LT1089

5

1089fa

Driving Ground Referred Loads

Driving Negative Referred Loads

Driving Inductive Loads

LT1089 • TA01

12V

LOGIC

IN

LT1089

LT1089 • TA02

12V

–5V

LOGIC

IN

LT1089

LT1089 • TA03

12V

20V

LOGIC

IN

LT1089

TYPICAL APPLICATIO S

APPLICATIO HI TS

The logic and ground pins function as a differential logic

Note that if either Logic In or GND are left open the switch

remains inactive.

The LT1089 must be protected against overvoltage at

turn-off when driving inductive loads. The inductive flyback

voltage can easily exceed the maximum operating switch

switch. The solution is to clamp the switch voltage to 20V

or less with a zener diode. Remember that the switch can

handle 7.5A and the Zener may be required to handle the

same amount of current.

Care must be exercised when operating near the

maximum switch voltage. A high current or capacitive load

may trip the current limit circuit at turn-on, thereby

then governed by the current limit divided by the load

capacitance, while the falltime is a function of the complex

load. In addition, at switch voltages greater than 18V

the switch current must be less than 0.5A or the device

output will not pull up. Check the short circuit current

characteristics for more detailed information.