1
IDT2305
3.3V ZERO DELAY CLOCK BUFFER
COMMERCIALAND INDUSTRIAL TEMPERATURE RANGES
APRIL 2001
2001 Integrated Device Technology, Inc.
DSC-5174/2
c
IDT2305
FUNCTIONAL BLOCK DIAGRAM
3.3V ZERO DELAY
CLOCK BUFFER
FEATURES:
Phase-Lock Loop Clock Distribution
10MHz to 133MHz operating frequency
Distributes one clock input to one bank of five outputs
Zero Input-Output Delay
Output Skew < 250ps
Low jitter < 200ps cycle-to-cycle
IDT2305-1 for Standard Drive
IDT2305-1H for High Drive
Industrial Temperature Available
No external RC network required
Operates at 3.3V V
DD
Available in SOIC package
Power Down Mode
PLL
8
CLK1
CLK2
CLK3
CLK4
Control
Logic
REF
CLKOU T
1
3
2
5
7
DESCRIPTION:
The IDT2305 is a high-speed phase-lock loop (PLL) clock buffer,
designed to address high-speed clock distribution 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 IDT2305 is an 8-pin version of the IDT2309. IDT2305 accepts one
reference input, and drives out five low skew clocks. The -1H version of this
device operates, up to 133MHz frequency and has a higher drive than the
-1 device. All parts have on-chip PLLs which lock to an input clock on the
REF pin. The PLL feedback is on-chip and is obtained from the CLKOUT
pad. In the absence of an input clock, the IDT2305 enters power down. In
this mode, the device will draw less than 25
A,
the outputs are tri-stated,
and the PLL is not running, resulting in a significant reduction of power.
The IDT2305 is characterized for both Industrial and Commercial
operation.
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
2
IDT2305
3.3V ZERO DELAY CLOCK BUFFER
COMMERCIALAND INDUSTRIAL TEMPERATURE RANGES
REF
CLK1
2
3
4
8
7
6
5
1
CLK2
GND
CLKOUT
CLK4
V
DD
CLK3
SO 8-1
PIN CONFIGURATION
APPLICATIONS:
SDRAM
Telecom
Datacom
PC Motherboards/Workstations
Critical Path Delay Designs
NOTES:
1. Weak pull down.
2. Weak pull down on all outputs.
SOIC
TOP VIEW
PIN DESCRIPTION
Pin Name
Pin Number
Type
Functional Description
REF
(1)
1
IN
Input reference clock, 5 Volt tolerant input
CLK2
(2)
2
Out
Output clock
CLK1
(2)
3
Out
Output clock
GND
4
Ground
Ground
CLK3
(2)
5
Out
Output clock
V
DD
6
PWR
3.3V Supply
CLK4
(2)
7
Out
Output clock
CLKOUT
(2)
8
Out
Output clock, internal feedback on this pin
ABSOLUTE MAXIMUM RATINGS
(1)
Symbol
Rating
Max.
Unit
V
DD
Supply Voltage Range
0.5 to +4.6
V
V
I (2)
Input Voltage Range (REF)
0.5 to +5.5
V
V
I
Input Voltage Range
(except REF)
0.5 to V
DD
+0.5
V
I
IK
(V
I
< 0)
Input Clamp Current
50
mA
I
O
(V
O
= 0 to V
DD
) Continuous Output Current
50
mA
V
DD
or GND
Continuous Current
100
mA
T
A
= 55C
(in still air)
(3)
Maximum Power Dissipation
0.7
W
T
STG
Storage Temperature Range
65 to +150
C
Operating
Temperature
Commercial Temperature Range
0 to +70
C
Operating
Temperature
Industrial Temperature Range
-40 to +85
C
NOTES:
1. Stresses greater than those listed under ABSOLUTE MAXIMUM
RATINGS may 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.
2. The input and output negative-voltage ratings may be exceeded if
the input and output clamp-current ratings are observed.
3. The maximum package power dissipation is calculated using a
junction temperature of 150
C and a board trace length of 750 mils.
3
IDT2305
3.3V ZERO DELAY CLOCK BUFFER
COMMERCIALAND INDUSTRIAL TEMPERATURE RANGES
NOTES:
1. REF Input has a threshold voltage of V
DD
/2.
