TLE6368_06 Datasheet, PDF (14/59 Pages) Infineon Technologies AG – Multi-Voltage Processor Power Supply

TLE 6368 / SONIC
t_CW=t_CW
t_OW=t_CW
definition closed window open window
t_SR = t_OW/2
(not the same scale)
reset delay time without trigger
t_WDR = t_RES
(not the same scale)
definition
reset start delay time after window
watchdog timeout
reset duration time after window
watchdog time-out
t_ECW
f_OSC=f_OSCmax t _{EOW, w.c.}= ( t_CW+t_OW )(1-∆)
worst cases
f_OSC=f_OSCmin t _{ECW, w.c.}= t_CW (1+∆)
t _EOW = end of open window
t _OWmin
Minimum open window time: t _OWmin= t_OW - ∆ * ( t _OW + 2* t _CW )
Example with:
t_CW=128ms
∆=25% (oscillator deviation)
t_{ECW, w.c.} = 128(1.25) = 160ms
t_{EOW, w.c} = (128+128)(0.75) = 192ms
t_owmin = 32ms
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.
Data Sheet
14
Rev. 2.2, 2006-12-01