MC68HC705SR3 MOTOROLA [Motorola, Inc], MC68HC705SR3 Datasheet - Page 52

• Manufacturer Part Number: MC68HC705SR3
• Description: High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcontroller Units
• Manufacturer: MOTOROLA [Motorola, Inc]

7
7.1
As shown in Figure 7-1, the ADC consists of an analog multiplexer, an 8-bit digital to analog
capacitor array, a comparator and a successive approximation register (SAR).
There are eight options that can be selected by the multiplexer; the AN0 to AN3 input pins, V
V
Control Register. AN0 to AN3 are input points for ADC conversion operations; the others are
reference points which can be used for test purposes. The converter uses V
reference voltages. An input voltage equal to or greater than V
equal to or less than V
must not be exceeded. Each analog input source should use V
be referenced to V
following should be noted:
The ADC reference inputs (V
converter. Control logic drives this D/A converter and the analog output is successively compared
with the selected analog input sampled at the beginning of the conversion. The conversion is
monotonic with no missing codes.
The result of each successive comparison is stored in the successive approximation register
(SAR) and, when the conversion is complete, the contents of the SAR are transferred to the
read-only ADC Data Register ($0F), and the conversion complete flag, COCO, is set in the
ADC Status and Control Register ($0E).
Warning: Any write to the ADC Status and Control Register will abort the current conversion,
At power-on or external reset, both the ADRC and ADON bits are cleared, thus the ADC is
disabled.
MOTOROLA
7-2
RL
, (V
1) V
2) V
3) V
RH
+V
specifications; and
reset the conversion complete flag (COCO) and a new conversion starts on the
selected channel.
RH
RL
RH
RL
ADC Operation
–V
should be equal to or greater than V
should be equal to or less than V
)/4, or (V
RL
RL
Freescale Semiconductor, Inc.
should be equal to or greater than 4 Volts.
for the ratiometric conversions. To maintain full accuracy of the ADC, the
RL
RH
, but greater than V
For More Information On This Product,
+V
ANALOG TO DIGITAL CONVERTER
RH
RL
)/2. Selection is done via the CHx bits in the ADC Status and
and V
Go to: www.freescale.com
RL
) are applied to a precision internal digital to analog
SS
, converts to $00. Maximum and minimum ratings
CC
;
SS
but less than maximum
RH
RH
converts to $FF. An input voltage
as the supply voltage and should
MC68HC05SR3
RH
and V
RL
RH
as
,
TPG