Use CDCVF2510A as a Replacement for

this Device

Phase-Lock Loop Clock Distribution for

Synchronous DRAM Applications

Distributes One Clock Input to Four Banks

of Four Outputs

Separate Output Enable for Each Output

Bank

External Feedback Pin (FBIN) Is Used to

Synchronize the Outputs to the Clock Input

On-Chip Series-Damping Resistors

No External RC Network Required

Operates at 3.3-V VCC

Packaged in Plastic 48-Pin Thin Shrink

Small-Outline Package

description

The CDC2516 is a high-performance, low-skew,

low-jitter, phase-lock loop (PLL) clock driver. It

uses a PLL to precisely align, in both frequency

and phase, the feedback output (FBOUT) to the

clock (CLK) input signal. It is specifically designed

for use with synchronous DRAMs. The CDC2516

operates at 3.3-V VCC and provides integrated

series-damping resistors that make it ideal for

driving point-to-point loads.

Four banks of four outputs provide 16 low-skew,

low-jitter copies of the input clock. Output signal

duty cycles are adjusted to 50 percent,

independent of the duty cycle at the input clock.

Each bank of outputs can be enabled or disabled

separately via the 1G, 2G, 3G, and 4G control

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

logic-low state.

Unlike many products containing PLLs, the CDC2516 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 CDC2516 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, as well as following any changes to the PLL reference or

feedback signals. The PLL may be bypassed for test purposes by strapping AVCC to ground.

The CDC2516 is characterized for operation from 0°C to 70°C.