Datasheet

Datasheet 17 Rev. 1.0, 2008-01-23
Smart High-Side Power Switch
BTS50080-1TMA
Protection Functions
6.3 Reverse Polarity Protection - Reversafe
®
The device can not block a current flow in reverse polarity condition. In order to minimize power dissipation, the
device offers Reversave
®
functionality. In reverse polarity condition the channel will be switched on provided a
sufficient gate to source voltage is generated
V
GS
≈ V
Rbb
. Please refer to Figure 14 for details.
Figure 14 Reverse battery protection
Additional power is dissipated by the integrated
R
bb
resistor. Use following formula for estimation of overall power
dissipation
P
diss(rev)
in reverse polarity mode.
For reverse battery voltages up to
V
bb
< 16 V the pin IN or the pin IS should be low ohmic connected to signal
ground. This can be achieved e.g. by using a small signal diode D in parallel to the input switch or by using a small
signal MOSFET driver. For reverse battery voltages higher then
V
bb
= 16 V an additional resistor R
IN
is
recommended. The overall current through
R
bb
should not be above 80 mA.
Note: No protection mechanism is active during reverse polarity. The IC logic is not functional.
Reverse.emf
IN
-I
L
LOAD
R
bb V
bb
R
IN Logic
IS
R
IS
-V
bb
-I
IN
power groundsignal ground
-I
IS
I
Rbb
D
P
diss(rev)
R
ON(rev)
I
L
2
⋅ R
bb
I
Rbb
2
⋅+≈
1
R
IN
---------
1
R
IS
--------
+
0.08A
V
bb
12V–
-------------------------------=