TLE9221SX Datasheet, PDF (34/91 Pages) Infineon Technologies AG – FlexRay Transceiver

TLE9221SX
Power Supply Interface
uBDPDV_BAT
+
uV_BAT
-
uBDPDV_CC
+
&
BD_Off
uV_CC
-
Figure 24 Logic diagram of BD_Off detection
Note: When the transceiver TLE9221SX is in BD_Off state, the Central State Machine is powered down. All
registers in TLE9221SX are built of volatile memory and therefore, all status, diagnostic, and failure
information is reset.
8.3
Undervoltage Events
8.3.1 Undervoltage Flags and Undervoltage Bits
Detected undervoltage events are stored using a dedicated undervoltage bit and they are visible in the SIR. Along
with the undervoltage bit a summary bit, the error bit (bit 11), is set. The error bit is indicated at the ERRN output,
depending on the selected operation mode (see Table 9 and the example in Figure 25).
The TLE9221SX provides three bits in the SIR to signal undervoltage events:
• uV_BAT undervoltage bit (bit 8)
• uV_CC undervoltage bit (bit 9)
• uV_IO undervoltage bit (bit 10)
Undervoltage bits are used to store the information for further use. Therefore undervoltage bits get cleared only
by a power-down or by clearing the SIR (see Chapter 6.2.3).
In comparison to the undervoltage bits, undervoltage flags are not latched and they are only used to trigger the
changes of the operation mode. Undervoltage flags are not visible externally.
An undervoltage event on any supply line directly sets the dedicated undervoltage bit and also the error bit. The
undervoltage flags are set by internal timers. An internal undervoltage detection timer is available for every supply,
uV_BAT, uV_CC and uV_IO. While setting the undervoltage bit, the appropriate undervoltage detection timer is also
triggered. When the undervoltage detection timer expires, while the undervoltage event is still present, the
undervoltage flag is set (see Figure 25).
In case the undervoltage situation gets cleared while the undervoltage detection timer is running, the TLE9221SX
does not set the undervoltage flag. According to the mode change table, an active undervoltage flag changes the
mode of operation to low power mode (see Chapter 9.3 and Table 14).
Data Sheet
34
Rev. 1.10, 2013-07-15