TLE9221SX Datasheet, PDF (35/91 Pages) Infineon Technologies AG – FlexRay Transceiver

TLE9221SX
Power Supply Interface
STBN
t
EN
uV_BAT
ERRN
BD_Normal
undervoltage detection timer
dBDUVV_{BAT_BLK}
dBDUVV_BAT
set undervoltage flag
set undervoltage bit
set error bit
dReactionTime_ERRN
BD_Sleep
undervoltage release timer
t
BD_Normal
dBDRV_BAT
clear undervoltage flag
t
t
Figure 25 Example of setting the undervoltage flag
Besides the undervoltage detection timer, each supply is also equipped with an undervoltage recovery timer. The
undervoltage recovery timer starts when the external power supply recovers. When the undervoltage recovery
timer expires, the undervoltage flag gets reset (see Figure 25). If the external power supply recovers only
temporarily and the supply line falls back to the undervoltage situation while the undervoltage recovery timer is still
running, the undervoltage flag remains set. Clearing the undervoltage flag allows the transceiver TLE9221SX to
return from low power mode to the previous operational mode selected by the host command (see Chapter 9.4
and Table 15).
Note: Undervoltage bits are set by an undervoltage event. Undervoltage bits are stored in the SIR and also
indicated at the ERRN output.
Undervoltage flags are set by the undervoltage detection timer. Undervoltage flags are not visible in the SIR
and they are not indicated at the ERRN output. Undervoltage flags are only used to change the mode of
operation after the undervoltage detection timer has expired!
8.3.2
Undervoltage Event at uV_BAT
The FlexRay transceiver TLE9221SX considers a voltage fluctuation on the power supply uV_BAT, which falls below
the detection threshold uBDUVV_BAT and exceeds the blanking time dBDUV_{BAT_BLK}, as an undervoltage event.
Voltage fluctuations on uV_BAT shorter than dBDUV_{BAT_BLK} are ignored and not recognized by the Power Supply
Interface. To indicate the undervoltage event on the supply voltage uV_BAT, the uV_BAT undervoltage bit (bit 8) and
the error bit (bit 11) are set (see Figure 26). After the uV_BAT undervoltage detection timer dBDUVV_BAT expires, the
uV_BAT undervoltage flag is set and the mode of operation changes to BD_Sleep mode.
The Host Interface and the Communication Controller Interface are active while the dBDUVV_BAT undervoltage
detection timer is running and the reference supply uV_IO is present. When the dBDUVV_BAT undervoltage detection
timer expires and the uV_BAT undervoltage flag is set, the Host Interface and the Communication Controller
Data Sheet
35
Rev. 1.10, 2013-07-15