IDT IDT2308 Technical data

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IDT2308

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):

– IDT2308-1 1x
– IDT2308-2 1x, 2x
– IDT2308-3 2x, 4x
– IDT2308-4 2x
– IDT2308-1H, -2H, and -5H for High Drive

• No external RC network required

• Operates at 3.3V VDD

• Available in SOIC and TSSOP packages

IDT2308

DESCRIPTION:

The IDT2308 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 IDT2308 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 IDT2308 enters power down, and the outputs are tri-stated. In
this mode, the device will draw less than 25µA.

The IDT2308 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 IDT2308 is characterized for both Industrial and Commercial operation.
NOTE: For new designs, refer to AN-233.

FUNCTIONAL BLOCK DIAGRAM

(-3, -4)

16

FBK

REF

S2

S1

2

1

2

(-5)

8

9

PLL

Control

Logic

(-2, -3)

2

CLKA1

3

CLKA2

14

CLKA3

15

CLKA4

2

6

CLKB1

7

CLKB2

10

CLKB3

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

COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES

2003 Integrated Device Technology, Inc. DSC 5173/9c

1

11

CLKB4

APRIL 2003

IDT2308

3.3V ZERO DELAY CLOCK MULTIPLIER

COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES

PIN CONFIGURATION

REF

CLKA1
CLKA2

VDD

GND
CLKB1
CLKB2

S2

2
3
4

5
6

7
8

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)

S2

(3)

S1

(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
15
14
13
12

11
10

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

DD

V

GND
CLKB4

CLKB3

9

S1

IIK (VI < 0) Input Clamp Current –5 0 mA
IOK Terminal Voltage with Respect ±50 mA
(VO < 0 or VO > VDD) to GND (inputs VIH 2.5, VIL 2.5)
I

O 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.

2

IDT2308

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 IDT2308

Device Feedback From Bank A Frequency Bank B Frequency

IDT2308-1 Bank A or Bank B Reference Reference

IDT2308-1H Bank A or Bank B Reference Reference

IDT2308-2 Bank A Reference Reference/2

IDT2308-2 Bank B 2 x Reference Reference
IDT2308-2H Bank A Reference Reference/2
IDT2308-2H Bank B 2 x Reference Reference

IDT2308-3 Bank A 2 x Reference Reference or Reference

IDT2308-3 Bank B 4 x Reference 2 x Reference

IDT2308-4 Bank A or Bank B 2 x Reference 2 x Reference
IDT2308-5H Bank A or Bank B Reference/2 Reference/2

NOTE:

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

(1)

3

IDT2308

3.3V ZERO DELAY CLOCK MULTIPLIER

COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES

ZERO DELA Y AND SKEW CONTROL

To close the feedback loop of the IDT2308, 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. If input-output delay
adjustments are required, use the Output Load Difference Chart to calculate loading differences between the feedback output and remaining outputs.
Ensure the outputs are loaded equally, for zero output-output skew.

REF TO CLKA/CLKB DELAY vs. OUTPUT LOAD DIFFERENCE BETWEEN FBK PIN AND CLKA/CLKB PINS

1500

1000

500

0

-30 -25 -20

-500

REF to CLKA/CLKB Delay (ps)

-1000

-1500

OUTPUT LOAD DIFFERENCE BETWEEN FBK PIN AND CLKA/CLKB PINS ( pF)

-15

-10

-5

05

10 15 20 25

30

4