CY7B992

The CY7B991 and CY7B992 Programmable Skew Clock Buffers (PSCB) offer user-selectable control over system clock functions. These multiple-output clock drivers provide the system integrator with functions necessary to optimize the timing of high-performance computer systems. Eight individual drivers, arranged as four pairs of user-controllable outputs, can each drive terminated transmission lines with impedances as low as 50 while delivering minimal and specified output skews and full-swing logic levels (CY7B991 TTL or CY7B992 CMOS).

Each output can be hardwired to one of nine delay or function configurations. Delay increments of 0.7 to 1.5 ns are determined by the operating frequency with outputs able to skew up to ±6 time units from their nominal "zero" skew position. The completely integrated PLL allows external load and transmission line delay effects to be canceled. When this "zero delay" capability of the PSCB is combined with the selectable output skew functions, the user can create output-to-output delays of up to ±12 time units.

Divide-by-two and divide-by-four output functions are provided for additional flexibility in designing complex clock systems. When combined with the internal PLL, these divide functions allow distribution of a low-frequency clock that can be multiplied by two or four at the clock destination. This facility minimizes clock distribution difficulty while allowing maximum system clock speed and flexibility.