MC33912BAC Freescale Semiconductor, MC33912BAC Datasheet - Page 75

• Manufacturer Part Number: MC33912BAC
• Description: IC SYSTEM BASIS CHIP 32LQFP
• Manufacturer: Freescale Semiconductor

Specifications of MC33912BAC

• Applications: System Basis Chip
• Current - Supply: 4.5mA
• Voltage - Supply: 5.5 V ~ 27 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 32-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

drive the RST output low for at least 1.0 ms (typical value)
before driving it high.
5.0 V Regulator Low-voltage-Reset (V
against brown outs. If the supply monitor detects that the
voltage at the VDD pin has dropped below the reset threshold
V
temperature, the voltage regulator will be disabled and the
voltage monitoring will issue a VDDOT Flag independently of
the V
Window Watchdog Overflow
window is open, the 33912 will detect an MCU software run-
away and will reset the microcontroller.
Wake-up From Sleep Mode
all wake-up requests from Sleep mode require a power-up/
reset sequence.
External Reset
device to a safe state (same as Reset mode) for as long as
this pin is held low. The RST pin must be held low long
enough to pass the internal glitch filter and get recognized by
the internal reset circuit. This functionality is also active in
Stop mode.
considered.
WAKE-UP CAPABILITIES
Stop) only wake-up sources can bring the device into Normal
mode operation.
interrupt, while in Sleep mode the wake-up is performed by
activating the 5.0 V regulator and resetting the MCU. In both
cases the MCU can detect the wake-up source by accessing
the SPI registers. There is no specific SPI register bit to signal
a CS wake-up or external reset. If necessary this condition is
detected by excluding all other possible wake-up sources.
Wake-up from Wake-up inputs (L1-L4) with cyclic sense
disabled
of external switches and wake-up the MCU (in Sleep or Stop
mode).
Analog Integrated Circuit Device Data
Freescale Semiconductor
RSTTH
After the reset source is removed, the state machine will
In the 33912, four main reset sources exist:
The 5.0 V regulator output V
If the watchdog counter is not properly serviced while its
During Sleep mode, the 5V regulator is not active, hence
The 33912 has a bidirectional reset pin which drives the
After the RST pin is released, there is no extra
Once entered into one of the low-power modes (Sleep or
In Stop mode, a wake-up is signaled to the MCU as an
The wake-up lines are dedicated to sense state changes
DD
the 33912 will issue a reset. In case of over-
voltage.
DD
is continuously monitored
RSTTH
)
t
RST
to be
inputs, the Wake-up Control Register (WUCR) must be
configured with appropriate LxWE inputs enabled or
disabled. The wake-up input’s state is read through the
Wake-up Status Register (WUSR).
before entering low power mode will disable the wake-up
capability of the Lx input
Wake-up from Wake-up inputs (L1-L4) with cyclic sense
timer enabled
period if on one of the four wake-up input lines (L1-L4) a state
change occurs. The HSx switch is activated in Sleep or Stop
modes from an internal timer. Cyclic sense and force wake-
up are exclusive. If cyclic sense is enabled, the force wake-
up can not be enabled.
from Lx inputs, before entering in low power modes (Stop or
Sleep modes), the following SPI set-up has to be performed:
Forced Wake-up
predetermined time spent in Sleep or Stop mode. Cyclic
sense and Forced wake-up are exclusive. If Forced wake-up
is enabled, the Cyclic Sense can not be enabled.
has to be sent before entering in low power modes:
CS Wake-up
wake-up. The CS wake-up does not generate an interrupt,
and is not reported on SPI.
LIN Wake-up
activity on the LIN bus. A dominant pulse larger than t
followed by a dominant to recessive transition will cause a
LIN wake-up. This behavior protects the system from a short
to ground bus condition.
In order to select and activate direct wake-up from Lx
Lx inputs are also used to perform cyclic-sense wake-up.
Note: Selecting an Lx input in the analog multiplexer
The SBCLIN can wake-up at the end of a cyclic sense
In order to select and activate the cyclic sense wake-up
In WUCR: select the Lx input to WU-enable.
In HSCR: enable the desired HSx.
• In TIMCR: select the CS/WD bit and determine the
• Perform Goto Sleep/Stop command.
The 33912 can wake-up automatically after a
To determine the wake-up period, the following SPI set-up
• In TIMCR: select the CS/WD bit and determine the low
• In HSCR: all HSx bits must be disabled.
While in Stop mode, a rising edge on the CS will cause a
While in the low-power mode, the 33912 monitors the
cyclic sense period with CYSTx bits.
power mode period with CYSTx bits.
FUNCTIONAL DEVICE OPERATIONS
OPERATIONAL MODES
PROPWL
33912
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