BSP 742 T
disconnect with charged inductive
V
load
GND disconnect
bb
V
bb
V
bb
high
IN
OUT
IN
PROFET
OUT
PROFET
GND
GND
V
V
V
bb
IN
GND
V
bb
GND disconnect with GND pull up
Inductive Load switch-off energy
dissipation
V
bb
IN
OUT
PROFET
E
bb
E
AS
GND
E
E
Load
L
V
bb
V
V
V
IN
IN
OUT
PROFET
GND
bb
L
=
GND
Z
L
{
E
R
R
L
2
Energy stored in load inductance: E = ½ * L * I
L
While demagnetizing load inductance,
the enérgy dissipated in PROFET is
L
E
= E + E - E = V * i (t) dt,
bb ON(CL) L
AS
L
R
with an approximate solution for R > 0Ω:
L
I
L
* L
I
L
* R
L
E
A S
=
* (V bb +|V O U T ( C L )| ) * ln(1 +
)
2 * R
L
|V O U T ( C L )|
2004-01-27
Page 8
INFINEON [ Infineon ]
