PCK2509SL

The PCK2509SL is a high-performance, low-skew, low-jitter, phase-locked loop (PLL) clock driver. It uses a PLL to precisely align, in both frequency and phase, the feedback (FBOUT) output to the clock (CLK) input signal. It is specifically designed for use with synchronous DRAMs. The PCK2509SL operates at 3.3 V VCC and is input compatible with both 2.5 V and 3.3 V input voltage ranges. PCK2509SL also provides integrated series-damping resistors that make it ideal for driving point-to-point loads. One bank of five outputs and one bank of four outputs provide nine low-skew, low-jitter copies of CLK. Output signal duty cycles are adjusted to 50 percent, independent of the duty cycle at CLK. Each bank of outputs can be enabled or disabled separately via the control (1G and 2G) inputs. When the G inputs are high, the outputs switch in phase and frequency with CLK; when the G inputs are low, the outputs are disabled to the logiclow state.

Unlike many products containing PLLs, the PCK2509SL does not require external RC networks. The loop filter for the PLL is included on-chip, minimizing component count, board space, and cost. Because it is based on PLL circuitry, the PCK2509SL requires a stabilization time to achieve phase lock of the feedback signal to the reference signal. This stabilization time is required, following power up and application of a fixed-frequency, fixed-phase signal at CLK, and following any changes to the PLL reference or feedback signals. The

PLL can be bypassed for test purposes by strapping AVCC to ground. The PCK2509SL is characterized for operation from 0 °C to +70 °C.