Optically Coupled 20 mA Current Loop Receiver

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The HCPL-4200 4 to 20 mA receiver is designed to operate as a receiver 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 20 mA current loop to the logic output breaks ground loops and provides for a very high common mode rejection.It aids in the design process by providing guaranteed thresholds for logic high state and logic low state for the current loop, providing an LSTTL, TTL, or CMOS compatible logic interface, and providing guaranteed common mode rejection. The buffer circuit on its current loop side provides typically 0.8 mA of hysteresis which increases the immunity to common mode and differential mode noise. The buffer also provides a controlled amount of LED drive current which takes into account any LED light output degradation. The internal shield allows a guaranteed 1000 V/ms common mode transient immunity.



  • Data Output Compatible with LSTTL, TTL and CMOS
  • 20 K Baud Data Rate at 1400 Metres Line Length
  • Guaranteed On and Off Thresholds
  • LED is Protected from Excess Current
  • Input Threshold Hysteresis
  • Three-State Output Compatible with Data Buses
  • Internal Shield for High Common Mode Rejection
  • Safety Approval:
    UL Recognized - 3750 V rms for 1 Minute
    CSA Approved
  • Optically Coupled 20 mA Current Loop Transmitter, HCPL-4100, Also Available
  • Options available are:
300 = Gull Wing Surface Mount Lead Option
500 = Tape/Reel Packaging Option (1 K min.)
XXXE = Lead Free Option


  • Isolated 20 mA Current
  • Loop Receiver in:
    Computer Peripherals
    Industrial Control Equipment
    Data Communications Equipment

Lifecycle Status


Substance Compliance

  • RoHS
    Pb & Pb-free options available
Specification Value
Lifecycle Active
Distrib. Inventory Yes
CMR (min.) (V/µs) 1000.0
Vcm (V) 50.0
RoHS6 Compliant Pb & Pb-free options available
Package 300mil DIP
Product Type 20 mA Current Loop Receiver
Prop Delay (tPHL) Max. (µs) 1.6
Prop Delay tPHL Uom µs
Prop Delay (tPLH) Max. (µs) 1.6
Prop Delay tPLH Uom µs
VDD2 (V) 5.0
Prop Delay (tPHL) Max. (µs) 1.6 µs
Prop Delay (tPLH) Max. (µs) 1.6 µs
Application Brief1 i
Application Note7 i
Brochures2 i
Design Guide1 i
FAQs2 i
Obsolescence Notice1 i
Options Data Sheet6 i
Product Change Notice (PCN)17 i
Regulatory Certificate2 i
Reliability Data Sheet5 i
Selection Guide2 i
White Papers3 i
Promotional Material1 i