Datasheet

9
LTC1155
Dual 2A Autoreset Electronic Fuse
U
SA
O
PP
L
IC
AT
ITY
P
I
CA
L
U
S
A
O
PP
L
IC
AT
I
WU
U
I FOR ATIO
Overvoltage Protection
The MOSFET and load can be protected against overvolt-
age conditions by using the circuit of Figure 6. The drain
sense function is used to detect an overvoltage condition
and quickly discharge the power MOSFET gate. The 18V
zener diode conducts when the supply voltage exceeds
Figure 5. Reverse Battery Protection
1155 F05
LOAD
LTC1155
GND
GND
G1
DS1
V
S
IN1
V
S
= 4.5V TO 18V
C
DLY
R
SEN
R
DLY
100k
5V
300Ω
1/4W
10µF
25V
+
18.6V and pulls the drain sense pin 0.6V below the supply
pin voltage.
The supply voltage is limited to 18.6V and the gate drive is
immediately removed from the MOSFET to ensure that it
cannot conduct during the overvoltage period. The gate of
the MOSFET will be latched OFF until the supply transient
is removed and the input turned OFF and ON again.
Figure 6. Overvoltage Shutdown and Protection
1155 F06
LOAD
LTC1155
GND
GND
G1
DS1
V
S
IN1
V
S
= 4.5V TO 18V
510Ω
10k 1N4148
18V
1155 TA03
0.03Ω
10µF
1/2 SI9956DY
30k
LTC1155
GND
IN1
IN2
DS2V
S
DS1
0.03Ω
G2
G1
0.1µF
30k
0.1µF
5V
100k
1/2 SI9956DY
1N4148
1N4148
OUT 1 OUT 2
100k
750k
1.0µF
LMC555
6
1
2
3
84
f
O
= 1Hz
ALL COMPONENTS SHOWN ARE SURFACE MOUNT
+