CP3UB26G18NEP National Semiconductor, CP3UB26G18NEP Datasheet - Page 73

• Manufacturer Part Number: CP3UB26G18NEP
• Manufacturer: National Semiconductor

Specifications of CP3UB26G18NEP

• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 128
• Package Type: LQFP
• Lead Free Status / RoHS Status: Not Compliant

15.0 12-Bit Analog to Digital Converter
The integrated 12-bit ADC provides the following features:
! 8-input analog multiplexer
! 8 single-ended channels or 4 differential channels
! External filtering capability
! 12-bit resolution with 11-bit accuracy
! Sign bit
15.1
The ADC module consists of a 12-bit ADC converter and as-
sociated state machine, together with analog multiplexers to
set up signal paths for sampling and voltage references, log-
ic to control triggering of the converter, and a bus interface.
15.1.1
Up to 8 GPIO pins may be configured as 8 singled-ended
analog inputs or 4 differential pairs. Analog/digital data
passes through four main blocks in the ADC module be-
tween the input pins and the CPU bus:
! Input Multiplexer—an analog multiplexer that selects
! Internal/External Multiplexer—an analog multiplexer
among the input channels.
that selects between the output of the Input Multiplexer
and the ADCIN external analog input.
Data Path
FUNCTIONAL DESCRIPTION
Figure 14. Analog to Digital Converter Block Diagram
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! 15-microsecond conversion time
! Support for resistive touchscreen interface
! Internal or external start trigger
! Programmable start delay after start trigger
! Poll or interrupt on done
! 12-Bit ADC—receives the output of the Internal/External
! ADCRESLT Register—makes conversion results from
The configuration of the analog signal paths is controlled by
fields in the ADCGCR register. The Input Multiplexer is con-
trolled by the MUX_CFG field. The Internal/External Multi-
plexer is controlled by the ADCIN bit. The analog
multiplexers for selecting the voltage references used by the
ADC are controlled by the PREF_CFG and NREF_CFG
fields. The low-ohmic drivers used for interface to resistive
touchscreens are controlled by the TOUCH_CFG field.
Multiplexer and performs the analog to digital conver-
sion.
the 12-Bit ADC available to the on-chip bus. The AD-
CRESLT register includes the software-visible end of a 4-
word FIFO used to queue conversion results.
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