MC68HC11KA Motorola, MC68HC11KA Datasheet - Page 49

• Manufacturer Part Number: MC68HC11KA
• Description: 8-Bit Microcontroller
• Manufacturer: Motorola

MC68HC11KA4
MC68HC11KA4TS/D
E CLOCK
Pins AV
V
A multiplexer allows the single A/D converter to select one of 16 analog input signals. Refer to the A/D
converter channel assignment bits CD–CA description.
The A/D converter control logic implements automatic conversion sequences on a selected channel
four times or on a group of four channels once each. A write to the ADCTL register initiates conversions
and, if made while a conversion is in process, a write to ADCTL also halts a conversion operation in
progress.
When the MULT bit is zero, the A/D converter system is configured to perform four consecutive conver-
sions on the single channel specified by the four channel-select bits (CD–CA). When the MULT bit is
one, the A/D system is configured to perform conversions on each channel in the group of four channels
specified by the CD and CC channel select bits. Refer to Table 8.
When the SCAN bit is zero, four conversions are performed in the desired channel group, once each,
to fill the four result registers. When SCAN is one, conversions continue channel-by-channel in the de-
sired group with the result registers being updated continually as new data becomes available.
RL
ANALOG
INPUT
PIN
provide the reference supply voltage inputs.
0
* THIS ANALOG SWITCH IS CLOSED ONLY DURING THE 12-CYCLE SAMPLE TIME.
DD
CHANNEL, UPDATE
CONVERT FIRST
SAMPLE ANALOG INPUT
and AV
Figure 15 Timing Diagram for a Sequence of Four A/D Conversions
PROTECTION
ADR1
< 2 pF
Figure 16 Electrical Model of an Analog Input Pin (Sample Mode)
DEVICE
12 E CYCLES
INPUT
SS
provide the supply voltage to the digital portion of the A/D converter. Pins V
+ ~20V
– ~0.7V
32
CONVERT SECOND
CHANNEL, UPDATE
ADR2
+ ~12V
– ~0.7V
DUMMY N-CHANNEL
CYCLES
OUTPUT DEVICE
MSB
4
SUCCESSIVE APPROXIMATION SEQUENCE
BIT 6
CYC
64
2
BIT 5
CYC
CHANNEL, UPDATE
CONVERT THIRD
2
BIT 4
CYC
ADR3
2
BIT 3
CYC
2
DIFFUSION/POLY
JUNCTION
LEAKAGE
400 nA
COUPLER
BIT 2
CYC
2
96
4 K
BIT 1
CYC
CONVERT FOURTH
CHANNEL, UPDATE
2
CYC
LSB
ADR4
2
~ 20 pF
*
CYC
END
2
CAPACITANCE
V
RL
128 — E CYCLES
ANALOG INPUT PIN
DAC
MOTOROLA
A/D CONVERSION TIM
RH
and
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