tja1021 NXP Semiconductors, tja1021 Datasheet - Page 6

• Manufacturer Part Number: tja1021
• Description: Tja1021 Lin 2.0/sae J2602 Transceiver
• Manufacturer: NXP Semiconductors

NXP Semiconductors
[4]
[5]
TJA1021_3
Product data sheet
Normal mode is entered after a positive edge on SLP_N. As long as TXD is LOW, the transmitter is off. In the event of a short-circuit to
ground on pin TXD, the transmitter will be disabled.
Power-on mode is entered after switching on V
7.2 Sleep mode
7.3 Standby mode
This mode is the most power-saving mode of the TJA1021. Despite its extreme low
current consumption, the TJA1021 can still be woken up remotely via pin LIN, or woken up
locally via pin WAKE_N, or activated directly via pin SLP_N. Filters at the inputs of the
receiver (LIN), of pin WAKE_N and of pin SLP_N prevent unwanted wake-up events due
to automotive transients or EMI. All wake-up events have to be maintained for a certain
time period (t
Sleep mode is initiated by a falling edge on pin SLP_N in normal mode. To enter sleep
mode successfully (INH becomes floating), the sleep command (pin SLP_N = LOW) must
be maintained for at least t
In sleep mode the internal slave termination between pins LIN and V
minimize the power dissipation in the event that pin LIN is short-circuited to ground. Only a
weak pull-up between pins LIN and V
Sleep mode can be activated independently from the actual level on pin LIN, pin TXD or
pin WAKE_N. So it is guaranteed that the lowest power consumption is achievable even in
case of a continuous dominant level on pin LIN or a continuous LOW on pin WAKE_N.
When V
mode.
Standby mode is entered automatically whenever a local or remote wake-up occurs while
the TJA1021 is in sleep mode. These wake-up events activate pin INH and enable the
slave termination resistor at the pin LIN. As a result of the HIGH condition on pin INH the
voltage regulator and the microcontroller can be activated.
Standby mode is signalled by a LOW-level on pin RXD which can be used as an interrupt
for the microcontroller.
In standby mode (pin SLP_N is still LOW), the condition of pin TXD (weak pull-down or
strong pull-down) indicates the wake-up source: weak pull-down for a remote wake-up
request and strong pull-down for a local wake-up request.
Setting pin SLP_N HIGH during standby mode results in the following events:
•
•
•
An immediate reset of the wake-up source flag; thus releasing the possible strong
pull-down at pin TXD before the actual mode change (after t
A change into normal mode if the HIGH level on pin SLP_N has been maintained for a
certain time period (t
An immediate reset of the wake-up request signal on pin RXD
BAT
drops below the power-on-reset threshold V
wake(dom)LIN
BAT
.
Rev. 03 — 8 October 2007
, t
gotonorm
wake(dom)WAKE_N
gotosleep
)
.
BAT
is present.
and t
gotonorm
).
th(POR)L
LIN 2.0/SAE J2602 transceiver
, the TJA1021 enters sleep
gotonorm
BAT
© NXP B.V. 2007. All rights reserved.
TJA1021
) is performed
is disabled to
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