TJA1028
NXP Semiconductors
LIN transceiver with integrated voltage regulator
7.4 Remote wake-up
A remote wake-up is triggered by a falling edge on pin LIN, followed by LIN remaining
LOW for at least twake(busdom)min, followed by a rising edge on pin LIN (see Figure 5).
LIN recessive
V
BAT
0.6V
BAT
V
LIN
0.4V
t
wake(busdom)min
BAT
LIN dominant
ground
Standby/Sleep mode
Standby mode
LOW
Sleep: floating/Standby: HIGH
RXD
015aaa088
Fig 5. Remote wake-up behavior
The remote wake-up request is communicated to the microcontroller in Standby mode by
a continuous LOW level on pin RXD.
Note that twake(busdom)min is measured in Sleep and Standby modes, and in Normal mode if
TXD is HIGH.
7.5 Fail-safe features
7.5.1 General fail-safe features
The following general fail-safe features have been implemented:
• An internal pull-up towards VCC on pin TXD guarantees a recessive bus level if the pin
is left floating by a bad solder joint or floating microcontroller port pin.
• The current in the transmitter output stage is limited in order to protect the transmitter
against short circuits to pin VBAT
.
• A loss of power (pins VBAT and GND) has no impact on the bus line or on the
microcontroller. There will be no reverse currents from the bus.
• The LIN transmitter is automatically disabled when either EN or RSTN is LOW.
• After a transition to Normal mode, the LIN transmitter is only enabled if a recessive
level is present on pin TXD.
7.5.2 TXD dominant time-out function
A TXD dominant time-out timer circuit prevents the bus line being driven to a permanent
dominant state (blocking all network communications) if TXD is forced permanently LOW
by a hardware or software application failure. The timer is triggered by a negative edge on
the TXD pin. If the pin remains LOW for longer than the TXD dominant time-out time
(tto(dom)TXD), the transmitter is disabled, driving the bus line to a recessive state. The timer
is reset by a positive edge on TXD.
TJA1028
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2011. All rights reserved.
Product data sheet
Rev. 2 — 25 February 2011
8 of 24
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