6

LTC1686/LTC1687

DE (Pin 4): Driver Enable. DE = high enables the driver.

DE = low will force the driver output into a high impedance

state. Do not float.

D (Pin 5): Driver Input. Controls the states of the Y and Z

outputs when DE = high. Do not float.

GND (Pins 6, 7): Ground.

Y (Pin 9): Noninverting Driver Output.

Z (Pin 10): Inverting Driver Output.

B (Pin 11): Inverting Receiver Input.

A (Pin 12): Noninverting Receiver Input.

0.1

µF ceramic capacitor.

Receiving

INPUTS

OUTPUT

RE

DE

A – B

R

0X

≥ 300mV

1

0X

≤ –300mV

0

0

X

Inputs Open

1

0

X

Inputs Shorted Together

1

A = B = – 7V to 12V

1

X

X

Hi- Z

FU CTIO TABLES

Transmitting

INPUTS

LINE

OUTPUTS

RE

DE

D

CONDITION

Z

Y

X

1

1

No Fault

0

1

X

1

0

No Fault

1

0

X

0

X

X

Hi- Z

Hi- Z

X

1

X

Fault

±10mA Current

Source

(LTC1687)

TEST CIRCUITS

Y

Z

R

R

1686/87 • F01

Figure 1. Driver DC Test Load

RECEIVER

OUTPUT

15pF

1k

S1

S2

TEST POINT

1k

1686/87 F02

Figure 2. Driver DC Test Load

OUTPUT

UNDER TEST

S1

S2

500

Ω

1686/87 F04

Figure 3. Driver/Receiver Timing Test Circuit

Figure 4. Driver Timing Test Load #2

3V

DE

Y

Z

D

R

15pF

A

B

RE

1686/87 F03