Datasheet

Datasheet 21 Rev. 1.0, 2008-08-28
Smart High-Side Power Switch
BTS50080-1TEA
Diagnosis
7 Diagnosis
For diagnosis purpose, the BTS50080-1TEA provides an enhanced sense signal at the pin IS.
The pin IS provides during normal operation a sense current, which is proportional to the load current as long as
V
bIS
> 5 V. The ratio of the output current is defined as k
ILIS
= I
L
/I
IS
. During switch-on no current is provided, until
the forward voltage drops below
V
ON
< 1 V typ. The output sense current is limited to I
IS(lim)
.
The pin IS provides in case of any fault conditions a defined fault current
I
IS(fault)
as long as V
bIS
>8V
.
Fault
conditions are overcurrent (
V
ON
> 1 V typ.), current limit or overtemperature switch off.
The pin IS provides no current during open load in ON and de-energisation of inductive loads.
Figure 17 Block Diagram: Diagnosis
The accuracy of the provided current sense ratio (
k
ILIS
= I
L
/ I
IS
) depends on the load current. Please refer to
Figure 18 for details. A typical resistor
R
IS
of 1 kΩ is recommended.
Sense. emf
R
bb
V
IS
V
b,I S
I
IS(fault)
V
bb
R
IS
I
IS
IS
V
Z,IS
Table 1 Truth Table
Parameter Input Current Level Output Level Current Sense
I
IS
Normal operation L
1)
H
1)
L
H
≈ 0 (I
IS(LL)
)
nominal
Overload L
H
L
H
≈ 0 (
I
IS(LL)
)
I
IS(fault)
Short circuit to GND L
H
L
L
≈ 0 (I
IS(LL)
)
I
IS(fault)
Overtemperature L
H
L
L
≈ 0 (I
IS(LL)
)
I
IS(fault)
Short circuit to V
bb
L
H
H
H
≈ 0 (I
IS(LL)
)
< nominal
2)
Open load L
H
Z
1)
H
≈ 0 (
I
IS(LL)
)
≈ 0 (
I
IS(LH)
)
1) H = “High” Level, L = “Low” Level, Z = high impedance, potential depends on external circuit
2) Low ohmic short to V
bb
may reduce the output current I
L
and therefore also the sense current I
IS
.