MC9S12T64 Datasheet, PDF (512/608 Pages) Motorola, Inc – Specification

Freescale Semiconductor, Inc.
Analog to Digital Converter (ATD)
When not sampling, the sample and hold machine disables its own
clocks. The analog electronics still draw their quiescent current. The
power down (ADPU) bit must be set to disable both the digital clocks and
the analog power consumption.
The input analog signals are unipolar and must fall within the potential
range of VSSA to VDDA.
Analog Input
Multiplexer
The analog input multiplexer connects one of the 8 external analog input
channels to the sample and hold machine.
Sample Buffer
Amplifier
The sample amplifier is used to buffer the input analog signal so that the
storage node can be quickly charged to the sample potential.
Analog-to-Digital
(A/D) Machine
The A/D Machine performs analog to digital conversions. The resolution
is program selectable at either 8 or 10 bits. The A/D machine uses a
successive approximation architecture. It functions by comparing the
stored analog sample potential with a series of digitally generated
analog potentials. By following a binary search algorithm, the A/D
machine locates the approximating potential that is nearest to the
sampled potential.
When not converting the A/D machine disables its own clocks. The
analog electronics still draws quiescent current. The power down
(ADPU) bit must be set to disable both the digital clocks and the analog
power consumption.
Only analog input signals within the potential range of V_RL to V_RH (A/D
reference potentials) will result in a non-railed digital output codes.
Digital Sub-block
This subsection explains some of the digital features in more detail. See
register descriptions for all details.
External Trigger
Input (ETRIG)
The external trigger feature allows the user to synchronize ATD conversions to
the external environment events rather than relying on software to signal the
ATD module when ATD conversions are to take place. The input signal (ATD
channel 7) is programmable to be edge or level sensitive with polarity control.
MC9S12T64Revision 1.1.1
Analog to Digital Converter (ATD)
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