pin. The value of the
ADCREFSEL register determines the reference source selected.
If the internal reference option is chosen, the ADCREFIN pin can be left connected to the selected source,
left floating, or grounded. Regardless of which option is chosen, the external circuit for the ADCRESEXT,
ADCREFP, and ADCREFM pins is the same.
The external reference voltage of 2.048 V was chosen to match industry standard reference components.
These components are available in various temperature ratings. A recommended Texas Instruments part
is REF3020AIDBZ.
Figure 7-5. External Bias for 2.048-V External Reference
NOTE: For component values, see the TMS320F2833x, TMS320F2823x Digital Signal Controllers (DSCs) Data
Manual.
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