Triple LVPECL/PECL Input to -5.0 V ECL Output Translator

The MC100EL91 is a triple PECL input to ECL output translator. The device receives standard or low voltage differential PECL signals, determined by the VCC supply level, and translates them to differential -5 V ECL output signals. (For translation to -3.3 V ECL output, see MC100LVEL91.)

To accomplish the level translation, the EL91 requires three power rails. The VCC supply should be connected to the positive supply, and the VEE pin should be connected to the negative power supply. The GND pins are connected to the system ground plane. Both VEE and VCC should be bypassed to ground via 0.01 µF capacitors. Under open input conditions, the Dbar input will be biased at VCC/2 and the D input will be pulled to GND. This condition will force the Q output to a low, ensuring stability. The VBB pin, an internally generated voltage supply, is available to this device only. For single-ended input conditions, the unused differential input is connected to VBB as a switching reference voltage. VBB may also rebias AC coupled inputs. When used, decouple VBB and VCC via a 0.01 µF capacitor and limit current sourcing or sinking to 0.5 mA. When not used, VBB should be left open.