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), eases the use in designs with limited PCB area to make them well suited for space constraint industrial applications like high speed ground isolation.