TLE7251V_15 Datasheet, PDF (31/36 Pages) Infineon Technologies AG – High Speed CAN-Transceiver with Bus Wake-up

8.3.2
TLE7251VLE
TLE7251VSJ
Application Information
Mode Changes from Stand-by Mode to Normal-operating Mode
8.3.2.1 Mode Change while the TxD Signal is “low”
The example in Figure 16 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 TLE7251V is in stand-by mode, the transmitter and the normal-mode receiver are turned off.
In stand-by mode the low-power receiver is active. The TLE7251V drives no signal to the HS CAN bus, the RxD
output is connected to the low-power receiver and follows only the HS_CAN bus signals when its pulse width
exceeds the CAN activity filter time t_Filter. Changing the STB to logical “low” turns the mode of operation to normal-
operating mode, while the TxD input signal remains logical “low”. The transmitter and the normal-mode receiver
remain disabled until the mode transition is completed. During the mode transition the RxD output is blocked and
set to logical “high”. In normal-operating mode the transmitter and the normal-mode receiver are active. The “low”
signal on the TxD input drives a “dominant” signal to the HS CAN bus and the RxD output becomes logical “low”
following the “dominant” signal on the HS CAN bus.
Changing the STB pin back to logical “high”, disables the transmitter and normal-mode receiver again. The RxD
output pin is blocked and set to logical “high” with the start of the mode transition. The TxD input and the transmitter
are blocked and the HS CAN bus becomes “recessive”.
Note: The signals on the HS CAN bus are “recessive”, the “dominant” signal is
generated by the TxD input signal
t = t_Mode
STB
t = t_Mode
t
TxD
t
V_Diff
t
RxD
stand-by mode transition normal-operating transition
t
stand-by mode
low-power receiver RxD output
active
blocked
normal-mode receiver
active
RxD output
blocked
low-power receiver active
TxD input and transmitter blocked
TxD input and transmitter
active
TxD input and transmitter blocked
Figure 16 Mode change from stand-by mode to normal-operating mode
Data Sheet
31
Rev. 1.0, 2015-09-10