Datasheet

Data Sheet 29 Rev. 2.1, 2011-09-01
PROFET™+ 12V
BTS5045-2EKA
Diagnostic Functions
7.3 SENSE Signal in the Nominal Current Range
Figure 21 and Figure 22 show the current sense as a function of the load current in the power DMOS. Usually, a
pull-down resistor
R
IS
is connected to the IS pin. This resistor has to be higher than 560 Ω to limit the power losses
in the sense circuitry. A typical value is 1.2 kΩ. The blue curve represents the ideal SENSE, assuming an ideal
k
ILIS
factor value. The red curves show the accuracy the device provides across full temperature range, at a
defined current.
Figure 21 Current Sense for Nominal Load
7.3.1 SENSE Signal Variation as a Function of Temperature and Load Current
In some applications a better accuracy is required around half the nominal current I
L(NOM)
. To achieve this accuracy
requirement, a calibration on the application is possible. To avoid multiple calibration points at different load and
temperature conditions, the BTS5045-2EKA allows limited derating of the
k
ILIS
value, at nominal load current (I
L3
;
T
J
= +25 °C). This derating is described by the parameter Δk
ILIS
. Figure 22 shows the behavior of the SENSE
current, assuming one calibration point at nominal load at +25 °C.
The blue line indicates the ideal
k
ILIS
ratio.
The green lines indicate the derating on the parameter across temperature and voltage, assuming one calibration
point at nominal temperature and nominal battery voltage.
The red lines indicate the
k
ILIS
accuracy without calibration.
0,0
1,0
2,0
3,0
4,0
5,0
6,0
01234567
I
L
[A]
I
IS
[m A ]
K
ILIS ideal
I
IS
=
kilis BTS5045
k
ilis4
K
ilis3
K
ilis2
K
ilis1
I
L