The MC100LVE210 is a low voltage, low skew dual differential ECL fanout buffer designed with clock distribution in mind. The device features two fanout buffers, a 1:4 and a 1:5 buffer, on a single chip. The device features fully differential clock paths to minimize both device and system skew. The dual buffer allows for the fanout of two signals through a single chip, thus reducing the skew between the two fundamental signals from a parttopart skew down to an outputtooutput skew. This capability reduces the skew by a factor of 4 as compared to using two LVE111's to accomplish the same task. The MC100LVE210 works from a 3.3V supply while the MC100E210 provides identical function and performance from a standard 4.5V 100E voltage supply. For applications which require a singleended input, the VBB reference voltage is supplied. For singleended input applications the VBB reference should be connected to the unused CLK input of a differential pair and bypassed to ground via a 0.01f capacitor. The input signal is then driven into the selected CLK input. To ensure that the tight skew specification is met it is necessary that both sides of the differential output are identically terminated, even if only one side is being used. In most applications all nine differential pairs will be used and therefore terminated. In the case where fewer than nine pairs are used it is necessary to terminate at least the output pairs adjacent to the output pair being used in order to maintain minimum skew. Failure to follow this guideline will result in small degradations of propagation delay (on the order of 1020ps) of the outputs being used, while not catastrophic to most designs this will result in an increase in skew. Note that the package corners isolate outputs from one another such that the guideline expressed above holds only for outputs on the same side of the package. The MC100LVE210, as with most ECL devices, can be operated from a positive VCC supply in PECL mode. This allows the LVE210 to be used for high performance clock distribution in +3.3V systems. Designers can take advantage of the LVE210's performance to distribute low skew clocks across the backplane or the board. In a PECL environment series or Thevenin line terminations are typically used as they require no additional power supplies, if parallel termination is desired a terminating voltage of VCC2.0V will need to be provided. For more information on using PECL, designers should refer to Application Note AN1406/D. Dual Differential Fanout Buffers 200ps ParttoPart Skew