mc33905s Freescale Semiconductor, Inc, mc33905s Datasheet - Page 39

• Manufacturer Part Number: mc33905s
• Description: System Basis Chip Gen2 With High Speed Can And Lin Interface
• Manufacturer: Freescale Semiconductor, Inc

Vdd off and LP Vdd on).
biasing of external contact swicthes. The contact switch state
can be detected via I/O-1, 2 and 3, and device can wake up
from LP mode.
closed contact switch, in order to minimize consumption via
the contact pull up resistor.
Principle:
from 3 to 512ms (selection in timer B).
duration of T_cson (SPI selectable in INIT register, to 200us,
Analog Integrated Circuit Device Data
Freescale Semiconductor
This function can be used in both Low Power modes (LP
Cyclic sense is the periodic activation of I/O-0, to allow
Cyclic sense is optimized and designed primarily for
A dedicated timer allows to select a cyclic sense period
At end of the period, the I/O-0 will be activated for a
NORMAL MODE
I/O-0 high side active in Normal mode
S3
I/O-0
I/O-1
Upon entering in LP mode, all 3
S1
contact switches are closed.
R
Cyclic sense active time
S2
R
S1
Cyclic sense period
R
S1 closed
Figure 21. Cyclic Sense operation - switch to gnd, wake up by open switch
LOW POWER MODE
CYCLIC SENSE OPERATION DURING LP MODES
I/O-0
I/O-1
I/O-2
I/O-3
I/O-0 high side active during cyclic sense active time
state of I/O-1 low => no wake up
S1 open
High level is detected on I/O-x, and device wakes up.
In LP mode, 1 contact switch is open.
RESET or NORMAL REQUEST MODE
S3
Wake up detected.
R
I/O-1 high => wake up
S2
R
S1
400us, 800us or 1.6ms). The I/O-0 high side transistor or low
side transistor can be activated. The selection is done by the
state of I/O-0 prior to enter in low power mode.
of them is high, the device will detect a wake up. (
to enter in device low power mode. Upon entering LP mode, I/
O-0 should be activated.
and is deglitched for a duration of typ 30us. This mean that I/
O-1 should be in the expected state for a duration longer than
the deglitcher time.
operation, with I/O-0 high side active and I/O-1 wake up in
case of high level.
R
The diagram below (
During the T-cson duration, the I/O-x are monitored. If one
Cyclic sense period is selected by SPI configuration prior
The level of I/O-1 is sense during the I/O-0 active time,
CYCLIC SENSE OPERATION DURING LP MODES
I/O-0
I/O-1
I/O-2
I/O-3
I/O-0
I/O-1
Zoom
Figure 21
FUNCTIONAL DEVICE OPERATION
Wake up event detected
) illustrates the cyclic sense
I/O-1 deglitcher time
Cyclic sense active
time (ex 200us)
(typ 30us)
Figure 21
33904/5
).
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