2. All parameters specified with loaded outputs.
OPERATING CONDITIONS - COMMERCIAL
Symbol
Parameter
Min.
Max.
Unit
V
DD
Supply Voltage
3
3.6
V
T
A
Operating Temperature (Ambient Temperature)
0
70
C
C
L
Load Capacitance < 100MHz
--
30
pF
Load Capacitance 100 - 133MHz
--
10
C
IN
Input Capacitance
--
7
pF
DC ELECTRICAL CHARACTERISTICS - COMMERCIAL
Symbol
Parameter
Conditions
Min.
Max.
Unit
V
IL
Input LOW Voltage Level
--
0.8
V
V
IH
Input HIGH Voltage Level
2
--
V
I
IL
Input LOW Current
V
IN
= 0V
--
50
A
I
IH
Input HIGH Current
V
IN
= V
DD
--
100
A
V
OL
Output LOW Voltage
Standard Drive
I
OL
= 8mA
--
0.4
V
High Drive
I
OL
= 12mA (- 1H)
V
OH
Output HIGH Voltage
Standard Drive
I
OH
= -8mA
2.4
--
V
High Drive
I
OH
= -12mA (- 1H)
I
DD_PD
Power Down Supply Current
REF = 0MHz
--
12
A
I
DD
Supply Current
Unloaded outputs at 66.66 MHz
--
32
mA
SWITCHING CHARACTERISTICS (IDT2305-1) - COMMERCIAL
(1, 2)
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Unit
t
1
Output Frequency
10pF Load
10
--
133
MHz
30pF Load
10
--
100
Duty Cycle = t
2
t
1
Measured at 1.4V, F
OUT
= 66.66MHz
40
50
60
%
t
3
Rise Time
Measured between 0.8V and 2V
--
--
2.5
ns
t
4
Fall Time
Measured between 0.8V and 2V
--
--
2.5
ns
t
5
Output to Output Skew
All outputs equally loaded
--
--
250
ps
t
6
Delay, REF Rising Edge to CLKOUT Rising Edge
Measured at V
DD
/2
--
0
350
ps
t
7
Device-to-Device Skew
Measured at V
DD
/2 on the CLKOUT pins of devices
--
0
700
ps
t
J
Cycle-to-Cycle Jitter, pk - pk
Measured at 66.66MHz, loaded outputs
--
--
200
ps
t
LOCK
PLL Lock Time
Stable power supply, valid clock presented on REF pin
--
--
1
ms
4
IDT2305
3.3V ZERO DELAY CLOCK BUFFER
COMMERCIALAND INDUSTRIAL TEMPERATURE RANGES
NOTES:
1. REF Input has a threshold voltage of V
DD
/2.
2. All parameters specified with loaded outputs.
SWITCHING CHARACTERISTICS (IDT2305-1H) - COMMERCIAL
(1, 2)
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Unit
t
1
Output Frequency
10pF Load
10
--
133
MHz
30pF Load
10
--
100
Duty Cycle = t
2
t
1
Measured at 1.4V, F
OUT
= 66.66MHz
40
50
60
%
Duty Cycle = t
2
t
1
Measured at 1.4V, F
OUT
<50MHz
45
50
55
%
t
3
Rise Time
Measured between 0.8V and 2V
--
--
1.5
ns
t
4
Fall Time
Measured between 0.8V and 2V
--
--
1.5
ns
t
5
Output to Output Skew
All outputs equally loaded
--
--
250
ps
t
6
Delay, REF Rising Edge to CLKOUT Rising Edge
Measured at V
DD
/2
--
0
350
ps
t
7
Device-to-Device Skew
Measured at V
DD
/2 on the CLKOUT pins of devices
--
0
700
ps
t
8
Output Slew Rate
Measured between 0.8V and 2V using Test Circuit #2
1
--
--
V/ns
t
J
Cycle-to-Cycle Jitter, pk - pk
Measured at 66.66MHz, loaded outputs
--
--
200
ps
t
LOCK
PLL Lock Time
Stable power supply, valid clock presented on REF pin
--
--
1
ms
OPERATING CONDITIONS - INDUSTRIAL
Symbol
Parameter
Min.
Max.
