Logic device/transceiver/encoder

The MC100EL91 is a triple PECL input-ECL output converter. The device accepts standard and low-voltage differential PECL signals (determined by VCC) and converts them to differential -5 V ECL output signals. (For conversion to -3.3 V ECL output, see MC100LVEL91.) For level translation, the EL91 requires three power rails. The VCC power supply should be connected to the positive power supply, and the VEE pin should be connected to the negative power supply. The GND pin should be connected to the system ground plane. VEE and VCC should be bypassed to ground with 0.01 µF capacitors. In an open input condition, the Dbar input will be biased at VCC/2 and the D input will be pulled to ground. This condition will force the Q output low, ensuring stability. Only the VBB pin, the internally generated supply voltage, is provided for this device. In the case of single-ended inputs, tie the unused differential input to VBB as the switch reference voltage. VBB can also re-bias the AC-coupled input. When used, decouple VBB and VCC with 0.01 µF capacitors and limit source/sink current to 0.5 mA. VBB should be left open when not in use.