mc33662 Freescale Semiconductor, Inc, mc33662 Datasheet - Page 24

• Manufacturer Part Number: mc33662
• Description: Lin 2.1 / Saej2602-2, Lin Physical Layer
• Manufacturer: Freescale Semiconductor, Inc

FUNCTIONAL DESCRIPTION
FUNCTIONAL PIN DESCRIPTION
Rate exit (See
Rate at room and hot temperature.
DATA INPUT PIN (TXD)
of the LIN output. When TXD is LOW (dominant), LIN output
is LOW; when TXD is HIGH (recessive), the LIN output
transistor is turned OFF. TXD pin thresholds are 3.3 V and
5.0 V compatible.
recessive state if the input pin is left floating.
(typical value), the LIN transmitter goes automatically into
recessive state.
DATA OUTPUT PIN (RXD)
state of the LIN bus voltage.
reported by a high voltage on RXD; LIN LOW (dominant) is
reported by a low voltage on RXD.
Figure
interface. The low level is fixed. The high level is dependent
on EN voltage. If EN is set at 3.3 V, RXD V
is set at 5.0 V, RXD V
event is recognized from the WAKE pin or from the LIN bus
pin, RXD is pulled LOW to report the wake-up event. An
external pull-up resistor may be needed.
ENABLE INPUT PIN (EN)
If EN = 1, the interface is in Normal mode, TXD to LIN after
t
pin thresholds are 3.3 V and 5.0 V compatible. RXD V
24
33662
FIRST_DOM
RXD
The TXD input pin is the MCU interface to control the state
This pin has an internal pull-up current source to force the
If the pin stays low (dominant sate) more than 5.0 ms
RXD output pin is the MCU interface, which reports the
In Normal or Slow baud rate, LIN HIGH (recessive) is
The RXD output structure is a tristate output buffer (See
The RXD output pin is the receiver output of the LIN
In Sleep mode, RXD is high-impedance. When a wake-up
EN input pin controls the operation mode of the interface.
28).
delay and LIN to RXD paths are both active. EN
Figure
Figure 28. RXD Interface
LIN_RXD
OH
23). The device enters into Fast Baud
is 5.0 V.
X 1
EN_RXD
Receiver
Control
200 kΩ
Slope
EN
OH
30 k
VSUP
Ω
is 3.3 V. If EN
OH
LIN
level follows EN pin high level. The device enters the Sleep
mode by setting EN LOW for a delay higher than t
typ. value) and if the WAKE pin state doesn’t change during
this delay (see
allows the device to enter into the Fast Baud Rate mode of
operation (see
INHIBIT OUTPUT PIN (INH)
power MOSFET. The pin has two possible main functions. It
can be used to control an external switchable voltage
regulator having an inhibit input. It can also be used to drive
the LIN bus external resistor in the master node application,
thanks to its high drive capability. This is illustrated in
Figure 30
inhibit input is connected to INH, the regulator will be
disabled. If the master node pull-up resistor is connected to
INH, the pull-up resistor will be unpowered and left floating.
off and the LIN transmitter and receiver are in recessive state.
in order to improve EMC performances.
WAKE INPUT PIN (WAKE)
device from the Sleep mode. WAKE is usually connected to
an external switch in the application.
wake-up from both HIGH to LOW or LOW to HIGH
transitions. When entering into Sleep mode, the device
monitors the state of the WAKE pin and stores it as a
reference state. The opposite state of this reference state will
be the wake-up event used by the device to enter again into
Normal mode.
Delay Time (t
lower than t
will go into Awake mode (See
event due to parasitic pulses (See
pin input structure exhibits a high-impedance, with extremely
low input current when voltage at this pin is below 27 V. Two
serial resistors should be inserted in order to limit the input
current mainly during transient pulses and ESD. The total
recommended resistor value is 33 kΩ. An external 10 to
100 nF capacitor is advised for better EMC and ESD
performances.
wake-up function is not used, WAKE should be connected to
ground to avoid a false wake-up.
A combination of the logic levels on the EN and TXD pins
The INH output pin is connected to an internal high side
In Sleep mode, INH is turned OFF. If a voltage regulator
In case of a INH thermal shutdown, the high side is turned
An external 10 to 100 pF capacitor on INH pin is advised
The WAKE pin is a high voltage input used to wake-up the
The WAKE pin has a special design structure and allows
If the Wake pin state changes during the Sleep mode
An internal filter is implemented to avoid a false wake-up
Important The WAKE pin should not be left open. If the
and 31.
WF
SD
, the device will not enter the Sleep mode, but
Figure
Figure
) or before EN goes low with a deglitcher
22).
25).
Analog Integrated Circuit Device Data
Figure
Figure 15
Freescale Semiconductor
26).
and 18). WAKE
SD
(70 µs