These high gain series couplers use a Light Emitting Diode and an integrated high gain photodetector to provide extremely high current transfer ratio between input and output. Separate pins for the photodiode and output stage result in LVTTL compatible saturation voltages and high speed operation. Where desired, the VCC and VO terminals may be tied together to achieve conventional photodarlington operation. A base access terminal allows a gain bandwidth adjustment to be made. These optocouplers are for use in LVTTL/LVCMOS or other low power applications. A 400% minimum current transfer ratio is guaranteed over 0°C to +70°C operating range for only 0.5 mA of LED current. The HCPL-070L and HCPL-073L are surface-mount devices packaged in an industry-standard SOIC-8 footprint. The SOIC-8 does not require through holes in a PCB. This package occupies approximately one-third the footprint area of the standard dual-in-line package. The lead profile is designed to be compatible with standard surface-mount processes.