Unit
V
DD
Supply Voltage
3
3.6
V
T
A
Operating Temperature (Ambient Temperature)
-40
85
C
C
L
Load Capacitance < 100MHz
--
30
pF
Load Capacitance 100 - 133MHz
--
10
C
IN
Input Capacitance
--
7
pF
DC ELECTRICAL CHARACTERISTICS - INDUSTRIAL
Symbol
Parameter
Conditions
Min.
Max.
Unit
V
IL
Input LOW Voltage Level
--
0.8
V
V
IH
Input HIGH Voltage Level
2
--
V
I
IL
Input LOW Current
V
IN
= 0V
--
50
A
I
IH
Input HIGH Current
V
IN
= V
DD
--
100
A
V
OL
Output LOW Voltage
Standard Drive
I
OL
= 8mA
--
0.4
V
High Drive
I
OL
= 12mA (- 1H)
V
OH
Output HIGH Voltage
Standard Drive
I
OH
= -8mA
2.4
--
V
High Drive
I
OH
= -12mA (- 1H)
I
DD_PD
Power Down Supply Current
REF = 0MHz
--
25
A
I
DD
Supply Current
Unloaded outputs at 66.66 MHz
--
35
mA
5
IDT2305
3.3V ZERO DELAY CLOCK BUFFER
COMMERCIALAND INDUSTRIAL TEMPERATURE RANGES
NOTES:
1. REF Input has a threshold voltage of V
DD
/2.
2. All parameters specified with loaded outputs.
SWITCHING CHARACTERISTICS (IDT2305-1) - INDUSTRIAL
(1,
2)
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Unit
t
1
Output Frequency
10pF Load
10
--
133
MHz
30pF Load
10
--
100
Duty Cycle = t
2
t
1
Measured at 1.4V, F
OUT
= 66.66MHz
40
50
60
%
t
3
Rise Time
Measured between 0.8V and 2V
--
--
2.5
ns
t
4
Fall Time
Measured between 0.8V and 2V
--
--
2.5
ns
t
5
Output to Output Skew
All outputs equally loaded
--
--
250
ps
t
6
Delay, REF Rising Edge to CLKOUT Rising Edge
Measured at V
DD
/2
--
0
350
ps
t
7
Device-to-Device Skew
Measured at V
DD
/2 on the CLKOUT pins of devices
--
0
700
ps
t
J
Cycle-to-Cycle Jitter, pk - pk
Measured at 66.66MHz, loaded outputs
--
--
200
ps
t
LOCK
PLL Lock Time
Stable power supply, valid clock presented on REF pin
--
--
1
ms
SWITCHING CHARACTERISTICS (IDT2305-1H) - INDUSTRIAL
(1, 2)
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Unit
t
1
Output Frequency
10pF Load
10
--
133
MHz
30pF Load
10
--
100
Duty Cycle = t
2
t
1
Measured at 1.4V, F
OUT
= 66.66MHz
40
50
60
%
Duty Cycle = t
2
t
1
Measured at 1.4V, F
OUT
<50MHz
45
50
55
%
t
3
Rise Time
Measured between 0.8V and 2V
--
--
1.5
ns
t
4
Fall Time
Measured between 0.8V and 2V
--
--
1.5
ns
t
5
Output to Output Skew
All outputs equally loaded
--
--
250
ps
t
6
Delay, REF Rising Edge to CLKOUT Rising Edge
Measured at V
DD
/2
--
0
350
ps
t
7
Device-to-Device Skew
Measured at V
DD
/2 on the CLKOUT pins of devices
--
0
700
ps
t
8
Output Slew Rate
Measured between 0.8V and 2V using Test Circuit #2
1
--
--
V/ns
t
J
Cycle-to-Cycle Jitter, pk - pk
Measured at 66.66MHz, loaded outputs
--
--
200
ps
t
LOCK
PLL Lock Time
Stable power supply, valid clock presented on REF pin
--
--
1
ms
6
IDT2305
3.3V ZERO DELAY CLOCK BUFFER
COMMERCIALAND INDUSTRIAL TEMPERATURE RANGES
REF to CLKA/CLKB Delay (ps)
ZERO DELAY AND SKEW CONTROL
All outputs should be uniformly loaded in order to achieve Zero I/O Delay. Since the CLKOUT pin is the internal feedback for the PLL, its relative
loading can affect and adjust the input/output delay. The Output Load Difference diagram illustrates the PLL's relative loading with respect to the other
outputs that can adjust the Input-Output (I/O) Delay.
