Dual Channel Low Input Current, High Gain Optocouplers

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This dual channel optocoupler contains a separated pair of GaAsP light emitting diodes optically coupled to a pair of integrated high gain photo detectors. It provides extremely high current transfer ratio and excellent input-output common mode transient immunity. A separate pin for the photodiodes and first gain stages (VCC) permits lower output saturation voltage and higher speed operation possible with conventional photodarlington type optocouplers. In addition, VCC may be as low as 1.6 V without adversely affecting the parametric performance. It is available in an 8-pin DIP package.

Guaranteed operation at low input currents and the high current transfer ratio (CTR) reduce the magnitude and effects of CTR degradation.

The outstanding high temperature performance of this split Darlington type output amplifier results from the inclusion of an integrated emitter-base bypass resistor which shunts photodiode and first stage leakage currents to grounds.

The HCPL-2731 has a 400% minimum CTR at an input current of only 0.5 mA making it ideal for use in low input current applications such as MOS, CMOS, and low power logic interfacing or RS232C data transmission systems. In addition, the high CTR and high output current capability make this device extremely useful in applications where high fanout is required. Compatibility with high voltage CMOS logic systems is guaranteed by the 18 V VCC and VO specifications and by testing output high leakage (IOH) at 18 V.

Important specifications such as CTR, leakage current, output saturation voltage are guaranteed over the 0 degrees C to 70 degrees C temperature range to allow trouble-free system operation. Selection for lower input currents down to 250 mA is available upon request.


  • High Current Transfer Ratio - 1800% Typical
  • Low Input Current Requirements - 0.5 mA
  • Low Output Saturation Voltage - 0.1 V
  • High Density Packaging
  • Performance Guaranteed over Temperature 0 degrees C to 70 degrees C
  • LSTTL Compatible
  • High Output Current - 60 mA
  • Safety Approval:
UL Recognized - 3750 V rms for 1 Minute and 5000 V rms for 1 Minute (Option 020)
CSA Approved
  • Available in 8 Pin DIP and SO-8 Footprint
  • Surface Mount Gull Wing Option Available for 8-Pin DIP (Option 300)
  • Options available are:
020 = 5000 V rms/1 Minute UL Rating Option
300 = Gull Wing Surface Mount Option
500 = Tape and Reel Packaging Option
XXXE = Lead Free Option


  • Digital Logic Ground Isolation
  • Telephone Ring Detector
  • Level Shifting
  • EIA RS-232C Line Receiver
  • Polarity Sensing
  • Low Input Current Line Receiver - Long Line or Party Line
  • Microprocessor Bus Isolation
  • Current Loop Receiver
  • Line Voltage Status Indicator - Low Input Power Dissipation

Lifecycle Status


Substance Compliance

  • RoHS
    Pb & Pb-free options available
Specification Value
Lifecycle Active
Distrib. Inventory Yes
RoHS6 Compliant Pb & Pb-free options available
Product Type 100 KBd Darlington Transistor Output
Package 300mil DIP-8
VDD (V) 5
IF Min. (mA) 0.5
CTR Min. (%) 400.0
CTR Max. (%) 5000
Prop Delay (tPLH) Max. (µs) 60.0
Prop Delay (tPHL) Max. (µs) 20.0
CMR (min.) (V/µs) 1000.0
Vcm (V) 10.0
UL Insulation Rating Viso (VRMS) 5000.0
IEC Maximum Working Insulation Voltage Viorm (VPEAK) 630
Application Brief1 i
Application Note7 i
Brochures2 i
Data Sheet1 i
Design Guide1 i
FAQs2 i
Obsolescence Notice1 i
Options Data Sheet6 i
Product Change Notice (PCN)17 i
Regulatory Certificate2 i
Reliability Data Sheet3 i
Selection Guide2 i
White Papers3 i
Promotional Material1 i