MC68HC912DG128 Datasheet, PDF (176/452 Pages) Motorola, Inc – Microcontrollers

Clock Functions
Freescale Semiconductor, Inc.
Technical Data
176
PLLON — Phase Lock Loop On
0 = Turns the PLL off.
1 = Turns on the phase lock loop circuit. If AUTO is set, the PLL will
lock automatically.
Cannot be cleared when BCSP = 1 (PLL selected as bus clock).
Forced to 0 when VDDPLL is at VSS level. In limp-home mode, the
output of PLLON is forced to 1, but the PLLON bit reads the latched
value.
AUTO — Automatic Bandwidth Control
0 = Automatic Mode Control is disabled and the PLL is under
software control, using ACQ bit.
1 = Automatic Mode Control is enabled. ACQ bit is read only.
Automatic bandwidth control selects either the high bandwidth
(acquisition) mode or the low bandwidth (tracking) mode depending
on how close to the desired frequency the VCO is running. See
Electrical Specifications.
ACQ — Not in Acquisition
If AUTO = 1 (ACQ is Read Only)
0 = PLL VCO is not within the desired tolerance of the target
frequency. The loop filter is in high bandwidth, acquisition
mode.
1 = After the phase lock loop circuit is turned on, indicates the PLL
VCO is within the desired tolerance of the target frequency.
The loop filter is in low bandwidth, tracking mode.
If AUTO = 0
0 = High bandwidth PLL loop selected
1 = Low bandwidth PLL loop selected
PSTP — Pseudo-STOP Enable
0 = Pseudo-STOP oscillator mode is disabled
1 = Pseudo-STOP oscillator mode is enabled
In Pseudo-STOP mode, the oscillator is still running while the MCU is
maintained in STOP mode. This allows for a faster STOP recovery
and reduces the mechanical stress and aging of the resonator in case
frequent STOP conditions at the expense of a slightly increased
power consumption.
MC68HC912DG128 — Rev 3.0
Clock Functions
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