Adc Introduction; Adc Operation; Adc Inputs; Adc Block Diagram - Texas Instruments CC253x User Manual

www.ti.com

12.1 ADC Introduction

The ADC supports up to 14-bit analog-to-digital conversion with up to 12 bits ENOB (Effective Number Of
Bits). It includes an analog multiplexer with up to eight individually configurable channels and a reference
voltage generator. Conversion results can be written to memory through DMA. Several modes of operation
are available.
The main features of the ADC are as follows:
• Selectable decimation rates which also set the effective resolution (7 to 12 bits).
• Eight individual input channels, single-ended or differential
• Reference voltage selectable as internal, external single-ended, external differential, or AVDD5
• Interrupt request generation
• DMA triggers at end of conversions
• Temperature sensor input
• Battery measurement capability
Internal Reference Voltage
AIN6–AIN7

12.2 ADC Operation

This section describes the general setup and operation of the ADC and describes the use of the ADC
control and status registers accessed by the CPU.

12.2.1 ADC Inputs

The signals on the port-0 pins can be used as ADC inputs. In the following, these port pins are referred to
as the AIN0–AIN7 pins. The input pins AIN0–AIN7 are connected to the ADC.
It is possible to configure the inputs as single-ended or differential inputs. In the case where differential
inputs are selected, the differential inputs consist of the input pairs AIN0–AIN1, AIN2–AIN3, AIN4–AIN5,
and AIN6–AIN7. Note that no negative supply can be applied to these pins, nor a supply higher than VDD
(unregulated power). It is the difference between the pins of each pair that is converted in differential
mode.
In addition to the input pins AIN0–AIN7, the output of an on-chip temperature sensor can be selected as
an input to the ADC for temperature measurements. In order to do so, the registers TR0.ADCTM and
ATEST.ATESTCTRL must be set as described in the register descriptions in
Section 23.15.3 (CC253x) or
It is also possible to select a voltage corresponding to AVDD5 divided by 3 as an ADC input. This input
allows the implementation of, for example, a battery monitor in applications where this feature is required.
Note that the reference in this case must not be dependent on the battery voltage; for instance, the
AVDD5 voltage must not be used as a reference.
SWRU191F – April 2009 – Revised April 2014
Submit Documentation Feedback
AIN0
AIN7
Input
VDD/3
Mux
TMP_ SENSOR
AIN7
Ref
Mux
AVDD
Figure 12-1. ADC Block Diagram
Section 24.1 (CC2540), or
Copyright © 2009–2014, Texas Instruments Incorporated
Sigma-Delta Decimation
Modulator Filter
Clock Generation
and
Control
Section 12.2.10
Section 25.12 (CC2541).
ADC Introduction
B0304-01
and
133
ADC