MC68HC711PH8 Motorola, MC68HC711PH8 Datasheet - Page 176

• Manufacturer Part Number: MC68HC711PH8
• Description: High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcomputer Unit
• Manufacturer: Motorola

9
9.1.1
The multiplexer selects one of 16 inputs for conversion. Input selection is controlled by the value
of bits CD – CA in the ADCTL register. The eight port E pins are fixed-direction analog inputs to
the multiplexer, and additional internal analog signal lines are routed to it.
Port E pins can also be used as digital inputs (see Section 4). Digital reads of port E pins should
be avoided during the sample portion of an A/D conversion cycle, when the gate signal to the
N-channel input gate is on. Because no P-channel devices are directly connected to either input
pins or reference voltage pins, voltages above V
current and voltage should be limited according to maximum ratings. Refer to Figure 9-2, which is
a functional diagram of an input pin.
MOTOROLA
9-2
PE0/
PE1/
PE2/
PE3/
PE4/
PE5/
PE6/
PE7/
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
Multiplexer
ADR1 - A/D result 1
Analog
MUX
Figure 9-1 A/D converter block diagram
ANALOG-TO-DIGITAL CONVERTER
Result
ADR2 - A/D result 2
Successive approximation
with sample and hold
8-bit capacitive DAC
register and control
Result register interface
DD
ADR3 - A/D result 3
do not cause a latchup problem, although
ADR4 - A/D result 4
SCAN
MULT
CCF
CD
CC
CB
CA
0
VRH
VRL
MC68HC11PH8
data bus
Internal
TPG