6

the grounded input of the transmitter, and is less than 25V

negative with respect to the transmitter VCC. The current

mode system is totally unaffected by ground differential

noise of +2V at frequencies as high as 1MHz.

Propagation Delay

The worst case propagation delay of a transmitter and

receiver, connected as shown in Figure 4, can be

determined by adding the maximum delay shown on the

data sheet for the transmitter and receiver. These overall

switching characteristics are shown in Table B. For the entire

system, however, the propagation delay of the transmission

line must also be considered. This delay, of course, depends

on the length of the line and the characteristics of the line,

but in general, delays of between 1.5ns and 3.0ns per foot

can be expected.

TABLE B. OVERALL TRANSMITTER/RECEIVER SWITCHING

CHARACTERISTICS

CHARACTERISTICS

HS-245RH, HS-246RH

HS-248RH

UNITS

MIN

TYP

MAX

Propagation Delay

TPLH

-18

40

ns

Propagation Delay

TPHL

-18

40

ns

Duty Cycle Distortion

TPLH - TPHL

-

2

15

ns

NOTE:

VCC = +5V, VEE = -5V.

Schematics

FIGURE 6. HS-245RH

FIGURE 7. HS-246RH, HS-248RH

NOTES:

1. HS-246RH does not have 6K output pull-up resistors.

2. HS-248RH does not have 50

Ω input termination resistors.

IN

T1

2.7K

2.7K

2.0K

2.0K

380

Ω

12

3

4

300

Ω

T2

56

8

9

T3

10

11

12

13

14VCC

OUT

OUT

IN

IN

OUT

OUT

IN

IN

OUT

OUT

IN

R1

-INPUT

(R1) OUTPUT

3

(R1) +INPUT

2

7

2.7K

4.1K

6K

1

-INPUT

6

(R2)

+INPUT

5

14VCC

4

(R2)

-INPUT

10

+INPUT

9

13VCC

8

(R3)

(R3) OUTPUT

(R2) OUTPUT

(R3)

12VEE

11VEE

R2

R3

GND

50

Ω

(R1)

50

Ω

HS-245RH, HS-246RH, HS-248RH