TPS40190
SLUS658A – JULY 2005 – REVISED AUGUST 2005
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APPLICATION INFORMATION (continued)
RELATIVE SHORT CIRCUIT THRESHOLD CHANGE
vs
TEMPERATURE
1.3
FET
Resistance
1.2
Relative Change
1.1
1.0
0.9
Short Circuit
Threshold
Voltage
0.8
0.7
−50
−25
75
T
J
−
Junction Temperature
−
°C
0
25
50
100
Figure 3.
Table 1. Short Circuit Threshold Voltage Selection
Short Circuit Protection
Resistance
R
COMP
(kΩ)
10.8 to 13.2
OPEN
3.6 to 4.4
Nominal Current Limit
Voltage
V
ILIM
(mV)
460
320
160
The range of short circuit current thresholds that can be expected is given by
Equation 1
and
Equation 2.
V
ILIM(max)
I
SCP(max)
+
R
DS(onMIN)
I
SCP(min)
+
V
ILIM(min)
R
DS(onMAX)
(1)
(2)
where
•
•
•
I
SCP
is the short circuit current
V
ILIM
is the short circuit threshold
R
DS(on)
is the channel resistance of the high-side MOSFET
8
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