ATA6823 ATMEL Corporation, ATA6823 Datasheet - Page 10

• Manufacturer Part Number: ATA6823
• Description: H-bridge Motor Driver
• Manufacturer: ATMEL Corporation

5.6
10
LIN Transceiver
ATA6823 [Preliminary]
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
resistor R
A reset will be active for V
A bi-directional bus interface is implemented for data transfer between the LIN bus and the local
LIN protocol controller.
The transceiver consists of a low side driver (1.2V at 40 mA) with slew rate control, wave shap-
ing, current limitation, and a high-voltage comparator followed by a debouncing unit in the
receiver.
1min
2min
wdmax
wdmin
wd
= 16.42 ms ±3.15 ms (±19.1%)
= 0.90
= 0.90
= t
= t
1
wd
(close window) and t
1max
1min
OSC
which the microcontroller has to provide.
above shows the typical watchdog period T
.
+ t
= 13.28 ms
2
t
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
(typically 68 ms for setups in the controller) the watchdog waits for a rising
versus R
= 10.87 ms + 8.65 ms = 19.52 ms
60
40
30
20
50
10
0
10
CC
2max
WD
< V
1max
2
20
(open window) form the window watchdog sequence. To avoid
= 1.10
tHRESx
= 1.10
30
; the level V
t
40
2
res
t
= 10.57 ms
1
= 13.28 ms
res
and wait t
50
RWD (k )
(typically 68 ms), then switches to high. For an
tHRESx
60
WD
max
d
is realized with a hysteresis (HYS
for the rising edge on WD.
depending on the value of the external
70
min
CC
80
regulator is switched on. The
90
typ
100
1
and t
4856E–AUTO–07/07
2
can also
RESth
).