TLE7368_10 Datasheet, PDF (31/41 Pages) Infineon Technologies AG – Next Generation Micro Controller Supply

TLE7368
Detailed Internal Circuits Description
5.9
Monitoring Circuit
The monitoring block within the TLE7368 detects an undervoltage at the stand-by regulator output and is able to
distinguish between two different undervoltage situations. When the stand-by output gets back into regulation after
an undervoltage event, the timing on the MON_STBY output signal indicates the kind of undervoltage scenario
which has happened before. The behavior of the monitoring block is also described in Figure 6 and Figure 7
below.
In case of an undervoltage at the stand-by regulator with the 5 V regulator LDO1 in regulation (which means that
RO_1 = HIGH) the monitoring circuit has basically a power fail functionality which means that the MON_STBY
output will be LOW just as long as the undervoltage at the stand-by output occurs. As soon as Q_STBY is coming
back into regulation MON_STBY turns high again.
When the 5 V regulator is out of regulation (RO_1 = LOW), e.g. in case of EN_uC = EN_IGN = LOW, the
MON_STBY will turn LOW again if an undervoltage event happens at Q_STBY. The difference to the scenario
described above is now that when Q_STBY gets back into regulation the toggling of the MON_STBY output to
HIGH is coupled with the 5 V Reset line, RO_1, turning HIGH. In detail, the MON_STBY line turns high delayed
by t_{MON_STBY} after the Reset line RO_1 had gone high.
V_{Q_STBY} < V_{MON, Q_STBY, de}
and
RO_1 = High
MON = High
Monitor timing
= don’t care
V_{Q_STBY} < V_{MON, Q_STBY, de}
and
RO_1 = Low
V_{Q_STBY} > V_{MON, Q_STBY, in}
and
RO_1 = High
MON = Low
V_{Q_STBY} > V_{MON, Q_STBY, in}
and
RO_1 = High
MON = Low
Monitor timing
= no delay ^*)
V_{Q_STBY} < V_{MON, Q_STBY, de}
and
RO_1 = Low
Monitor timing
= delay^**)
*) _{power fail functionionality}
**) _{power on reset functionality}
Figure 6 Stand by Monitor State Diagram
V_{Q_STBY} > V_{MON, Q_STBY, in}
and
RO_1 = Low
Data Sheet
31
Rev. 2.1, 2010-11-22