The ELS511 series devices each consist of an infrared emitting diode, optically coupled to a high speed photo detector transistor. A separate connection for the photodiode bias and output-transistor collector increase the speed by several orders of magnitude over conventional phototransistor couplers by reducing the base-collector capacitance of the input transistor. The ELS611 series devices consist of an infrared emitting diode optically coupled to a high speed integrated photo detector logic gate with a storable output.
Their dimensions of 9.7×4.58×3.38mm, half of those of a 6N13X series (8-Pin), greatly eases use in designs with limited PCB area, making them suitable for space constrained industrial applications like high speed ground isolation.