tja1021 NXP Semiconductors, tja1021 Datasheet - Page 7

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

NXP Semiconductors
TJA1021_3
Product data sheet
7.4 Normal mode
7.5 Wake-up
7.6 Remote and local wake-up
7.7 Wake-up via mode transition
In normal mode the TJA1021 is able to transmit and receive data via the LIN bus line. The
receiver detects the data stream at the LIN bus input pin and transfers it via pin RXD to the
microcontroller (see
the bus. The receiver has a supply-voltage related threshold with hysteresis and an
integrated filter to suppress bus line noise. The transmit data stream of the protocol
controller at the TXD input is converted by the transmitter into a bus signal with optimized
slew rate and wave shaping to minimize EME. The LIN bus output pin is pulled HIGH via
an internal slave termination resistor. For a master application an external resistor in
series with a diode should be connected between pin INH or V
on the other side (see
Being in sleep, standby or power-up mode, the TJA1021 enters normal mode whenever a
HIGH level on pin SLP_N is maintained for a time of at least t
The TJA1021 switches to sleep mode in case of a LOW-level on pin SLP_N, maintained
for a time of at least t
When V
power-on mode. Though the TJA1021 is powered-up and INH is HIGH, both the
transmitter and receiver are still inactive. If SLP_N = 1 for t > t
normal mode.
There are three ways to wake-up a TJA1021 which is in sleep mode:
A falling edge at pin LIN followed by a LOW level maintained for a certain time period
(t
wake-up. It should be noted that the time period t
mode while TXD is HIGH, or in sleep mode irrespective of the status of pin TXD.
A falling edge at pin WAKE_N followed by a LOW level maintained for a certain time
period (t
pull-up towards pin V
unused pin WAKE_N to pin V
After a local or remote wake-up, pin INH is activated (it goes HIGH) and the internal slave
termination resistor is switched on. The wake-up request is indicated by a LOW active
wake-up request signal on pin RXD to interrupt the microcontroller.
It is also possible to set pin INH HIGH with a mode transition towards normal mode via pin
SLP_N. This is useful for applications with a continuously powered microcontroller.
1. Remote wake-up via a dominant bus state of at least t
2. Local wake-up via a negative edge at pin WAKE_N
3. Mode change (pin SLP_N is HIGH) from sleep mode to normal mode
wake(dom)LIN
BAT
wake(dom)WAKE_N
exceeds the power-on-reset threshold voltage V
) and a rising edge at pin LIN respectively (see
Figure
BAT
gotosleep
Rev. 03 — 8 October 2007
Figure
) results in a local wake-up. The pin WAKE_N provides an internal
. In order to prevent EMI issues, it is recommended to connect an
1): HIGH at a recessive level and LOW at a dominant level on
.
BAT
6).
.
wake(dom)LIN
LIN 2.0/SAE J2602 transceiver
wake(dom)LIN
th(POR)H
Figure
is measured either in normal
gotonorm
gotonorm
BAT
on one side and pin LIN
4) results in a remote
, the TJA1021 enters
, the TJA1021 enters
.
© NXP B.V. 2007. All rights reserved.
TJA1021
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