Datasheet

TJA1028 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2012. All rights reserved.
Product data sheet Rev. 4 — 25 July 2012 8 of 24
NXP Semiconductors
TJA1028
LIN transceiver with integrated voltage regulator
7.3.3 Reset (pin RSTN)
The output voltage on pin V
CC
is monitored continuously and a system reset signal is
generated (pin RSTN goes LOW) if an undervoltage event is detected (V
CC
< V
uvd
for
t
det(uv)(VCC)
). Pin RSTN will go HIGH again once the voltage on V
CC
exceeds the
undervoltage recovery threshold (V
uvr
) for t
rst
.
7.4 LIN transceiver
The transceiver is the interface between a LIN master/slave protocol controller and the
physical bus in a LIN network. It is primarily intended for in-vehicle sub-networks using
baud rates from 2.4 kBd up to 20 kBd and is LIN 2.0/LIN 2.1/SAE J2602 compliant.
7.5 Remote wake-up
A remote wake-up is triggered by a falling edge on pin LIN, followed by LIN remaining
LOW for at least t
wake(dom)LIN
, followed by a rising edge on pin LIN (see Figure 5).
The remote wake-up request is communicated to the microcontroller in Standby mode by
a continuous LOW level on pin RXD.
Note that t
wake(dom)LIN
is measured in Sleep and Standby modes, and in Normal mode if
TXD is HIGH.
7.6 Fail-safe features
7.6.1 General fail-safe features
The following general fail-safe features have been implemented:
• An internal pull-up towards V
CC
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 V
BAT
.
• A loss of power (pins V
BAT
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.
Fig 5. Remote wake-up behavior
015aaa088
LIN recessive
LIN dominant
Standby/Sleep mode Standby mode
V
BUSdom
V
BUSrec
ground
V
BAT
V
LIN
LOW
Sleep: floating/Standby: HIGH
RXD
t
wake(dom)LIN