BTS 5590G Infineon Technologies, BTS 5590G Datasheet - Page 33

• Manufacturer Part Number: BTS 5590G
• Manufacturer: Infineon Technologies

Specifications of BTS 5590G

• Packages: PG-DSO-36
• Channels: 5.0
• Channel Mix: 2*25mohm+1*40mohm+2*100mohm
• Led Mode: Yes
• Cranking Mode: No
• Pwm Engine Integrated: No

9
The SPOC - BTS5590G provides a sophisticated watchdog function with trigger state machine to build a secure
limp home signalling. The fail safe block is supplied via
watchdog overrun independently of
ignition signal of the car.
As soon as the limp home function is enabled, the watchdog is started and must be served. The timing can be
adjusted in a wide range by choosing the appropriate capacitor. For calculation of the watchdog timing, please
refer to
The watchdog is served via a trigger state machine, which starts at a defined state when limp home has been
enabled. As a result, the state machine might also be reset to this startup state due to a voltage drop at pin LHEN.
A watchdog overrun causes the LHO pin to turn from tri-state to a high signal. This signal can be utilized to switch
on dedicated channels by connecting LHO to the appropriate input pins and it is suitable to turn other hardware of
the system into limp home mode as well. Once the watchdog has been overrun, it can be reset by a low signal at
pin LHEN only. There is no software reset mechanism implemented for this function to make sure, a faulty software
can not turn off the limp home mode.
The status of the watchdog as well as the trigger state machine can be read via SPI. As a result, the micro
controller can perform a watchdog check via SPI.
Please see following
Figure 19
9.1
The watchdog function is built as analog trigger watchdog with external capacitor C
at pin LHEN enables the watchdog. A constant current loads the external capacitor, so the voltage rise is linear.
When the watchdog is served, the capacitor is discharged to level V
following figure for details.
Figure 20
Data Sheet
Section
Limp Home
Block Diagram: Limp Home
Watchdog
Watchdog Behavior
9.1.
V
trigger
V
LHEN
LHD(O)
LHD(R)
V
V
Figure 19
LHD
LHO
LHEN
WDTR
WDC
trigger state machine
LHEN
LHO
WDL
WDC += 1
sub
for details.
WDTR == WDC
V
DD
OR
. There is an enable pin LHEN available which is usually connected to the
OR
&
WDC += 1
&
33
supply
power
V
BB
VBB
V
I
I
LHD(C)
LHD(D)
LHD(O)
and provides an output signal at pin LHO in case of
V
LHD(R)
LHD(R)
GND
and the cycle starts again. Please see
LHO
LHD
C
WD
WD
LimpHome .emf
t
t
t
t
as time base. A high signal
Watchdog.emf
SPOC - BTS5590G
Rev. 1.3, 2007-10-30
Limp Home