MC68HC705JJ7 Datasheet, PDF (76/164 Pages) Freescale Semiconductor, Inc – Microcontrollers

Analog Subsystem
Therefore, input voltages cannot be resolved if they are less than the sum
of the AV_SS offset and the comparator offset, because they will always yield
a low output from the comparator.
Table 8-2. Channel Select Bus Combinations
Analog Multiplex Register
Channel Select Bus Connected to:
VREF
MUX4
MUX3
MUX2
MUX1 V_DD
PB4/AN4/
TCMP
PB3/AN3/
TCAP
PB2/AN2
PB1/AN1 V_SS
0
0
0
0
0
Hi-Z
Hi-Z
Hi-Z
Hi-Z
Hi-Z
On
X⁽¹⁾
0
0
0
1
Hi-Z
Hi-Z
Hi-Z
Hi-Z
On
Hi-Z
X⁽¹⁾
0
0
1
0
Hi-Z
Hi-Z
Hi-Z
On
Hi-Z
Hi-Z
X⁽¹⁾
0
0
1
1
Hi-Z
Hi-Z
Hi-Z
On
On
Hi-Z
X⁽¹⁾
0
1
0
0
Hi-Z
Hi-Z
On
Hi-Z
Hi-Z
Hi-Z
X⁽¹⁾
0
1
0
1
Hi-Z
Hi-Z
On
Hi-Z
On
Hi-Z
X⁽¹⁾
0
1
1
0
Hi-Z
Hi-Z
On
On
Hi-Z
Hi-Z
X⁽¹⁾
0
1
1
1
Hi-Z
Hi-Z
On
On
On
Hi-Z
X⁽¹⁾
1
0
0
0
Hi-Z
On
Hi-Z
Hi-Z
Hi-Z
Hi-Z
X⁽¹⁾
1
0
0
1
Hi-Z
On
Hi-Z
Hi-Z
On
Hi-Z
X⁽¹⁾
1
0
1
0
Hi-Z
On
Hi-Z
On
Hi-Z
Hi-Z
X⁽¹⁾
1
0
1
1
Hi-Z
On
Hi-Z
On
On
Hi-Z
X⁽¹⁾
1
1
0
0
Hi-Z
On
On
Hi-Z
Hi-Z
Hi-Z
X⁽¹⁾
1
1
0
1
Hi-Z
On
On
Hi-Z
On
Hi-Z
X⁽¹⁾
1
1
1
0
Hi-Z
On
On
On
Hi-Z
Hi-Z
X⁽¹⁾
1
1
1
1
Hi Z
On
On
On
On
Hi Z
1. Don/t care
8.3 Analog Control Register
The analog control register (ACR) controls the power-up, interrupt, and flag operation. The analog
subsystem draws current while it is operating. The resulting power consumption can be reduced
by powering down the analog subsystem when not in use (refer to 15.5 Supply Current Characteristics
(V_DD = 4.5 to 5.5 Vdc)). This can be done by clearing three enable bits (ISEN, CP1EN, and CP2EN) in
the ACR at $001D. Since these bits are cleared following a reset, the voltage comparators and the charge
current source will be powered down following a reset of the device.
The control bits in the ACR are shown in Figure 8-5. All the bits in this register are cleared by a reset of
the device.
MC68HC705JJ7 • MC68HC705JP7 Advance Information Data Sheet, Rev. 4.1
76
Freescale Semiconductor