Avago Technologies ACPL-224-500E - Manual (Page 31)

AV02-4387EN 28 Avago Technologies
Description
The above differentially driven
circuit can use up to eight 6N138
optocouplers at various receivers
along the 90 m line. All stations are
isolated. The first station would draw
approximately 2.7 mA current, and
the last station 1.8 mA of LED drive
current. The output grounds of the
optocoup ler may be electrically
separate.
Performance of Circuit
• Typical signaling rate: 18 kBd
(faster signaling rates can be
obtained with HCNW139 and
6N139)
• Typical optocoupler propaga tion
delay time: t
PHL
= 2 µs; t
PLH
= 20 µs
• Up to 90 m distance
Benefits
• Simple, low­cost, multidrop cir-
cuit for low signaling rates
Alternative Avago Parts
1) HCPL-0700/01/30/31, HCPL-
M700/1, HCNW138/9, and HCPL-
2730/31 Low-Input Current
Optocouplers
2) HCPL-57XX, HCPL-67XX, and
6N140 Hermetically Sealed Low-
Input Current Optocouplers
3) HCPL-2300 High Speed, Low In-
put Current Optocoupler
Multidrop Line Receiver
Data Communications Applications
V O
7
5
6
8
2
3
4
1
X
6N138
+5 v
2.2 k Ω
I F
Y
560 Ω
UP TO 90 m 22 GA TW. PR. SHIELDED
1
X
1/2 DM8830
Y
2
X Y
3
X Y
6
X Y
7
X Y
8
X Y
39 Ω
39 Ω