9

LTC1155

Dual 2A Autoreset Electronic Fuse

S

APPLICATI

TYPICAL

S

APPLICATI

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

IN1

100k

5V

300

Ω

1/4W

10

µF

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

IN1

510

Ω

10k

1N4148

18V

1155 TA03

0.03

Ω

10

µF

1/2 SI9956DY

30k

LTC1155

GND

IN1

IN2

DS2

DS1

0.03

Ω

G2

G1

0.1

µF

30k

0.1

µF

5V

100k

1/2 SI9956DY

1N4148

1N4148

OUT 1

OUT 2

100k

750k

1.0

µF

LMC555

6

1

2

3

84

ALL COMPONENTS SHOWN ARE SURFACE MOUNT

+