MMC2114 MOTOROLA [Motorola, Inc], MMC2114 Datasheet - Page 465

• Manufacturer Part Number: MMC2114
• Description: M CORE Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

MMC2114 • MMC2113 • MMC2112 — Rev. 1.0
MOTOROLA
NOTE:
BYP is maintained for software compatibility but has no functional
benefit on this version of the QADC.
IST[1:0] — Input Sample Time Field
CHAN[5:0] — Channel Number Field
external circuit should be of low source impedance. Loading effects of
the external circuitry need to be considered because the benefits of
the sample amplifier are not present.
The IST field specifies the length of the sample window. The input
sample time can be varied, under software control, to accommodate
various input channel source impedances. Longer sample times
permit more accurate A/D conversions of signals with higher source
impedances.
Table 19-8
The programmable sample time can also be used to adjust queue
execution time or sampling rate by increasing the time interval
between conversions.
The CHAN field selects the input channel number. The CCW channel
field is programmed with the channel number corresponding to the
analog input pin to be sampled and converted. The analog input pin
channel number assignments and the pin definitions vary depending
on whether the QADC multiplexed or non-multiplexed mode is used
by the application. As far as queue scanning operations are
concerned, there is no distinction between an internally or externally
multiplexed analog input.
Freescale Semiconductor, Inc.
For More Information On This Product,
Queued Analog-to-Digital Converter (QADC)
1 = Amplifier bypass mode enabled
0 = Amplifier bypass mode disabled
IST[1:0]
Go to: www.freescale.com
00
01
10
11
shows the four selectable input sample times.
Table 19-8. Input Sample Times
Input sample time = QCLK period
Input sample time = QCLK period
Input sample time = QCLK period
Input sample time = QCLK period
Input Sample Times
Queued Analog-to-Digital Converter (QADC)
2
4
8
16
Register Descriptions
Advance Information
465