TLE9221SX Datasheet, PDF (10/91 Pages) Infineon Technologies AG – FlexRay Transceiver

TLE9221SX
Functional Overview
4.2
Modes of Operation
The FlexRay bus driver TLE9221SX supports four different modes of operation:
• BD_Normal mode
• BD_ReceiveOnly mode
• BD_Standby mode
• BD_Sleep mode
Each mode has specific characteristics in terms of quiescent current, data transmission or failure diagnostic. To
enter the BD_Sleep mode, the TLE9221SX provides an intermediate mode, the so-called BD_GoToSleep
command.
Mode changes on the TLE9221SX are either triggered by:
• The Host Interface and a host command on the input pins EN and STBN.
• The Power Supply Interface and an undervoltage event on one of the two power supplies or the reference
supply uV_IO.
• The Wake-up Detector and wake-up events either on the FlexRay bus or on the local wake-up pin WAKE.
While all power supplies are turned off, the transceiver TLE9221SX is in BD_Off condition or also called “without
supply”.
In BD_Sleep mode and in BD_Standby mode the quiescent current consumption at all three supplies is tailored
to reach the minimum, and therefore only a limited set of the functions of the TLE9221SX is available. BD_Sleep
mode and BD_Standby mode are also called low power modes. Conversely the modes BD_Normal and
BD_ReceiveOnly are called non-low power modes.
4.3
Behavior of Unconnected Digital Input Pins
The integrated pull-up and pull-down resistors at the digital input pins force the TLE9221SX into a secure, fail safe
behavior if the input pins are not connected and floating (see Table 2 for details).
If the TxEN pin or the BGE pin is not connected in BD_Normal mode, the Transmitter is disabled. If the TxD input
pin is open in BD_Normal mode and the Transmitter is active, the transceiver TLE9221SX drives a “Data_0” signal
to the bus.
If the mode control input pins of the Host Interface are not connected, the pull-down resistors on the EN pin and
on the STBN pin set the TLE9221SX by default to BD_Standby mode.
Table 2 Logical inputs when unconnected
Input Signal
TxD¹⁾
TxEN¹⁾
STBN
Default State
“low”
“high”
“low”
Comment
pull-down to GND
pull-up to uV_IO
pull-down to GND
EN
BGE¹⁾
“low”
“low”
pull-down to GND
pull-down to GND
1) In the low power modes, BD_Sleep and BD_Standby, the inputs TxD, TxEN and BGE are blocked by the internal logic. To
optimize the total quiescent current consumption, the pull-up and pull-down structures are disabled in BD_Sleep mode.
The Power Supply Interface detects missing supply voltages or a missing reference supply. The Central State
Machine sets the TLE9221SX into a fail safe mode when a supply is not available (details see Chapter 8.3).
Data Sheet
10
Rev. 1.10, 2013-07-15