MLX80004 Datasheet, PDF (22/38 Pages) Melexis Microelectronic Systems – Enhanced Universal Dual/Quad LIN Transceiver

MLX80002/MLX80004
Enhanced Universal Dual/Quad LIN Transceiver
Datasheet
9. Fail-safe Features
9.1. Loss of battery
If the ECU is disconnected from the battery, the bus pin is in high impedance state. There is no impact to the bus traffic
and to the ECU itself. Reverse current is limited to < 20µA
9.2. Loss of Ground
In case of an interrupted ECU ground connection there is no influence to the bus lines. The current from the ECU to the
LINx pins is limited by the weak pull up current of the pin LINx, the integrated master termination (DIS_MAS = GND) as
well as the integrated slave termination (DIS_MAS = V_s) is disconnected in order to fulfill the SAE J2602 requirements
for the loss of ground current (<100µA @12V).
9.3. Short circuit to battery
The transmitter output currents are limited to the specified value in case of short circuit to battery in order to prevent
high current densities and thermal hot spots in the LIN drivers. In dependency of the ambient temperature as well as
the battery voltage the junction temperature can exceed the specified value and a thermal overload condition occurs
(see chapter 4.5)
9.4. Ground shift and short circuit to ground
If the LIN bus wiring is shorted to negative shifted ground levels, there is no current flow from the ECU ground to the
LIN bus and no distortion of the bus traffic occurs.
A LIN bus short to ground condition can cause an undesired current flow. The MLX80004/MLX80002 offers different
opportunities to handle the LIN short to ground, see chapter 8.7.
9.5. Thermal overload
The MLX80004 and the MLX80002 is protected against thermal overloads. If the chip junction temperature exceeds
the specified value, all transmitters are disabled and the master termination is switched off in order to reduce the
power consumption. The receiver is still working during the thermal shutdown state. The pins RxDx indicate the
voltage level from the LINx pins also if the circuit is in thermal shut down. The circuit returns automatically to the
normal mode after thermal recovery.
9.6. Undervoltage lock out
If the battery supply voltage is missing or decreased under the specified value (V_{S_UV}), all transmitters are disabled to
prevent undefined bus traffic.
While in sleep mode, the MLX80004/2 enters the standby mode if Vs drops below the internal power on reset
threshold (V_INH = V_s).
9.7. Open Circuit protection
 The pins TxDx provide a weak pull down. The transmitter cannot be enabled.
 The pins MODE0/MODE1 provide a weak pull down to prevent undefined active mode transitions.
 If the battery supply voltage is disconnected, the pins RxDx are floating
 The pin WAKE provides a weak pull up current towards supply voltage Vs to prevent local wake-up requests.
 The pin DIS_MAS provides a pull down current of 50uA.
Revision 021 – Sept 2016
Page 22 of 38