H
Optically Coupled 20 mA
Current Loop Transmitter
Technical Data
HCPL-4100
Features
• Guaranteed 20 mA Loop
Parameters
• Data Input Compatible with
LSTTL, TTL and CMOS
Logic
• Guaranteed Performance
over Temperature (0
°
C to
70
°
C)
• Internal Shield for High
Common Mode Rejection
• 20 kBaud Data Rate at 400
Metres Line Length
• Guaranteed On and Off
Output Current Levels
• Safety Approval
UL Recognized -2500 V rms for
1 minute
CSA Approved
• Optically Coupled 20 mA
Current Loop Receiver,
HCPL-4200, Also Available
Description
The HCPL-4100 optocoupler is
designed to operate as a transmit-
ter in equipment using the 20 mA
current loop. 20 mA current loop
systems conventionally signal a
logic high state by transmitting
20 mA of loop current (MARK),
and signal a logic low state by
allowing no more than a few
milliamperes of loop current
(SPACE). Optical coupling of the
signal from the logic input to the
20 mA current loop breaks
ground loops and provides very
high immunity to common mode
interference.
Functional Diagram
The HCPL-4100 data input is
compatible with LSTTL, TTL, or
CMOS logic gates. The input
integrated circuit drives a GaAsP
LED. The light emitted by the
LED is sensed by a second inte-
grated circuit that allows 20 mA
to pass with a voltage drop of less
than 2.7 volts when no light is
emitted and allows less than 2 mA
to pass when light is emitted. The
transmitter output is capable of
withstanding 27 volts. The input
integrated circuit provides a
controlled amount of LED drive
current and takes into account
any LED light output degrada-
tion. The internal shield allows a
guaranteed 1000 V/µs common
mode transient immunity.
Applications
• Isolated 20 mA Current
Loop Transmitter in:
Computer Peripherals
Industrial Control Equipment
Data Communications
Equipment
A 0.1
µF
bypass capacitor connected between pins 8 and 5 is recommended.
CAUTION: It is advised that normal static precautions be taken in handling and assembly of this component to
prevent damage and/or degradation which may be induced by ESD.
5965-3581E
1-361
AGILENT [ AGILENT TECHNOLOGIES, LTD. ]