For designs utilizing zero I/O Delay, all outputs including CLKOUT must be equally loaded. Even if the output is not used, it must have a capacitive
load equal to that on the other outputs in order to obtain true zero I/O Delay. If I/O Delay adjustments are needed, use the Output Load Difference diagram
to calculate loading differences between the CLKOUT pin and other outputs. For zero output-to-output skew, all outputs must be loaded equally.
REF TO CLKA/CLKB RELAY vs. OUTPUT LOAD DIFFERENCE BETWEEN CLKOUT PIN AND CLKA/CLKB PINS
OUTPUT LOAD DIFFERENCE BETWEEN CLKOUT PIN AND CLKA/CLKB PINS (pF)
1500
1000
500
0
-500
-1000
-1500
-30
-25
-20
-15
-10
-5
0
5
10
15
20
25
30
7
IDT2305
3.3V ZERO DELAY CLOCK BUFFER
COMMERCIALAND INDUSTRIAL TEMPERATURE RANGES
V
DD
OUTPUTS
V
DD
GND
GND
0.1
F
0.1
F
V
DD
OUTPUTS
10pF
V
DD
GND
GND
0.1
F
0.1
F
1K
1K
C
LO A D
CLK
O U T
C LK
O U T
O utput
1.4V
1.4V
t5
O utput
RE F
V
DD/
2
t6
O utput
C LK
O U T
D evice 1
t7
C LK
O U T
D evice 2
V
DD/
2
V
DD
/2
V
DD
/2
1.4V
1.4V
t2
t1
1.4V
2V
0.8V
t3
t4
0.8V
3.3V
0V
2V
Output
ALL OUTPUTS RISE/FALL TIME
INPUT TO OUTPUT PROPAGATION DELAY
DEVICE TO DEVICE SKEW
OUTPUT TO OUTPUT SKEW
DUTY CYCLE TIMING
TEST CIRCUIT 1
TEST CIRCUIT 2
SWITCHING WAVEFORMS
Test Circuit for all Parameters Except t8
Test Circuit for t8, Output Slew Rate On -1H Devices
TEST CIRCUITS
8
IDT2305
3.3V ZERO DELAY CLOCK BUFFER
COMMERCIALAND INDUSTRIAL TEMPERATURE RANGES
TYPICAL DUTY CYCLE
(1)
AND I
DD
TRENDS
(2)
FOR IDT2305-1
NOTES:
1. Duty Cycle is taken from typical chip measured at 1.4V.
2. I
DD
data is calculated from I
DD
= I
CORE
+ nCVf, where I
CORE
is the unloaded current. (n = Number of outputs; C = Capacitance load per output (F);
V = Supply Voltage (V); f = Frequency (Hz))
3
3.1
3.2
3.3
3.4
3.5
3.6
V
DD
(V)
40
42
44
46
48
50
52
54
56
58
60
Duty Cycle vs V
DD
(for 30pf loads over frequency - 3.3V, 25C)
33MH z
66MHz
100MHz
D
u
ty
C
y
c
l
e
(%
)
3
3.1
3.2
3.3
3.4
3.5
3.6
V
DD
(V)
40
42
44
46
48
50
52
54
56
58
60
Du ty C ycle vs V
D D
(for 10pF load s over frequency - 3.3V , 25C )
33MHz
66MH z
100M Hz
20
40
60
80
100
120
140
Frequency
(M Hz)
40
42
44
46
48
50
52
54
56
58
60
Duty Cycle vs Frequency
(for 30pf loads over temperature - 3.3V)
-40C
0C
25C
70C
85C
D
u
ty
C
y
c
l
e
(%
)
D
u
ty
C
y
c
l
e
(%
)
133M Hz
20
40
60
80
100
120
140
Frequency
(M Hz)
40
42
44
46
48
50
52
54
56
58
60
D uty C ycle vs F re qu ency
(for 10pF loads over tem perature - 3.3V )
-40C
0C
25C
70C
85C
D
u
ty
C
y
c
l
e
(%
)
0
2
4
6
8
Num ber of Loaded Outputs
0
20
40
60
80
100
120
140
I
DD
vs Number of Loaded Outputs
(for 30pf loads over frequency - 3.3V, 25C)
33MH z
66MHz
100MHz
I
DD
(m
A
)
0
2
4
6
8
Num ber of Loaded Outputs
0
20
40
60
80
100
120
140
I
D D
vs N um ber of Loade d O utputs
(for 10pF loads over frequency - 3.3V, 25C )
33MH z
66MHz
100MHz
I
DD
(m
A
)
9
IDT2305
3.3V ZERO DELAY CLOCK BUFFER
COMMERCIALAND INDUSTRIAL TEMPERATURE RANGES
TYPICAL DUTY CYCLE
(1)
AND I
DD
TRENDS
(2)
FOR IDT2305-1H
NOTES:
