TH8065KDCAA MELEXIS [Melexis Microelectronic Systems], TH8065KDCAA Datasheet - Page 23

• Manufacturer Part Number: TH8065KDCAA
• Description: Voltage Regulator with LIN Transceiver and Watchdog
• Manufacturer: MELEXIS [Melexis Microelectronic Systems]

The reset output will be switched from high to low (watchdog reset), if the voltage on pin CWD reaches
V
The RESET pin generates a periodic signal with low pulse width of t
retrigger of WDI takes place.
Calculation of Watchdog time
Watchdog reset time:
Max. watchdog reset trigger time
With the valid charge and discharge currents of C
values for a defined watchdog trigger time and reset time possible:
Example:
If the watchdog has to be deactivated for e.g. firmware development, the pin CWD has to be directly
connected to GND. The reset signal is in this case only determined by the reset thresholds.
TH8065 – Datasheet
3901008065
CWDL
RESET
. The reset output stays at low level until the voltage at C
Within a timeframe of 10ms the MCU has to reset the watchdog to prevent a reset generation. The
complete watchdog period t
t
t
t
WDt
WD
WDt
C
CWD
WDI
t
V
V
V
WD
CWDM
WD
CWDH
CWDL
_
_
R
_
R
_
[ ]
R
[ ]
ms
=
R
ms
10
=
=
=
(
nF
=
V
(
V
0
C
CWDH
1 .
CWDH
WD
→
∗
[ ]
C
t
nF
WDt
WD
I
−
I
−
CWD
CWD
V
_
[ ]
V
nF
R
CWDL
CWDL
_
=
_
pd
10
pu
)
)
ms
WD_per
∗
∗
C
C
WD
and
WD
Voltage Regulator with LIN Transceiver and Watchdog
Figure 14 - Watchdog timing
= 11ms.
t
WD
_
R
Page 23 of 40
=
WD
1
ms
of the TH8065 is a simple calculation of the capacity
C
V
V
I
I
CWD_pu
CWD_pd
CWDH
CWDL
WD
t
WDt_R
WD
Watchdog capacity connected to pin CWD
Upper watchdog threshold
Lower watchdog threshold
CWD charge current
CWD discharge current
has reached the level of V
WDI = High or Low
t
WD_R
WD_R
t
WD_per
and a period of t
TH8065
CWDH
.
WD_per
May 2006
Rev 003
, if no