LT1785/LT1785A
LT1791/LT1791A
DC ELECTRICAL CHARACTERISTICS
The
q
denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C, V
CC
= 5V.
SYMBOL
V
OD1
V
OD2
PARAMETER
Differential Driver Output Voltage (Unloaded)
Differential Driver Output Voltage (With Load)
CONDITIONS
I
O
= 0
R = 50Ω (RS422), Figure 1
R = 27Ω (RS485), Figure 1
R = 18Ω
R = 27Ω or R = 50Ω, Figure 1
R = 27Ω or R = 50Ω, Figure 1
R = 27Ω or R = 50Ω, Figure 1
DI, DE, RE
DI, DE, RE
DI, DE, RE
V
IN
= 12V
V
IN
= – 7V
– 60V
≤
V
IN
≤
60V
LT1785/LT1791: – 7V
≤
V
CM
≤
12V
LT1785A/LT1791A: – 7V
≤
V
CM
≤
12V
– 7V < V
CM
< 12V
I
O
= – 400µA, V
ID
= 200mV
I
O
= 1.6mA, V
ID
= – 200mV
RE > 2V or Power Off
– 7V
≤
V
CM
≤
12V
– 60V
≤
V
CM
≤
60V
– 7V
≤
V
CM
≤
12V
V
OUT
= HIGH, Force V
O
= – 7V
V
OUT
= LOW, Force V
O
= 12V
V
O
= 60V
V
O
= – 60V
0V
≤
V
O
≤
V
CC
–7V
≤
V
O
≤
12V
– 60V
≤
V
O
≤
60V
No Load, RE = 0V, DE = 5V
No Load, RE = 5V, DE = 5V
No Load, RE = 0V, DE = 0V
No Load, RE = 5V, DE = 0V
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
MIN
2.0
1.5
1.2
TYP
4.1
2.70
2.45
2.2
MAX
5
UNITS
V
V
V
V
∆V
OD
V
OC
∆
V
OC
V
IH
V
IL
I
IN1
I
IN2
Change in Magnitude of Driver Differential Output
Voltage for Complementary Output States
Driver Common Mode Output Voltage
Change in Magnitude of Driver Common Mode
Output Voltage for Complementary Output States
Input High Voltage
Input Low Voltage
Input Current
Input Current (A, B); (LT1791 or LT1785 with
DE = 0V)
Differential Input Threshold Voltage for Receiver
Receiver Input Hysteresis
Receiver Output High Voltage
Receiver Output Low Voltage
Three-State (High Impedance) Output Current
at Receiver 0V < V
OUT
< 6V
0.2
2
2.5
3
0.2
2
0.8
5
– 0.15
–6
– 0.2
– 0.2
20
3.5
–1
85
50
35
35
–6
±30
– 0.2
–6
5.5
5.5
4.5
0.2
0.3
6
9
9
8
0.3
125
125
90
0.25
250
250
6
4
0.3
0.5
1
0.15
– 0.08
0.3
6
0.2
0
V
V
V
V
V
µA
mA
mA
mA
V
V
mV
V
V
µA
kΩ
kΩ
kΩ
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
V
TH
∆V
TH
V
OH
V
OL
R
IN
Receiver Input Resistance (LT1791)
LT1785
RS485 Unit Load
I
SC
Driver Short-Circuit Current
Driver Output Fault Current
Receiver Short-Circuit Current
Driver Three-State Output Current
q
q
q
q
q
q
q
q
q
q
q
I
CC
Supply Current
3
LINER [ LINEAR TECHNOLOGY ]
