TLE7250X Datasheet, PDF (29/34 Pages) Infineon Technologies AG – High Speed CAN-Transceiver

TLE7250XLE
TLE7250XSJ
Application Information
8.3.1 Mode Change while the TxD Signal is “low”
The example in Figure 14 shows a mode change to normal-operating mode while the TxD input is logical “low”.
The HS CAN signal is “recessive”, assuming all other HS CAN bus subscribers are also sending a “recessive” bus
signal.
While the transceiver TLE7250X is in receive-only mode the transmitter is turned off. The TLE7250X drives no
signal to the HS CAN bus. The normal-mode receiver is active in receive-only mode and the RxD indicates the
“recessive” signal on the HS CAN bus with a logical “high” output signal.
Changing the RM to logical “low” turns the mode of operation to normal-operating mode, while the TxD input
remains logical “low”. The transmitter remains disabled until the mode change is completed. The normal-mode
receiver remains active also during the mode change. In normal-operating mode the transmitter becomes active
and the logical “low” signal on the TxD input drives a “dominant” signal to the HS CAN bus. The “dominant” bus
signal is indicated on the RxD output by a logical “low” signal.
Changing the RM pin back to logical “high”, disables the transmitter. The normal-mode receiver and the RxD
output remain active and the “recessive” bus signal is indicated on the RxD output by a logical “high” signal.
Note: The signals on the HS CAN bus are “recessive”, the “dominant” signal is
generated by the TxD input signal
RM
t = t_Mode
t = t_Mode
t
TxD
t
V_DIFF
t
RxD
receive-only transition normal-operating transition
t
receive-only
normal-mode receiver and RxD output active
TxD input and transmitter
blocked
TxD input and transmitter
active
TxD input and transmitter blocked
Figure 14 Example for a mode change while the TxD is “low”
Data Sheet
29
Rev. 1.0, 2015-08-12