LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-
3.3V LVPECL CLOCK GENERATOR
ICS8535I-21
Features
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Two differential 3.3V LVPECL outputs
Selectable CLK0 or CLK1 inputs for redundant and multiple
frequency fanout applications
CLK0 or CLK1 can accept the following input levels:
LVCMOS or LVTTL
Maximum output frequency: 266MHz
Translates LVCMOS and LVTTL levels to 3.3V LVPECL levels
Output skew: 20ps (maximum)
Part-to-part skew: 300ps (maximum)
Propagation delay: 1.6ns (maximum)
Additive phase jitter, RMS: 0.03ps (typical)
3.3V operating supply
-40°C to 85°C ambient operating temperature
Available in lead-free (RoHS 6) package
General Description
The ICS8535I-21 is a low skew, high performance
1-to-2 LVCMOS/LVTTL-to-3.3V LVPECL fanout
HiPerClockS™
buffer and a member of the HiPerClockS™ family of
High Performance Clock Solutions from IDT. The
ICS8535I-21 has two single-ended clock inputs. The
single-ended clock input accepts LVCMOS or LVTTL input levels
and translate them to 3.3V LVPECL levels. The clock enable is
internally synchronized to eliminate runt clock pulses on the output
during asynchronous assertion/deassertion of the clock enable
pin.
ICS
Guaranteed output and part-to-part skew characteristics make the
ICS8535I-21 ideal for those applications demanding well defined
performance and repeatability.
Block Diagram
CLK_EN
Pullup
D
Q
CLK0
Pulludown
CLK1
Pulludown
LE
0
1
Q0
nQ0
Q1
CLK_SEL
Pulludown
nQ1
Pin Assignment
V
EE
CLK_EN
CLK_SEL
CLK0
V
EE
CLK1
V
CC
1
2
3
4
5
6
7
14
13
12
11
10
9
8
V
CC
Q0
nQ0
nc
Q1
nQ1
V
CC
ICS8535I-21
14 Lead TSSOP
4.40mm x 5.0mm x 0.925mm package body
G Package
Top View
IDT™ / ICS™
3.3V LVPECL FANOUT BUFFER
1
ICS8535AGI-21 REV. A NOVEMBER 24, 2008
ICS8535I-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER
Table 1. Pin Descriptions
Number
1, 5
2
Name
V
EE
CLK_EN
Power
Input
Pullup
Type
Description
Negative supply pins.
Synchronizing clock enable. When HIGH, clock outputs follow clock input.
When LOW, Qx outputs are forced low, nQx outputs are forced high.
LVCMOS/LVTTL interface levels.
Clock select input. When HIGH, selects CLK1 input.
When LOW, selects CLK0 input. LVCMOS/LVTTL interface levels.
Single-ended clock inputs. LVCMOS/LVTTL interface levels.
Power supply pins.
Differential output pair. LVPECL interface levels.
No connect.
Differential output pair. LVPECL interface levels.
3
4, 6
7, 8, 14
9, 10
11
12, 13
CLK_SEL
CLK0, CLK1
V
CC
nQ1, Q1
nc
nQ0, Q0
Input
Input
Power
Output
Unused
Output
Pulldown
Pulldown
NOTE:
Pullup and Pulldown
refer to internal input resistors. See Table 2,
Pin Characteristics,
for typical values.
Table 2. Pin Characteristics
Symbol
C
IN
R
PULLUP
R
PULLDOWN
Parameter
Input Capacitance
Input Pullup Resistor
Input Pulldown Resistor
Test Conditions
Minimum
Typical
4
51
51
Maximum
Units
pF
k
Ω
k
Ω
IDT™ / ICS™
3.3V LVPECL FANOUT BUFFER
2
ICS8535AGI-21 REV. A NOVEMBER 24, 2008
ICS8535I-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER
Function Tables
Table 3A. Control Input Function Table
Inputs
CLK_EN
0
0
1
1
CLK_SEL
0
1
0
1
Selected Source
CLK0
CLK1
CLK0
CLK1
Q0, Q1
Disabled; Low
Disabled; Low
Enabled
Enabled
Outputs
nQ0, nQ1
Disabled; High
Disabled; High
Enabled
Enabled
After CLK_EN switches, the clock outputs are disabled or enabled following a rising and falling input clock edge as shown in Figure 1.
In the active mode, the state of the outputs are a function of the CLK0 and CLK1 inputs as described in Table 3B.
Disabled
Enabled
CLK0, CLK1
CLK_EN
nQ0, nQ1
Q0, Q1
Figure 1. CLK_EN Timing Diagram
Table 3B. Clock Input Function Table
Inputs
CLK0 or CLK1
0
1
Q0, Q1
LOW
HIGH
Outputs
nQ0, nQ1
HIGH
LOW
IDT™ / ICS™
3.3V LVPECL FANOUT BUFFER
3
ICS8535AGI-21 REV. A NOVEMBER 24, 2008
ICS8535I-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER
Absolute Maximum Ratings
NOTE: Stresses beyond those listed under
Absolute Maximum Ratings
may cause permanent damage to the device.
