IDT IDT2308A User Manual

IDT2308A

3.3V ZERO DELAY CLOCK MULTIPLIER

COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES

3.3V ZERO DELAY CLOCK MULTIPLIER

FEA TURES:

• Phase-Lock Loop Clock Distribution for Applications ranging from 10MHz to 133MHz operating frequency

• Distributes one clock input to two banks of four outputs

• Separate output enable for each output bank

• External feedback (FBK) pin is used to synchronize the outputs to the clock input

• Output Skew <200 ps

• Low jitter <200 ps cycle-to-cycle

• 1x, 2x, 4x output options (see table):

– IDT2308A-1 1x – IDT2308A-2 1x, 2x – IDT2308A-3 2x, 4x – IDT2308A-4 2x – IDT2308A-1H and -2H for High Drive

• No external RC network required

• Operates at 3.3V VDD

• Available in SOIC and TSSOP packages

IDT2308A

DESCRIPTION:

The IDT2308A is a high-speed phase-lock loop (PLL) clock multiplier. It is designed to address high-speed clock distribution and multiplication applications. The zero delay is achieved by aligning the phase between the incoming clock and the output clock, operable within the range of 10 to 133MHz.

The IDT2308A has two banks of four outputs each that are controlled via two select addresses. By proper selection of input addresses, both banks can be put in tri-state mode. In test mode, the PLL is turned off, and the input clock directly drives the outputs for system testing purposes. In the absence of an input clock, the IDT2308A enters power down. In this mode, the device will

draw less than 12µA for Commercial Temperature range and less than 25µA for Industrial temperature range, and the outputs are tri-stated.

The IDT2308A is available in six unique configurations for both prescaling and multiplication of the Input REF Clock. (See available options table.)

The PLL is closed externally to provide more flexibility by allowing the user

to control the delay between the input clock and the outputs.

The IDT2308A is characterized for both Industrial and Commercial opera-

tion.

FUNCTIONAL BLOCK DIAGRAM

(-3, -4)

FBK

REF

PLL

Control

Logic

(-2, -3)

CLKA1

CLKA2

CLKA3

CLKA4

CLKB1

CLKB2

CLKB3

The IDT logo is a registered trademark of Integrated Device Technology, Inc.

COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES

2004 Integrated Device Technology, Inc. DSC 6587/8c

CLKB4

JULY 2004

IDT2308A

3.3V ZERO DELAY CLOCK MULTIPLIER

COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES

PIN CONFIGURATION

REF

CLKA1

CLKA2

VDD

GND

CLKB1

CLKB2

SOIC/ TSSOP

TOP VIEW

PIN DESCRIPTION

Pin Number Functional Description

(1)

REF

(2)

CLKA1

(2)

CLKA2

VDD 4 3.3V Supply

GND 5 Ground

(2)

CLKB1

(2)

CLKB2

(3)

(2)

CLKB3

(2)

CLKB4

GND 12 Ground

VDD 13 3.3V Supply

(2)

CLKA3

(2)

CLKA4

FBK 16 PLL Feedback Input

1 Input Reference Clock, 5 Volt Tolerant Input 2 Clock Output for Bank A 3 Clock Output for Bank A

6 Clock Output for Bank B 7 Clock Output for Bank B 8 Select Input, Bit 2

9 Select Input, Bit 1 1 0 Clock Output for Bank B 1 1 Clock Output for Bank B

1 4 Clock Output for Bank A 1 5 Clock Output for Bank A

161

ABSOLUTE MAXIMUM RATINGS

Symbol Rating Max. Unit

VDD Supply Voltage Range –0.5 to +4.6 V

(2)

FBK

VI V

I Input Voltage Range –0.5 to V

CLKA4

CLKA3

GND

CLKB4

CLKB3

IIK (VI < 0) Input Clamp Current –5 0 mA IO Continuous Output Current ±50 mA (VO = 0 to VDD) VDD or GND Continuous Current ±100 mA TA = 55°C Maximum Power Dissipation 0.7 W (in still air) TSTG Storage Temperature Range –65 to +150 °C Operating Commercial Temperature 0 to +70 °C Temperature Range Operating Industrial Temperature -40 to +85 °C Temperature Range

NOTES:

1. Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may

2. The input and output negative-voltage ratings may be exceeded if the input and output

3. The maximum package power dissipation is calculated using a junction temperature

(3)

cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability.

clamp-current ratings are observed.

of 150°C and a board trace length of 750 mils.

Input Voltage Range (REF) –0.5 to +5.5 V

(except REF) VDD+0.5

(1)

APPLICATIONS:

• SDRAM

• Telecom

• Datacom

• PC Motherboards/Workstations

• Critical Path Delay Designs

NOTES:

1. Weak pull down.

2. Weak pull down on all outputs.

3. Weak pull ups on these inputs.

IDT2308A

3.3V ZERO DELAY CLOCK MULTIPLIER

COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES

FUNCTION TABLE

S2 S1 CLK A CLK B Output Source PLL Shut Down

L L Tri-State Tri-State PLL Y

L H Driven Tri-State PLL N H L Driven Driven REF Y H H Driven Driven PLL N

NOTE:

1. H = HIGH Voltage Level L = LOW Voltage Level

(1)

SELECT INPUT DECODING

AVAILABLE OPTIONS FOR IDT2308A

Device Feedback From Bank A Frequency Bank B Frequency

IDT2308A-1 Bank A or Bank B Reference Reference

IDT2308A-1H Bank A or Bank B Reference Reference

IDT2308A-2 Bank A Reference Reference/2

IDT2308A-2 Bank B 2 x Reference Reference IDT2308A-2H Bank A Reference Reference/2 IDT2308A-2H Bank B 2 x Reference Reference

IDT2308A-3 Bank A 2 x Reference Reference or Reference

IDT2308A-3 Bank B 4 x Reference 2 x Reference

IDT2308A-4 Bank A or Bank B 2 x Reference 2 x Reference

NOTE:

1. Output phase is indeterminant (0° or 180° from input clock).

(1)

ZERO DELA Y AND SKEW CONTROL

To close the feedback loop of the IDT2308A, the FBK pin can be driven from any of the eight available output pins. The output driving the FBK pin will be driving a total load of 7pF plus any additional load that it drives. The relative loading of this output (with respect to the remaining outputs) can adjust the input-output delay.

For applications requiring zero input-output delay, all outputs including the one providing feedback should be equally loaded. Ensure the outputs are loaded equally, for zero output-output skew.

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