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 7 of 24
NXP Semiconductors
TJA1028
LIN transceiver with integrated voltage regulator
7.2.5 Transition from Normal to Sleep or Standby mode
When EN is driven LOW in Normal mode, the TJA1028 disables the transmit path. The
mode select window opens t
msel(min)
after EN goes LOW, and remains open until t
msel(max)
after EN goes LOW (see Figure 4
).
The TXD pin is sampled in the mode select window. A transition to Standby mode is
triggered if TXD is HIGH, or to Sleep mode if TXD is LOW.
To avoid complicated timing in the application, EN and TXD can be pulled LOW at the
same time without having any effect on the LIN bus. In order to ensure that the remote
wake-up time (t
wake(dom)LIN
) is not reset on a transition to Sleep mode, TXD should be
pulled LOW at least t
d(EN-TXD)
after EN goes LOW. This is guaranteed by design.
The user must ensure the appropriate level is present on pin TXD while the mode select
window is open.
7.3 Power supplies
7.3.1 Battery (pin V
BAT
)
The TJA1028 contains a single supply pin, V
BAT
. An external diode is needed in series to
protect the device against negative voltages. The operating range is from 4.5 V to 28 V.
The TJA1028 can handle voltages up to 40 V (max). If the voltage on pin V
BAT
falls below
V
th(det)poff
, the TJA1028 switches to Off mode, shutting down the internal logic and the
voltage regulator and disabling the LIN transmitter. The TJA1028 exits Off mode as soon
as the voltage rises above V
th(det)pon
, provided the junction temperature is below T
th(rel)otp
.
7.3.2 Voltage regulator (pin V
CC
)
The TJA1028 contains a voltage regulator supplied via pin V
BAT
, which delivers up to
70 mA. It is designed to supply the microcontroller and its periphery via pin V
CC
.
TXD is sampled during the mode select window. The TJA1028 switches to Standby (TXD HIGH) or
Sleep (TXD LOW) mode after sampling.
Fig 4. Transition from Normal to Sleep/Standby mode
EN
TXD
operating
mode
mode select window
Normal with TXD
path blocked
Normal
Sleep or Standby depending on
TXD level in mode select window
t
msel(max)
t
msel(min)
015aaa087