CY23EP09

Document #: 38-07760 Rev. *C

Page 4 of 17

Zero Delay and Skew Control

All outputs should be uniformly loaded to achieve Zero Delay

between the input and output. Since the CLKOUT pin is the

internal feedback to the PLL, its relative loading can adjust the

input-output delay.

The output driving the CLKOUT pin will be driving a total load of

5 pF plus any additional load externally connected to this pin. For

applications requiring zero input-output delay, the total load on

each output pin (including CLKOUT) must be the same. If

input-output delay adjustments are required, the CLKOUT load

may be changed to vary the delay between the REF input and

remaining outputs.

For zero output-output skew, be sure to load all outputs equally.

For further information refer to the application note entitled

“CY2305 and CY2309 as PCI and SDRAM Buffers”.

Notes

1. Weak pull-down.

2. Weak pull-down on all outputs.

3. Weak pull-ups on these inputs.

4. This output is driven and has an internal feedback for the PLL. The load on this output can be adjusted to change the skew between the reference and output.

Pin Definition

Pin

Signal

Description

1REF[1]

Input reference frequency

2

CLKA1[2]

Buffered clock output, Bank A

3

CLKA2[2]

Buffered clock output, Bank A

3.3 V or 2.5 V supply

5

GND

Ground

6

CLKB1[2]

Buffered clock output, Bank B

7

CLKB2[2]

Buffered clock output, Bank B

8S2[3]

Select input, bit 2

9S1[3]

Select input, bit 1

10

CLKB3[2]

Buffered clock output, Bank B

11

CLKB4[2]

Buffered clock output, Bank B

12

GND

Ground

13

3.3 V or 2.5 V supply

14

CLKA3[2]

Buffered clock output, Bank A

15

CLKA4[2]

Buffered clock output, Bank A

16

CLKOUT[2]

Buffered output, internal feedback on this pin

Select Input Decoding

S2

S1

CLOCK A1–A4

CLOCK B1–B4

CLKOUT[4]

Output Source

PLL Shutdown

0

0

Three-state

Three-state

Driven

PLL

N

0

1

Driven

Three-state

Driven

PLL

N

1

0

Driven

Driven

Driven

Reference

Y

1

1

Driven

Driven

Driven

PLL

N

[+] Feedback