ISL3178E Intersil Corporation, ISL3178E Datasheet - Page 12

• Manufacturer Part Number: ISL3178E
• Description: (ISL3170E - ISL3178E) RS-485/RS-422 Transceivers
• Manufacturer: Intersil Corporation

The driver output stages incorporate short circuit current
limiting circuitry which ensures that the output current never
exceeds the RS-485 spec, even at the common mode
voltage range extremes. Additionally, these devices utilize a
foldback circuit which reduces the short circuit current, and
thus the power dissipation, whenever the contending voltage
exceeds either supply.
In the event of a major short circuit condition, devices also
include a thermal shutdown feature that disables the drivers
whenever the die temperature becomes excessive. This
eliminates the power dissipation, allowing the die to cool. The
drivers automatically re-enable after the die temperature
drops about 15 degrees. If the contention persists, the thermal
shutdown/re-enable cycle repeats until the fault is cleared.
Receivers stay operational during thermal shutdown.
Typical Performance Curves
ISL3170E, ISL3171E, ISL3172E, ISL3173E, ISL3174E, ISL3175E, ISL3176E, ISL3177E, ISL3178E
-100
-150
FIGURE 7. DRIVER OUTPUT CURRENT vs DIFFERENTIAL
200
150
100
FIGURE 9. DRIVER OUTPUT CURRENT vs SHORT CIRCUIT
-50
50
120
100
0
80
60
40
20
-7 -6
0
0
OUTPUT VOLTAGE
VOLTAGE
-4
0.5
DIFFERENTIAL OUTPUT VOLTAGE (V)
ISL317XE
Y OR Z = LOW
-2
1
OUTPUT VOLTAGE (V)
0
1.5
12
2
Y OR Z = HIGH
2
ISL3170E thru ISL3175E
4
6
V
2.5
ISL3176E/77/78E
CC
= 3.3V, T
8
3
10
A
= +25°C; Unless Otherwise Specified
3.5
12
Low Power Shutdown Mode
These CMOS transceivers all use a fraction of the power
required by their bipolar counterparts, but some also include
a shutdown feature that reduces the already low quiescent
I
whenever the receiver and driver are simultaneously
disabled (RE = V
600ns. Disabling both the driver and the receiver for less
than 50ns guarantees that the transceiver will not enter
shutdown.
Note that receiver and driver enable times increase when the
transceiver enables from shutdown. Refer to Notes 7-11, at the
end of the Electrical Specification table, for more information.
CC
FIGURE 8. DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs
0.52
0.51
0.49
0.48
0.47
0.46
0.5
2.35
2.25
2.15
2.05
1.95
1.85
to a 10nA trickle. These devices enter shutdown
2.3
2.2
2.1
1.9
FIGURE 10. SUPPLY CURRENT vs TEMPERATURE
-40
2
-40
-25
-25
TEMPERATURE
ISL3170/3/6E, DE = X, RE = 0V; ISL3171/4/7E
CC
ISL3172/5/8E, DE = V
R
ISL3172/5/8E, DE = 0V, RE = 0V
DIFF
and DE = GND) for a period of at least
TEMPERATURE (°C)
TEMPERATURE (°C)
0
0
= 54Ω
R
DIFF
25
25
= 100Ω
CC
, RE = X
50
50
August 28, 2006
75
75
FN6307.2
85
85