GND disconnect
(channel 1/2 or 3/4)
BTS712N1
Inductive load switch-off energy
dissipation
E bb
Vbb
Ibb
IN1
Vbb
OUT1
IN2 PROFET
OUT2
ST
GND
VIN1VIN2 VST
V
GND
IN
Vbb
E AS
ELoad
PROFET OUT
=
ST
GND
L
{Z L
EL
ER
RL
Any kind of load. In case of IN = high is VOUT ≈ VIN - VIN(T+).
Due to VGND > 0, no VST = low signal available.
GND disconnect with GND pull up
(channel 1/2 or 3/4)
IN1
VIN1
IN2
VIN2
ST
Vbb
PROFET
OUT1
OUT2
GND
Energy stored in load inductance:
EL = 1/2·L·I2L
While demagnetizing load inductance, the energy
dissipated in PROFET is
∫ EAS= Ebb + EL - ER= VON(CL)·iL(t) dt,
with an approximate solution for RL > 0 Ω:
EAS= 2IL·R· LL(Vbb + |VOUT(CL)|)
ln
(1+
IL·RL
|VOUT(CL)|
)
Vbb
VST
VGND
Maximum allowable load inductance for
a single switch off (one channel)5)
L = f (IL ); Tj,start = 150°C, Vbb = 12 V, RL = 0 Ω
Any kind of load. If VGND > VIN - VIN(T+) device stays off
Due to VGND > 0, no VST = low signal available.
L [mH]
1000
Vbb disconnect with energized inductive
load
IN1
Vbb
high
OUT1
IN2 PROFET
OUT2
ST
GND
100
10
Vbb
For an inductive load current up to the limit defined by EAS
(max. ratings see page 3 and diagram on page 10) each
switch is protected against loss of Vbb.
Consider at your PCB layout that in the case of Vbb dis-
1
connection with energized inductive load the whole load
1
1.5
2
2.5
3
current flows through the GND connection.
IL [A]
Semiconductor Group
10
2004-Mar-11