Datasheet

Datasheet 18 Rev. 1.1, 2008-02-28
Smart Low Side Power Switch
HITFET - BTS3160D
Power Stage
6.3 Inductive Output Clamp
When switching off inductive loads with low-side switches, the Drain Source voltage V
D
rises above battery
potential, because the inductance intends to continue driving the current.
The BTS3160D is equipped with a voltage clamp mechanism that keeps the Drain-Source voltage V
D
at a certain
level. See
Figure 15 for more details.
OutputClamp.emf
GND
Drain
Figure 15 Output Clamp
InductiveLoad.emf
IN
Low
High
t
t
Von
V
bb
t
I
D
V
DAZ
Overtemperature or
short circuit detected
Figure 16 Switching an inductance
While demagnetization of inductive loads, energy has to be dissipated in the BTS3160D. This energy can be
calculated with following equation:
EV
DS(CL)
V
bb
V–
DS(CL)
R
L
-----------------------------------
ln⋅ 1
R
L
I
L
⋅
V
bb
V–
DS(CL)
-----------------------------------–



I
L
+
L
R
L
------
⋅⋅=
Following equation simplifies under assumption of R
L
= 0
E
1
2
---
LI
L
2
1
V
bb
V
bb
V–
DS(CL)
-----------------------------------–



⋅=