Datasheet

TJA1024 All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2015. All rights reserved.
Product data sheet Rev. 1 — 12 February 2015 10 of 25
NXP Semiconductors
TJA1024
Quad LIN 2.2A/SAE J2602 transceiver
If the voltage on pin V
BATx
drops below the LOW-level power-on reset threshold, V
th(POR)L
,
the associated transceivers switch to Reset mode (i.e. the output drivers are disabled and
the inputs are ignored). When the voltage on V
BATx
rises again above V
th(POR)H
, the
transceivers will switch to Sleep mode.
7.6 Fail-safe features
Pin TXDx is pulled down to ground in order to force a predefined level on the transmit data
input if the pin is disconnected.
Pin SLPx_N is pulled down to ground to ensure that the transceiver is forced to Sleep x
mode if SLPx_N is disconnected.
Pins RXD1 and RXD2 are set floating if V
BAT1
is disconnected. Pins RXD3 and RXD4 are
set floating if V
BAT2
is disconnected.
The current in the transmitter output stage is limited to protect the transmitter against short
circuits to pins V
BATx
or GNDx.
A loss of power (pins V
BATx
and GNDx) has no impact on the bus lines or on the
microcontroller. No reverse currents flow from the bus lines into the LINx pins. The current
path from V
BATx
to LINx via the integrated LIN slave termination resistors remains. The
TJA1024 can be disconnected from the power supply without influencing the LIN buses.
The output drivers on pins LIN1, LIN2, LIN3 and LIN4 are protected against
overtemperature conditions. If the junction temperature at one of the transceiver blocks
exceeds the shutdown junction temperature, T
j(sd)
, the thermal protection circuit disables
the relevant output drivers (LIN1/LIN2 or LIN3/LIN4). The drivers are enabled again when
the junction temperature falls below T
j(sd)
and pin TXDx is HIGH.
The initial TXD dominant check prevents the bus being driven to a permanent dominant
state (blocking all network communications) if pin TXDx is forced permanently LOW by a
hardware and/or software application failure. The input level on TXDx is checked after a
transition to Normal mode. If TXDx is LOW, the transmit path remains disabled and is only
enabled when TXDx goes HIGH.
Once the transmitter has been enabled, a TXD dominant time-out timer is started every
time pin TXDx goes LOW. If the LOW state on pin TXDx persists for longer than the TXD
dominant time-out time (t
to(dom)TXD
), the transmitter is disabled, releasing the bus line to
recessive state. The TXD dominant time-out timer is reset when pin TXDx goes HIGH.