TEXAS INSTRUMENTS CDC2510C Technical data

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CDC2510C

3.3-V PHASE-LOCK LOOP CLOCK DRIVER

SCAS621 – DECEMBER 1998

D

Designed to Meet PC SDRAM Registered
DIMM Design Support Document Rev. 1.2

D

Spread Spectrum Clock Compatible

D

Operating Frequency 25 MHz to 125 MHz

D

Static tPhase Error Distribution at 66 MHz
to 100 MHz is ±150 ps

D

Drop-In Replacement for TI CDC2510A With
Enhanced Performance

D

Jitter (cyc – cyc) at 66 MHz to 100 MHz is
|100 ps|

D

Available in Plastic 24-Pin TSSOP

D

Phase-Lock Loop Clock Distribution for
Synchronous DRAM Applications

D

Distributes One Clock Input to One Bank of
Ten Outputs

D

External Feedback (FBIN) Terminal Is Used
to Synchronize the Outputs to the Clock
Input

D

On-Chip Series Damping Resistors

D

No External RC Network Required

D

Operates at 3.3 V

AGND

V

CC

1Y0
1Y1

1Y2
GND
GND

1Y3

1Y4

V

CC

FBOUT

PW PACKAGE

(TOP VIEW)

1
2
3
4
5
6
7
8
9
10

G

11
12

24
23
22
21
20
19
18
17
16
15
14
13

CLK
AV

CC

V

CC

1Y9
1Y8
GND
GND
1Y7
1Y6
1Y5
V

CC

FBIN

description

The CDC2510C 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 (FBOUT) output to the clock (CLK) input signal.
It is specifically designed for use with synchronous DRAMs. The CDC2510C operates at V
provides integrated series-damping resistors that make it ideal for driving point-to-point loads.

One bank of ten outputs provides ten low-skew, low-jitter copies of CLK. Output signal duty cycles are adjusted
to 50 percent, independent of the duty cycle at CLK. All outputs can be enabled or disabled via a single output
enable input. When the G input is high, the outputs switch in phase and frequency with CLK; when the G input
is low, the outputs are disabled to the logic-low state.

Unlike many products containing PLLs, the CDC2510C 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 CDC2510C 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 AV

to ground.

CC

The CDC2510C is characterized for operation from 0°C to 85°C.
For application information refer to application reports

CDC509/516/2509/2510/2516
Spectrum Clocking (SSC)

(literature number SLMA003) and

(literature number SCAA039).

High Speed Distribution Design Techniques for

Using CDC2509A/2510A PLL with Spread

= 3.3 V . It also

CC

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

Copyright  1998, Texas Instruments Incorporated

1

CDC2510C

3.3-V PHASE-LOCK LOOP CLOCK DRIVER

SCAS621 – DECEMBER 1998

FUNCTION TABLE

INPUTS

G CLK

X L L L

L HLH

HHHH

functional block diagram

11

G

OUTPUTS

1Y

(0:9)

FBOUT

3

1Y0

4

1Y1

5

1Y2

CLK

FBIN

AV

CC

24

13

23

PLL

AVAILABLE OPTIONS

PACKAGE

T

A

0°C to 85°C CDC2510CPWR

SMALL OUTLINE

(PW)

15

16

17

20

21

12

8

9

1Y3

1Y4

1Y5

1Y6

1Y7

1Y8

1Y9

FBOUT

2

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

TYPE

DESCRIPTION

3.3-V PHASE-LOCK LOOP CLOCK DRIVER

Terminal Functions

TERMINAL

NAME NO.

Clock input. CLK provides the clock signal to be distributed by the CDC2510C clock driver. CLK is
used to provide the reference signal to the integrated PLL that generates the clock output signals. CLK

CLK 24 I

FBIN 13 I

G 11 I

FBOUT 12 O

3, 4, 5, 8, 9

CC

15, 16, 17, 20,

21

23 Power

2, 10, 14, 22 Power Power supply

1Y (0:9)

AV

AGND 1 Ground Analog ground. AGND provides the ground reference for the analog circuitry.

