The MC100EL90 is a triple ECL to PECL translator. The device receives either -3.3 V or-5 V differential ECL signals determined by the VEE supply level and translates them to standard +5 V differential PECL output signals. To accomplish the level translation the EL90 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 as expected are connected to the system ground plane. Both VEE and VCC should be bypassed to ground via 0.01 F capacitors. Under open input conditions the D input will be biased at VEE/2 and the D input will be pulled to VEE . 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 F capacitor and limit current sourcing or sinking to 0.5 mA. When not used VBB should be left open.