MLX80001 Datasheet, PDF (13/28 Pages) Melexis Microelectronic Systems – 4-channel Master LIN Transceiver

MLX80001
4-channel Master LIN Transceiver
3. Functional Description
3.1 TxDx Input pin - Logic command to transmit on LINx bus as follows:
TxD Polarity
• TxD = logic 1 (or floating) on this pin applies a recessive bus state (high bus voltage)
• TxD = logic 0 on this pin applies a bus dominant state depending on the transceiver mode state (low
bus voltage)
If the TxD pin is driven to a logic low state while the Mode 0,1 pins are in the 0,0 state or open, the
transceiver does not drive the LIN pin to the dominant state.
The pin contains an internal pull up to guarantee a recessive LIN behaviour in case of an open TxD pin. For
5V ECU supply systems an external pull up resistor is recommended.
TxD input thresholds are standard CMOS logic levels for 3.3V and 5V supply voltages.
3.2 RxDx Output pin - Logic data as sensed on the LINx bus
RxD polarity
• RxD = logic 1 on this pin indicates a bus recessive state (high bus voltage)
• RxD = logic 0 on this pin indicates a bus dominant state (low bus voltage)
The RxDx output is a low side open drain output. An external pull up resistor is required to realize the level
shift of an logic 1 level (high impedance output) to the Vcc_ECU voltage level.
Wake up source recognition
RxDx do not pass signals to the micro processor while in sleep mode until a valid wake up bus voltage level
is received or the Mode 0,1 pins are not 0,0 respectively. When the valid wake up bus signal awakens the
transceiver, the RxDx pin signalized an active low interrupt. This interrupt is active as long as no MODE pin
is switched to logic 1. After the MLX80001 enters an active mode, all valid bus signals will be sent out to the
RxD output.
The micro can detect the source of the wake up event and start the transmission only to the network caused
the wake up.
RxD time out feature
A dominant RxDx level longer than the specified time indicates a faulty blocked bus caused by a LIN node
itself or a short circuit to ground. The master pull up resistor of the LIN channel affected by the short will be
disconnected from the network in order to prevent thermal overload conditions or failure currents from the
battery without any intervention from the micro. The RxD timeout will be disabled with the next L->H
transition.
RxD Typical Load
Resistance: 2.7 kΩ
Capacitance: < 25 pF
(recommended pull up resistor)
(parasitic board capacitance)
MLX80001 – Datasheet
3901080001
Page 13 of 28
March 2007
Rev 001