V

CC

GND 6, 7, 18, 19 Ground Ground

must have a fixed frequency and fixed phase for the PLL to obtain phase lock. Once the circuit is
powered up and a valid CLK signal is applied, a stabilization time is required for the PLL to phase lock
the feedback signal to its reference signal.

Feedback input. FBIN provides the feedback signal to the internal PLL. FBIN must be hardwired to
FBOUT to complete the PLL. The integrated PLL synchronizes CLK and FBIN so that there is
nominally zero phase error between CLK and FBIN.

Output bank enable. G is the output enable for outputs 1Y(0:9). When G is low, outputs 1Y(0:9) are
disabled to a logic-low state. When G is high, all outputs 1Y(0:9) are enabled and switch at the same
frequency as CLK.

Feedback output. FBOUT is dedicated for external feedback. It switches at the same frequency as
CLK. When externally wired to FBIN, FBOUT completes the feedback loop of the PLL. FBOUT has
an integrated 25-Ω series-damping resistor.

Clock outputs. These outputs provide low-skew copies of CLK. Output bank 1Y(0:9) is enabled via
the G input. These outputs can be disabled to a logic-low state by deasserting the G control input.

O

Each output has an integrated 25-Ω series-damping resistor.
Analog power supply . A VCC provides the power reference for the analog circuitry. In addition, A V

can be used to bypass the PLL for test purposes. When AVCC is strapped to ground, PLL is bypassed
and CLK is buffered directly to the device outputs.

CDC2510C

SCAS621 – DECEMBER 1998

CC

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

3

CDC2510C

3.3-V PHASE-LOCK LOOP CLOCK DRIVER

SCAS621 – DECEMBER 1998

absolute maximum ratings over operating free-air temperature range (unless otherwise noted)

Supply voltage, AV
Supply voltage range, V
Input voltage range, V
Voltage range applied to any output in the high
or low state, V

O

Input clamp current, I
Output clamp current, I
Continuous output current, I
Continuous current through each V
Maximum power dissipation at T
Storage temperature range, T

†

Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

NOTES: 1. AVCC must not exceed VCC.

2. The input and output negative-voltage ratings may be exceeded if the input and output clamp-current ratings are observed.

3. This value is limited to 4.6 V maximum.

4. The maximum package power dissipation is calculated using a junction temperature of 150°C and a board trace length of 750 mils.
For more information, refer to the

Book

, literature number SCBD002.

(see Note 1) AVCC < VCC +0.7 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CC

, AVCC –0.5 V to 4.6 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CC

(see Note 2) –0.5 V to 6.5 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

I

(see Notes 2 and 3) –0.5 V to VCC + 0.5 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(V

< 0) –50 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IK

I

(V

< 0 or VO > VCC) ±50 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

OK

O

(V

= 0 to VCC) ±50 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

O

O

or GND ±100 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CC

= 55°C (in still air) (see Note 4) 0.7 W. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

A

–65°C to 150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

stg

Package Thermal Considerations

application note in the

ABT Advanced BiCMOS T echnology Data

recommended operating conditions (see Note 5)

MIN MAX UNIT

VCC, AVCCSupply voltage 3 3.6 V
V

IH

V

IL

V

I

I

OH

I

OL

T

A

NOTE 5: Unused inputs must be held high or low to prevent them from floating.

High-level input voltage 2 V
Low-level input voltage 0.8 V
Input voltage 0 V
High-level output current –12 mA
Low-level output current 12 mA
Operating free-air temperature 0 85 °C

CC

V

†

timing requirements over recommended ranges of supply voltage and operating free-air
temperature

MIN MAX UNIT

f

clk

†

Time required for the integrated PLL circuit to obtain phase lock of its feedback signal to its reference signal. For phase lock to be obtained, a
fixed-frequency , fixed-phase reference signal must be present at CLK. Until phase lock is obtained, the specifications for propagation delay, skew ,
and jitter parameters given in the switching characteristics table are not applicable. This parameter does not apply for input modulation under
SSC application.

4

Clock frequency 25 125 MHz
Input clock duty cycle 40% 60%
Stabilization time

†

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1 ms