These ratings are stress specifications only. Functional operation of product at these conditions or any conditions beyond
those listed in the
DC Characteristics or AC Characteristics
is not implied. Exposure to absolute maximum rating conditions for
extended periods may affect product reliability.
Item
Supply Voltage, V
CC
Inputs, V
I
Outputs, I
O
Continuos Current
Surge Current
Package Thermal Impedance,
θ
JA
Storage Temperature, T
STG
Rating
4.6V
-0.5V to V
CC
+ 0.5V
50mA
100mA
103.8°C/W (0 mps)
-65°C to 150°C
DC Electrical Characteristics
Table 4A. Power Supply DC Characteristics,
V
CC
= 3.3V ± 5%, T
A
= -40°C to 85°C
Symbol
V
CC
I
EE
Parameter
Positive Supply Voltage
Power Supply Current
Test Conditions
Minimum
3.135
Typical
3.3
Maximum
3.465
50
Units
V
mA
Table 4B. LVCMOS/LVTTL DC Characteristics,
V
CC
= 3.3V ± 5%, T
A
= -40°C to 85°C
Symbol
V
IH
V
IL
Parameter
Input High Voltage
CLK0, CLK1
Input
Low Voltage
CLK_EN,
CLK_SEL
CLK0, CLK1,
CLK_SEL
CLK_EN
Input
Low Current
CLK0, CLK1,
CLK_SEL
CLK_EN
V
CC
= V
IN
= 3.465
V
CC
= V
IN
= 3.465
V
CC
= 3.465V, V
IN
= 0V
V
CC
= 3.465V, V
IN
= 0V
-5
-150
Test Conditions
Minimum
2
-0.3
-0.3
Typical
Maximum
V
CC
+ 0.3
1.3
0.8
150
5
Units
V
V
V
µA
µA
µA
µA
I
IH
Input
High Current
I
IL
IDT™ / ICS™
3.3V LVPECL FANOUT BUFFER
4
ICS8535AGI-21 REV. A NOVEMBER 24, 2008
ICS8535I-21
LOW SKEW, 1-TO-2 LVCMOS/LVTTL-TO-3.3V LVPECL FANOUT BUFFER
Table 4C. LVPECL DC Characteristics,
V
CC
= 3.3V ± 5%, T
A
= -40°C to 85°C
Symbol
V
OH
V
OL
V
SWING
Parameter
Output High Current; NOTE 1
Output Low Current; NOTE 1
Peak-to-Peak Output Voltage Swing
Test Conditions
Minimum
V
CC
– 1.4
V
CC
– 2.0
0.6
Typical
Maximum
V
CC
– 0.9
V
CC
– 1.7
1.0
Units
µA
µA
V
NOTE 1: Outputs termination with 50Ω to V
CC
– 2V.
AC Electrical Characteristics
Table 5. AC Characteristics,
V
CC
= 3.3V ± 5%, T
A
= -40°C to 85°C
Parameter Symbol
f
MAX
t
PD
tjit
tsk(o)
tsk(pp)
t
R
/ t
F
odc
Output Frequency
Propagation Delay; NOTE 1
Buffer Additive Phase Jitter, RMS;
refer to Additive Phase Jitter Section;
NOTE 2
Output Skew; NOTE 3, 4
Part-to-Part Skew; NOTE 4, 5
Output Rise/Fall Time
Output Duty Cycle
20% to 80% @ 50MHz
ƒ
≤
200MHz
300
45
ƒ
≤
266MHz
156.25MHz, Integration Range:
12kHz – 20MHz
1.0
0.03
20
300
600
55
Test Conditions
Minimum
Typical
Maximum
266
1.6
Units
MHz
ns
ps
ps
ps
ps
%
NOTE: Electrical parameters are guaranteed over the specified ambient operating temperature range, which is established when the
device is mounted in a test socket with maintained transverse airflow greater than 500 lfpm. The device will meet specifications after
thermal equilibrium has been reached under these conditions.
All parameters measured at ƒ
≤
266MHz unless noted otherwise.
NOTE 1: Measured from V
CC
/2 of the input to the differential output crossing point. The part does not add jitter.
NOTE 2: Driving only one input clock.
NOTE 3: Defined as skew between outputs at the same supply voltage and with equal load conditions.
Measured at V
CC
/2 of the input to the differential output crossing point.
NOTE 4: This parameter is defined in accordance with JEDEC Standard 65.
NOTE 5: Defined as skew between outputs on different devices operating at the same supply voltage and with equal load conditions.
Using the same type of inputs on each device, the outputs are measured at the differential cross points.
IDT™ / ICS™
3.3V LVPECL FANOUT BUFFER
5
ICS8535AGI-21 REV. A NOVEMBER 24, 2008
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