Datasheet

LT1785/LT1785A/
LT1791/LT1791A
8
178591fc
TEST CIRCUITS
Figure 1. Driver DC Test Load Figure 2. Receiver Timing Test Load
Figure 3. Driver/Receiver Timing Test Circuit Figure 4. Driver Timing Test Load
V
OD
A
B
R
R
V
OC
1785/91 F01
RECEIVER
OUTPUT
C
RL
1k
S1
S2
TEST POINT
V
CC
1k
1785/91 F02
5V
DE
A
B
DI
R
DIFF
C
L1
C
L2
RO
15pF
A
B
RE
1785/91 F03
OUTPUT
UNDER TEST
C
L
S1
S2
V
CC
500Ω
1785/91 F04
LT1785 Transmitting
INPUTS OUTPUTS
RE DE DI A B RO
0100 1 0
0111 0 1
1 0 X Hi-Z Hi-Z Hi-Z
1 1 0 0 1 Hi-Z
1 1 1 1 0 Hi-Z
LT1785 Receiving
INPUTS OUTPUT
RE DE DI A-B RO
0 0 X ≤ –200mV 0
0 0 X ≥ 200mV* 1
0 0 X Open 1
1 0 X X Hi-Z
* ≥ 0mV for LT1785A
LT1791
INPUTS OUTPUTS
RE DE DI A-B Y Z RO
0 0 X ≤ –200mV Hi-Z Hi-Z 0
0 0 X ≥ 200mV* Hi-Z Hi-Z 1
0 0 X Open Hi-Z Hi-Z 1
0 1 0 ≤ –200mV 0 1 0
0 1 0 ≥ 200mV* 0 1 1
0 1 0 Open 0 1 1
0 1 1 ≤ –200mV 1 0 0
0 1 1 ≥ 200mV* 1 0 1
0 1 1 Open 1 0 1
1 0 X X Hi-Z Hi-Z Hi-Z
1 1 0 X 0 1 Hi-Z
1 1 1 X 1 0 Hi-Z
* ≥ 0mV for LT1791A
FUNCTION TABLES