TLE6368 Infineon Technologies, TLE6368 Datasheet - Page 14

• Manufacturer Part Number: TLE6368
• Description: Multi-Voltage Processor Power Supply
• Manufacturer: Infineon Technologies

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Data Sheet, Rev. 1.32
Figure 6 Window watchdog timing definition
Figure 6 shows some guidelines for designing the watchdog trigger timing taking the
oscillator deviation of different devices into account. Of importance (w.c.) is the
maximum of the closed window and the minimum of the open window in which the
trigger has to occur.
The length of the OW and CW can be modified by SPI command. If a change of the
window length is desired during the Watchdog function is operating please send the SPI
command with the new timing with a ’Watchdog trigger Bit’ D15=1.In this case the next
CW will directly start with the new length.
A minimum time gap of > 1/48 of the actual OW/CW time between a ’Watchdog disable’
and ’Watchdog enable’ SPI-command should be maintained. This allows the internal
Watchdog counters to be resetted. Thus after the enable command the Watchdog will
start properly with a full CW of the adjusted length.
worst cases
definition
definition
f
f
OSC
OSC
=f
=f
OSCmax
OSCmin
Minimum open window time:
t
t
EOW, w.c.
closed window
ECW, w.c.
t
CW
=t
= ( t
= t
CW
CW
CW
(1+ )
+t
t
ECW
OW
)(1- )
open window
t
OWmin
t
OW
=t
CW
t
t
OWmin
EOW
reset start delay time after window
= end of open window
= t
reset delay time without trigger
OW
(not the same scale)
-
14
watchdog timeout
* ( t
t
SR
= t
OW
OW
+ 2* t
/2
CW
)
Example with:
t
t
t
t
CW
ECW, w.c.
EOW, w.c
owmin
=25% (oscillator deviation)
=128ms
reset duration time after window
TLE 6368 / SONIC
(not the same scale)
= 128(1.25) = 160ms
= (128+128)(0.75) = 192ms
= 32ms
watchdog time-out
t
WDR
= t
RES
2004-10-15