Rainbow Electronics ATA6631 - Manual (Page 12)

12
9165A–AUTO–11/09
ATA6629/ATA6631
A wake-up event from either Silent or Sleep Mode will be signalled to the microcontroller using
the two pins RXD and TXD. The coding is shown in
Table 4-3 .
A wake-up event will lead the IC to the Fail-safe Mode.
4.6 Unpowered Mode
If you connect battery voltage to the application circuit, the voltage at the VS pin increases
according to the block capacitor (see
Figure 6-1 on page 14 ). After VS is higher than the VS
undervoltage threshold VS
th
, the IC mode changes from Unpowered Mode to Fail-safe Mode.
The VCC output voltage reaches its nominal value after t
VCC
. This time, t
VCC
, depends on the
VCC capacitor and the load.
The NRES is low for the reset time delay t
reset
. During this time, t
reset
, no mode change is
possible.
IF VS drops below VS
th
, then the IC switches to Unpowered Mode. The behaviour of VCC,
NRES and LIN is shown in Figure 4-8 .
Figure 4-8. VCC versus VS for the VCC = 3.3V Regulator
Table 4-3. Signalling Fail-safe Sources
Fail-safe Sources TXD RXD
LIN wake up (pin LIN) Low Low
VS
th
(battery) undervoltage detection High Low
0 .0
0 .5
1.0
1.5
2 .0
2 .5
3 .0
3 .5
4 .0
4 .5
5.0
5.5
6 .0
0 .0 0 .5 1.0 1.5 2 .0 2 .5 3 .0 3 .5 4 .0 4 .5 5.0 5.5 6 .0
VS in V
V in V
VCC
LIN
NRES
VS
Regulator drop voltage V
D