Data Sheet BTS555
Infineon Technologies AG 10 2008-June-24
Inverse load current operation
PROFET
V
IN
OUT
IS
bb
V
bb
V
OUT
- I
L
R
IS
V
IS
V
IN
+
-
+
-
I
IS
The device is specified for inverse load current
operation (V
OUT
> V
bb
> 0V). The current sense feature
is not available during this kind of operation (I
IS
= 0).
With I
IN
= 0 (e.g. input open) only the intrinsic drain
source diode is conducting resulting in considerably
increased power dissipation. If the device is switched
on (V
IN
= 0), this power dissipation is decreased to the
much lower value R
ON(INV)
* I
2
(specifications see page
4).
Note: Temperature protection during inverse load
current operation is not possible!
Inductive load switch-off energy
dissipation
PROFET
V
IN
OUT
IS
bb
E
E
E
E
AS
bb
L
R
E
Load
L
R
L
{
Z
L
R
IS
I
IN
V
bb
i (t)
L
Energy stored in load inductance:
E
L
=
1
/
2
·L·I
2
L
While demagnetizing load inductance, the energy
dissipated in PROFET is
E
AS
= E
bb
+ E
L
- E
R
=
∫
V
ON(CL)
·i
L
(t) dt,
with an approximate solution for R
L
> 0
Ω:
E
AS
=
I
L
· L
2
·R
L
(V
bb
+ |V
OUT(CL)
|) ln (1+
I
L
·R
L
|V
OUT(CL)
|
)
Maximum allowable load inductance for
a single switch off
L = f (I
L
); T
j,start
=
150°C, V
bb
= 12 V, R
L
= 0 Ω
L [µH]
I
L
[A]
Externally adjustable current limit
If the device is conducting, the sense current can be
used to reduce the short circuit current and allow
higher lead inductance (see diagram above). The
device will be turned off, if the threshold voltage of T2
is reached by I
S
*R
IS
. After a delay time defined by
R
V
*C
V
T1 will be reset. The device is turned on again,
the short circuit current is defined by I
L(SC)
and the
device is shut down after t
d(SC)
with latch function.
PROFET
IS
IN
IS
R
V
R
Powe
GND
Signal
GND
V
bb
OUT
V
C
load
R
T1
T2
IN
Signal
V
bb
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