Freescale Semiconductor, Inc.
Ana log Sub syste m
CP2EN
The CP2EN enable bit controls power to voltage comparator 2 in the
analog subsystem. Powering down a comparator will drop the supply
current by about 100 µA. This bit is cleared by a reset of the device.
1 = Writing a logical one powers up voltage comparator 2
0 = Writing a logical zero powers down voltage comparator 2
NOTE: Voltage comparators power up slower than digital logic; and their
outputs may go through indeterminate states which might set their
respective flags (CPF1, CPF2). It is therefore recommended to power up
the charge current source first (ISEN); then to power up any
comparators, and finally clear the flag bits by writing a logic one to the
respective CPFR1 or CPFR2 bits in the ACR.
CP1EN
The CP1EN enable bit will power down the voltage comparator 1 in
the analog subsystem. Powering down a comparator will drop the
supply current by about 100 µA. This bit is cleared by a reset of the
device.
1 = Writing a logical one powers up voltage comparator 1
0 = Writing a logical zero powers down voltage comparator 1
ISEN
The ISEN enable bit will power down the charge current source and
disable the discharge device in the analog subsystem. Powering
down the current source will drop the supply current by about 200 µA.
This bit is cleared by a reset of the device.
1 = Writing a logical one powers up the ramping current source and
enables the discharge device on the PB0/AN0 pin.
0 = Writing a logical zero powers down the ramping current source
and disables the discharge device on the PB0/AN0 pin.
NOTE: The analog subsystem has support circuitry which draws about 80 µA of
current. This current will be powered down if both comparators and the
charge current source are powered down (ISEN, CP1EN, and CP2EN
all cleared). Powering up either comparator or the charge current source
will activate the support circuitry.
General Release Specification
MC68HC705JJ7/MC68HC705JP7 — Rev. 3.0
Analog Subsystem
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