LTC1696

10

APPLICATIO S I FOR ATIO

Back-to-Back N-Channel MOSFET

A power management circuit that uses the LTC1696 to

control external back-to-back N-channel MOSFET at low

supply voltage is shown in Figure 3. In standby mode, the

drain of the external N-channel MOSFET, Q1, is pulled high

by the power management controller when the LTC1696

OUT pin is in the low state. The LTC1696 drives the gate of

Q1 high during an overvoltage fault condition. This pulls

the drain of Q1 low and turns off the back-to-back N-

channel MOSFETs.

C1

1nF

6

5

4

1696 F03

1

2

3

LTC1696

RESET

1.8V

Q2

2N7002

FB1

GND

FB2

OUT

TIMER/

RESET

R1

44.2k

1%

1.5V

3.3V

R2

38.3k

1%

R3

44.2k

1%

Q1

2N7002

N-CHANNEL

×2

PRIMARY

INPUT

SUPPLY

R4

54.9k

1%

C2

0.1

µF

POWER MANAGEMENT

CONTOLLER

Figure 3. Back-to-Back N-Channel MOSFETs for Low Supply Application