AMIS-30523 Datasheet, PDF (26/35 Pages) ON Semiconductor – CAN Micro-Stepping Motor Driver

AMIS−30523
Watchdog Function
The watchdog function is enabled/disabled through
<WDEN> bit (See Table 15 SPI Control Registers address
00h). Once this bit has been set to “1” (watchdog enable), the
microcontroller needs to re−write this bit to clear an internal
timer before the watchdog timeout interval expires. In case
VBB
the timer is activated and WDEN is acknowledged too early
(before t_WDPR) or not within the interval (after t_WDTO), then
a reset of the microcontroller will occur through PORB/WD
pin. In addition, a warm/cold boot bit <WD> is available in
Table 17 for further processing when the external
microcontroller is alive again. See Figure 23.
VDD
t_PU
V_DDH
POR/WD pin
t_POR
t_DSPI
Enable WD
> t_WDPR and < t_WDTO
Acknowledge WD
t
t_WDTO
t
t
t_WDRD
t_POR
= t_WDPR or = t_WDTO
WD timer
t
Figure 23. Watchdog Timing Diagram
NOTE: t_DSPI is the time needed by the external microcontroller to shift−in the <WDEN> bit after a power−up.
The duration of the watchdog timeout interval is
programmable through the WDT[3:0] bits (See Table 14
SPI Control Registers address 00h). The timing is given in
Table 13 below.
http://onsemi.com
26