Datasheet

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.
PIN FUNCTIONS
UUU
Z (Pin 10): Inverting Driver Output.
B (Pin 11): Inverting Receiver Input.
A (Pin 12): Noninverting Receiver Input.
V
DD
(Pin 14): Positive Supply, 5V to ±5%. Bypass with
0.1µF 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
U
U
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
V
OD
Y
Z
R
R
V
OC
1686/87 • F01
Figure 1. Driver DC Test Load
RECEIVER
OUTPUT
C
L
15pF
1k
S1
S2
TEST POINT
V
DD
1k
1686/87 F02
Figure 2. Driver DC Test Load
OUTPUT
UNDER TEST
C
L
S1
S2
V
DD
500Ω
1686/87 F04
Figure 3. Driver/Receiver Timing Test Circuit Figure 4. Driver Timing Test Load #2
3V
DE
Y
Z
D
R
DIFF
C
L1
C
L2
R
15pF
A
B
RE
1686/87 F03