115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

2540

QUAD DARLINGTON

POWER DRIVER

APPLICATIONS INFORMATION

A typical application is shown for driving four high-current relays,

solenoids, or print heads. A Zener diode is used to increase the

flyback voltage, providing a much faster inductive load turn-off current

decay, resulting in faster dropout (reduced relay contact arcing), and

improved performance. The maximum Zener voltage, plus the load

supply voltage, plus the flyback diode forward voltage must not exceed

the device’s rated sustaining voltage.

With external control circuitry, the ENABLE input can be used for

chopper (PWM) applications. If the ENABLE input is not used, it

should be tied high.

All inputs will float high if open circuited.

Dwg. WP-001

TYPICAL APPLICATION

(QUAD RELAY DRIVER WITH ZENER FLYBACK)

Dwg. EP-016

+5V

4

IN

ENABLE

IN

2

+28 V

K

K

4

3

15V

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

ZENER CLAMP

DIODE CLAMP

V

+ V

CC

F

V

+ V + V

CC

Z

F