ATA6824_08 ATMEL [ATMEL Corporation], ATA6824_08 Datasheet - Page 8

• Manufacturer Part Number: ATA6824_08
• Description: High Temperature H-bridge Motor Driver
• Manufacturer: ATMEL [ATMEL Corporation]

5.3.1
8
ATA6824
Timing Sequence
For example, with an external resistor R
of the watchdog.
T
The times t
After ramp-up of the battery voltage (power-on reset), the V
reset output, /RESET, stays low for the time t
initial lead time t
edge on WD to start its normal window watchdog sequence. If no rising edge is detected, the
watchdog will reset the microcontroller for t
Times t
receiving a reset from the watchdog, the triggering signal from the microcontroller must hit the
timeframe of t
Figure 5-3.
If triggering fails, /RESET will be pulled to ground for a shortened reset time of typically 2 ms.
The watchdog start sequence is similar to the power-on reset.
The internal oscillator is trimmed to a tolerance of < ±10%. This means that t
vary by ±10%. The following calculation shows the worst case calculation of the watchdog
period T
t
t
T
T
T
Figure 5-3 on page 8
external resistor R
A reset will be active for V
1min
2min
OSC
wdmax
wdmin
wd
= 16.42 ms ±3.15 ms (±19.1%)
= 0.90
= 0.90
= 12.32 µs, t
= t
= t
1
wd
(close window) and t
1max
1min
which the microcontroller has to provide.
res
+ t
= 13.28 ms
2
t
t
= 68 ms and t
1
2
T
= 9.61 ms. The trigger event will restart the watchdog sequence.
WD
= 10.87 ms, t
= 8.65ms, t
2min
d
1
OSC
(typically 68 ms for setups in the controller) the watchdog waits for a rising
versus R
= 12.1 ms, t
= 10.87 ms + 8.65 ms = 19.52 ms
.
shows the typical watchdog period T
60
40
30
20
50
10
0
10
CC
2max
d
WD
< V
1max
= 68 ms are fixed values with a tolerance of 10%.
2
20
2
(open window) form the window watchdog sequence. To avoid
= 1.10
tHRESx
= 9.61 ms, T
= 1.10
30
; the level V
WD
t
40
2
res
t
= 10.57 ms
= 33 k ±1% we get the following typical parameters
1
= 13.28 ms
WD
res
and wait t
50
RWD (k )
(typically 68 ms), then switches to high. For an
= 16.88 ms ±10%
tHRESx
60
max
d
is realized with a hysteresis (HYS
for the rising edge on WD.
70
min
WD
CC
80
depending on the value of the
regulator is switched on. The
90
typ
100
1
and t
4931E–AUTO–01/08
2
can also
RESth
).