Chapter 23 Voltage Regulator (S12VREGL3V3V1)
MC9S12XE-Family Reference Manual , Rev. 1.19
828
Freescale Semiconductor
The API Trimming bits APITR[5:0] must be set so the minimum period equals 0.2 ms if stable frequency
is desired.
See
for the trimming effect of APITR.
NOTE
The first period after enabling the counter by APIFE might be reduced by
API start up delay t
sdel
. The API internal RC oscillator clock is not available
if VREG_3V3 is in Shutdown Mode.
It is possible to generate with the API a waveform at an external pin by enabling the API by setting APIFE
and enabling the external access with setting APIEA. By setting APIES the waveform can be selected. If
APIES is set, then at the external pin a clock is visible with 2 times the selected API Period (
).
If APIES is not set, then at the external pin will be a high pulse at the end of every selected period with the
size of half of the min period (
). See device level specification for connectivity.
23.4.9
Resets
This section describes how VREG_3V3 controls the reset of the MCU.The reset values of registers and
signals are provided in
Section 23.3, “Memory Map and Register Definition”
. Possible reset sources are
listed in
23.4.10 Description of Reset Operation
23.4.10.1 Power-On Reset (POR)
During chip power-up the digital core may not work if its supply voltage V
DD
is below the POR
deassertion level (V
PORD
). Therefore, signal POR, which forces the other blocks of the device into reset,
is kept high until V
DD
exceeds V
PORD
. The MCU will run the start-up sequence after POR deassertion.
The power-on reset is active in all operation modes of VREG_3V3.
23.4.10.2 Low-Voltage Reset (LVR)
For details on low-voltage reset, see
Section 23.4.5, “Low-Voltage Reset (LVR)”
.
23.4.11 Interrupts
This section describes all interrupts originated by VREG_3V3.
The interrupt vectors requested by VREG_3V3 are listed in
. Vector addresses and interrupt
priorities are defined at MCU level.
Table 23-12. Reset Sources
Reset Source
Local Enable
Power-on reset
Always active
Low-voltage reset
Available only in Full Performance Mode
Because
of
an
order
from
the
United
States
International
Trade
Commission,
BGA-packaged
product
lines
and
part
numbers
indicated
here
currently
are
not
available
from
Freescale
for
import
or
sale
in
the
United
States
prior
to
September
2010:
S12XE
products
in
208
MAPBGA
packages
