mc33742 Freescale Semiconductor, Inc, mc33742 Datasheet - Page 25

• Manufacturer Part Number: mc33742
• Description: Mc33742 System Basis Chip Sbc With Enhanced High-speed Can Transceiver
• Manufacturer: Freescale Semiconductor, Inc

NORMAL MODE
ON state. All functions are available in this operating mode
(watchdog, wake-up input reading through SPI, HS
activation, and CAN communication). The watchdog timer is
running and must be periodically cleared through SPI.
STOP MODE
pin. The VDD regulator is activated in a special low power
mode supplying only a few mA of current. This maintains
“keep alive” power for the application’s MCU while the MCU
is in a power-saving state (i.e., a MCU’s version of Stop or
Wait). In the Stop mode, the supply current available from
VSUP pin is very low.
either the 33742 side (for example, cyclic sense, forced
wake-up, CAN message, wake-up inputs, and overcurrent on
VDD) or from the MCU side (key wake-up, etc.).
watchdog software may be either running or not running
depending upon selection by SPI (Reset Control Register
[RCR], bit WDSTOP). To clear a running watchdog timer, the
SBC must be awakened using the CS pin (SPI wake-up). In
Stop mode, wake-up is identical to that in Sleep mode, with
the addition of CS and VDD overcurrent wake-up. Refer to
Table
SLEEP MODE
Current consumption from the VSUP pin is cut. In Sleep
mode, the SBC can be awakened by sensing individual level
individual level changes in the L0 : L3 inputs, by cyclic
checking of the L0 : L3 inputs, by the forced wake-up timer, or
from the CAN physical interface upon receiving a CAN
message. When a wake-up occurs, the SBC goes first into
the Reset mode before entering Normal Request mode.
Analog Integrated Circuit Device Data
Freescale Semiconductor
In Normal mode, both the
The V2 regulator is turned OFF by disabling the V2CTRL
Both parts (the SBC or the MCU) can be awakened from
Stop mode is always selected via SPI. In Stop mode, the
In Sleep mode, the VDD and V2 regulators are OFF.
Request
Standby
Normal
Normal
Mode
7, page 25.
Voltage Regulator
HS: Controllable
HS: Controllable
HS Switch
VDD: ON,
VDD: ON,
VDD: ON,
V2: OFF,
HS: OFF
V2: OFF,
V2: ON,
VDD
and V2 regulators are in the
Capabilities
(if Enabled)
Wake-Up
–
–
–
Low for t
Active LOW if WDOG
or V
Same as Normal
Normally HIGH.
DD
then HIGH
RST Pin
occurs
undervoltage
mode
RST
RESET MODE
for t
enters the Normal Request operating mode. The Reset mode
is entered if a reset condition occurs (VDD LOW, watchdog
time-out, or watchdog trigger in a closed window).
NORMAL REQUEST MODE
automatically entered by the SBC after the Reset mode or
after the 33742 wakes up from the Stop mode.
power-up, the SBC enters the Reset mode prior to entering
the Normal Request mode. After a wake-up from the Stop
mode, the 33742 enters the Normal Request mode directly.
regulator is OFF, and the RST pin is HIGH. As soon as the
SBC enters the Normal Request mode, an internal 350 ms
timer is started (parameter t
application’s MCU must address the 33742 via SPI and
configure the TIM1 sub register to select the watchdog
period. This is required of the SBC to stop the 350 ms
watchdog timer and enter the Normal or Standby mode and
to set the watchdog timer configuration.
NORMAL REQUEST ENTERED AND NO
WATCHDOG CONFIGURATION OCCURS
powers up or after a wake-up from Stop mode and no
watchdog configuration occurs before the 350 ms time period
has expired, the device enters the Reset mode. If no
watchdog configuration is performed, the 33742 will cycle
from the Normal Request mode to Reset mode to Normal
Request mode.
from Sleep mode, and no watchdog configuration occurs
while the 33742S is in Normal Request mode, the SBC
returns to the Sleep mode.
Table 7. Table of Operations
DUR
In the Reset mode, the RST pin is LOW and a timer runs
The Normal Request mode is a temporary operating mode
After a wake-up from the Sleep mode or after a device
In Normal Request mode, the VDD regulator is ON, the V2
If the Normal Request mode is entered after the SBC
If the Normal Request mode is entered after a wake-up
RSTDUR
time,
time. After t
If enabled, signal
Temp, CAN, HS)
Same as Normal
Pre-Warning
failure (VDD
INT Pin
mode
–
RSTDUR
FUNCTIONAL DEVICE OPERATION
NRTOUT
Watchdog
Software
Running
Running
has elapsed, the 33742
–
). During this time, the
OPERATIONAL MODES
Low power
TXD / RXD
CAN Cell
–
33742
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