MC33399 Motorola, MC33399 Datasheet - Page 5

• Manufacturer Part Number: MC33399
• Description: Automotive Local Interconnect Network Physical Interface
• Manufacturer: Motorola

VSUP Supply Pin
a serial diode for reverse battery protection. The DC operating
voltage is from 7 to 27V. This pin sustains standard
automotive voltage conditions such as 27V DC during jump
start conditions and 40V during load dump. An under voltage
reset circuitry is implemented to disable the transmission path
(from Tx to LIN) when Vsup is falling below 7V in order to
avoid false bus message. Supply current in sleep mode is
20uA typical.
GND Ground Pin
MC33399 does not have significant current consumption on
the LIN bus pin when in recessive state (less than 100uA is
sourced from LIN bus pin, which create 100mV drop voltage
from the 1 kohms LIN bus pull up resistor), for dominant state
the pull up resistor should be always active.
Vsup>9V. Below 9V Vsup, ground shift can reduce Vsup
value below the minimum Vsup operation of 7V.
LIN Bus Pin
receiver.
Transmitter Characteristics
limitation and thermal shutdown. An internal pull up resistor
with a serial diode structure is integrated, so no external pull-
up components are required for the application in a slave
node. An additional pull up resistor of 1k
when the device is used in the master node.
18V) without no current other than the pull up resistance. This
pin exhibit no reverse current from the LIN bus line to VSUP,
even in case of GND shift or Vbat disconnection. LIN
thresholds are compatible LIN Protocol Specification.
from dominant to recessive are controlled to 2V/us typical.
The symmetry between rise and fall time is also guaranteed.
impedance parasitic capacitor has to be charged up to Vsup,
and this is done by the total system pull up current resistors. In
order to guarantee the rise time is within the specification,
maximum bus capacitance should not exceed 10nF with bus
total pull up resistance less than 1kOhm.
Receiver Characteristics
supply pin. Typical threshold is 50%, with a hysteresis
between 5 and 10% of Vsupply.
Tx Input Pin
output. When Tx is low, LIN output is low, when Tx is high, LIN
output transistor is turned off.
in order to set the bus in recessive state in case the micron
controller could not control it during system power up or down
for instance. During the Sleep mode the pull-up is turned off.
Device power supply pin. It is connected to battery through
Device gnd connection.
In case ground disconnection at the module level, the
Gnd shift: the MC33399 handle ground shift up to 3V for
This I/O pin represents the single-wire bus transmitter and
The driver is a low side transistor with internal current
Voltage can go from +40V down to 18V DC below GND (-
The fall time, from recessive to dominant and the rise time
When going from dominant to recessive the bus
The receiver thresholds are ratiometric with the device
This pin is the MCU interface to control the state of the LIN
This pin has an internal pull up current source internal 5V
Automotive “Local Interconnect Network” Physical Interface
Freescale Semiconductor, Inc.
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FUNCTIONAL DESCRIPTION
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MC33399
Rx Output Pin
LIN bus voltage. LIN high (recessive) is reported by a high
level on Rx, LIN low (dominant) is reported by a low voltage on
Rx. Rx output structure is a CMOS type push-pull output
stage.
EN Input Pin (Enable)
EN=1, the interface is in normal mode, with transmission path
from Tx to LIN and from LIN to Rx both active.
mode, and no transmission is possible. In sleep mode the LIN
bus pin is hold at Vsup through the bus pull up resistors and
pull up current sources. The device can transmit only after
being waked up (see INH pin description).
battery voltage (through VSUP pin). Supply current is 20uA
typical. Setting the ENABLE pin to low will turn the INHIBIT to
high impedance. EN pin has an internal 20uA pull down
current source to ensure the device is in sleep mode if EN
floats.
INH Output Pin
regulator having an inhibit input. The inhibit pin is a high side
switch structure to Vsup. When the device is in normal mode,
inhibit high side switch is turned on and the external voltage
regulator is activated. When the device is in sleep mode, the
inhibit switch is turned off and disables the voltage regulator (if
this feature is used).
pin to Vsup level. Wake up output current capability is limited
to 280uA. INH pin can also drive an external transistor
connected to an MCU IRQ or XIRQ input to generate an
interrupt. Refer to typical application, figure 7.
Wake Input Pin
from Sleep mode. Wake is usually connected to an external
switch in the application. The typical wake thresholds are
Vsup/2.
from both high to low or low to high transitions. When entering
into the Sleep mode, the LIN monitors the state of the wake
pin and stores it as 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.
time delay). Wake pin input structure exhibits a high
impedance, with extremely low input current when voltage at
this pin is below 14V. When voltage at Wake pin exceed 14V
input current start to sink into the device. A serial resistor
should be inserted in order to limit the input current mainly
during transient pulses. Recommended resistor value is
33kohms.
up function is not used, wake should be connected to GND to
avoid false wake up.
This pin is the MCU interface which reports the state of the
This pin controls the operation mode of the interface. If
If EN=0, the device is turned into sleep mode or low power
During sleep mode the device is still supplied from the
This pin is used to control an external switchable voltage
A wake-up event on the LIN bus line will switch the inhibit
This pin is a high voltage input used to wake up the device
Wake pin has special design structure and allows wake up
An internal filter is implemented, (50 s typical filtering
CAUTION : The Wake pin should not be left open. If wake
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