1. Duty Cycle is taken from typical chip measured at 1.4V.
2. I
DD
data is calculated from IDD = ICORE + nCVf, where ICORE is the unloaded current. (n = Number of outputs; C = Capacitance load per output (F);
V = Supply Voltage (V); f = Frequency (Hz))
3
3.1
3.2
3.3
3.4
3.5
3.6
V
DD
(V )
40
42
44
46
48
50
52
54
56
58
60
Duty C ycle vs V
DD
(for 30pf loads over frequency - 3.3V, 25C)
33MH z
66MH z
100M Hz
D
u
ty
C
y
c
l
e
(%
)
3
3.1
3.2
3.3
3.4
3.5
3.6
V
DD
(V )
40
42
44
46
48
50
52
54
56
58
60
D uty C ycle vs V
D D
(for 10pF load s over frequency - 3.3V , 25C )
33MH z
66MH z
100M Hz
20
40
60
80
100
120
140
Frequency
(M H z)
40
42
44
46
48
50
52
54
56
58
60
Duty C ycle vs F requency
(for 30pf loads over temperature - 3.3V)
-40C
0C
25C
70C
85C
D
u
ty
C
y
c
l
e
(%
)
D
u
ty
C
y
c
l
e
(%
)
133M Hz
20
40
60
80
100
120
140
Frequency
(M H z)
40
42
44
46
48
50
52
54
56
58
60
D u ty C ycle vs Frequ ency
(for 10pF loads over tem perature - 3.3V )
-40C
0C
25C
70C
85C
D
u
ty
C
y
c
l
e
(%
)
0
2
4
6
8
N um ber of Loaded O utputs
0
20
40
60
80
100
120
140
I
DD
vs N um ber of Loaded O utputs
(for 30pf loads over frequency - 3.3V, 25C)
33MH z
66MH z
100M Hz
I
DD
(m
A
)
0
2
4
6
8
N um ber of Loaded O utputs
0
20
40
60
80
100
120
140
I
D D
vs N um b er of Loa ded O utp uts
(for 10pF loads over frequency - 3.3V , 25C )
33MH z
66MH z
100M Hz
I
DD
(m
A
)
160
160
10
IDT2305
3.3V ZERO DELAY CLOCK BUFFER
COMMERCIALAND INDUSTRIAL TEMPERATURE RANGES
CORPORATE HEADQUARTERS
for SALES:
2975 Stender Way
800-345-7015 or 408-727-6116
Santa Clara, CA 95054
fax: 408-492-8674
www.idt.com*
*To search for sales office near you, please click the sales button found on our home page or dial the 800# above and press 2.
The IDT logo is a registered trademark of Integrated Device Technology, Inc.
ORDERING INFORMATION
Ordering Code
Package Type
Operating Range
IDT2305-1DC
8-Pin SOIC
Commercial
IDT2305-1DCI
8-Pin SOIC
Industrial
IDT2305-1HDC
8-Pin SOIC
Commercial
IDT2305-1HDCI
8-Pin SOIC
Industrial
IDT
XXXXX
XX
X
Package
Process
Device Type
2305-1
2305-1H
Zero Delay Clock Buffer
High Drive Output
DC
Small Outline (S O8-1)
Blank
I
Comm ercial (0
o
C to +70
o
C)
Industrial (-40
o
C to +85
o
C)
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