Inverse Operation Behavior
of the BTS6143 and its family members
Introduction
V
S
V
ON
R
IN
IN
IS
V
IN
V
IS
R
Sense
VBB
OUT
V
OUT
R
Load
I
L
GND
ApplicationExample.emf
Figure 1
Typical application example with normal operation conditions
Whenever the device is commanded ON by pulling the pin IN to ground, a positive current +I
L
is flowing from the
pin VBB through the power stage out of the output pin OUT towards the load R
Load
. This operation condition is the
“normal operation condition” of the device.
Depending on the switched load type and specific application conditions a current flow opposite to the normal
operation condition can occur. This condition is called “inverse operation condition”. The characteristic of any
inverse operation condition is a positive supply voltage +V
S
, but a load current -I
L
opposite to the normal load
current direction.
Figure 2
shows a typical example.
+V
S
-V
ON
R
IN
IN
IS
+V
IN
+V
IS
R
Sense
VBB
OUT
+V
OUT
-I
L
M
InverseCondition.emf
GND
Figure 2
Inverse operation condition example
During inverse operation the current -I
L
flows from the pin OUT to the pin VBB.
Inverse operation conditions can occur whenever the voltage at the pin OUT becomes higher an the voltage at the
pin VBB. Examples for such conditions are:
•
the device drives a load which can also operate as generator. A typical load is a motor load. Due to external
conditions the motor is operated for a certain duration as a generator and supplies therefore a voltage higher
than the battery voltage
(example1: front windshield wiper in a driving car where the wiper is partly driven by the air flow;
example2: battery voltage drop while secondary driven motor is still rotating due to its inertia)
the device drives loads that can “store” energy. In such condition the stored energy can be fed back in case
the supply voltage drops (example: OUT is buffered with a very high capacitor,
V
S
drops due to external
conditions).
•
Application Note
3
V1.1, 2008-03-31