2.5V LVDS, 1:4 GLITCHLESS CLOCK BUFFER
TERABUFFER™ II
General
Description
The IDT5T93GL04 2.5V differential clock buffer is a
user-selectable differential input to four LVDS outputs. The fanout
from a differential input to four LVDS outputs reduces loading on
the preceding driver and provides an efficient clock distribution
network. The IDT5T93GL04 can act as a translator from a
differential HSTL, eHSTL, LVEPECL (2.5V), LVPECL (3.3V),
CML, or LVDS input to LVDS outputs. A single-ended 3.3V / 2.5V
LVTTL input can also be used to translate to LVDS outputs. The
redundant input capability allows for
a
glitchless change-over from
a primary clock source to a secondary clock source up to 450MHz.
Selectable inputs are controlled by SEL. During the switchover,
the output will disable low for up to three clock cycles of the
previously-selected input clock. The outputs will remain low for up
to three clock cycles of the newly-selected clock, after which the
outputs will start from the newly-selected input. A FSEL pin has
been implemented to control the switchover in cases where a
clock source is absent or is driven to DC levels below the minimum
specifications.
The IDT5T9304 outputs can be asynchronously enabled/disabled.
When disabled, the outputs will drive to the value selected by the
GL pin. Multiple power and grounds reduce noise.
IDT5T93GL04
Features
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Guaranteed low skew: <50ps (maximum)
Very low duty cycle distortion: <100ps (maximum
High speed propagation delay: <2.2ns (maximum)
Up to 450MHz operation
Selectable inputs
Hot insertable and over-voltage tolerant inputs
3.3V/2.5V LVTTL, HSTL, eHSTL, LVEPECL (2.5V), LVPECL
(3.3V), CML or LVDS input interface
Selectable differential inputs to four LVDS outputs
Power-down mode
At power-up, FSEL should be LOW
2.5V V
DD
-40°C to 85°C ambient operating temperature
Available in TSSOP package
Applications
•
Clock distribution
Pin Assignment
GND
PD
FSEL
V
DD
Q1
Q1
Q2
Q2
V
DD
SEL
G
GND
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
A2
A2
GND
V
DD
Q3
Q3
Q4
Q4
V
DD
GL
A1
A1
24-Lead TSSOP
4.4mm x 7.8mm x 1.0mm package body
G Package
Top View
IDT™ LVDS GLITCHLESS CLOCK BUFFER TERABUFFER™ II
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IDT5T93GL04 REV. A JULY 10, 2007
IDT5T93GL04
2.5V LVDS 1:4 GLITCHLESS CLOCK BUFFER TERABUFFER™ II
Block Diagram
GL
G
OUTPUT
CONTROL
Q1
Q1
PD
OUTPUT
CONTROL
Q2
Q2
A1
A1
1
OUTPUT
CONTROL
Q3
Q3
A2
A2
0
OUTPUT
CONTROL
Q4
Q4
SEL
FSEL
IDT™ LVDS GLITCHLESS CLOCK BUFFER TERABUFFER™ II
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IDT5T93GL04 REV. A JULY 10, 2007
IDT5T93GL04
2.5V LVDS 1:4 GLITCHLESS CLOCK BUFFER TERABUFFER™ II
Table 1. Pin Descriptions
Name
A[1:2]
Input
Type
Description
Adjustable
(1, 4)
Clock input. A
[1:2]
is the "true" side of the differential clock input.
Complementary clock inputs. A[1:2] is the complementary side of A[1:2]
.
For LVTTL single-ended operation, A[1:2] should be set to the desired toggle
(1, 4)
voltage for A[1:2]:
Adjustable
3.3V LVTTL V
REF
= 1650mV
2.5V LVTTL V
REF
= 1250mV
LVTTL
Gate control for differential outputs Q1 and Q1 through Q4 and Q4. When G is
LOW, the differential outputs are active. When G is HIGH, the differential
outputs are asynchronously driven to the level designated by GL
(2)
.
Specifies output disable level. If HIGH, "true" outputs disable HIGH and
"complementary" outputs disable LOW. If LOW, "true" outputs disable LOW
and "complementary" outputs disable HIGH.
Clock outputs.
Complementary clock outputs.
Reference clock select. When LOW, selects A2 and A2.
When HIGH, selects A1 and A1.
Power-down control. Shuts off entire chip. If LOW, the device goes into low
power mode. Inputs and outputs are disabled. Both "true" and
"complementary" outputs will pull to V
DD
. Set HIGH for normal operation.
(3)
At a rising edge, FSEL forces select to the input designated by SEL.
Set LOW for normal operation. At power-up, FSEL should be LOW.
Power supply for the device core and inputs.
Ground.
A[1:2]
Input
G
Input
GL
Q[1:2]
Q{1:2}
SEL
Input
Output
Output
Input
LVTTL
LVDS
LVDS
LVTTL
PD
Input
LVTTL
FSEL
V
DD
GND
Input
LVTTL
Power
Power
NOTES:
1.
Inputs are capable of translating the following interface standards:
Single-ended 3.3V and 2.5V LVTTL levels
Differential HSTL and eHSTL levels
Differential LVEPECL (2.5V) and LVPECL (3.3V) levels
Differential LVDS levels
Differential CML levels
2.
Because the gate controls are asynchronous, runt pulses are possible. It is the user's responsibility to either time the gate control
signals to minimize the possibility of runt pulses or be able to tolerate them in down stream circuitry.
3.
It is recommended that the outputs be disabled before entering power-down mode. It is also recommended that the outputs remain
disabled until the device completes power-up after asserting PD.
4.
The user must take precautions with any differential input interface standard being used in order to prevent instability when there is
no input signal.
Table 2. Pin Characteristics
(T
A
= +25°C, F = 1.0MHz)
Symbol
C
IN
Parameter
Input Capacitance
Test Conditions
Minimum
Typical
Maximum
3
Units
pF
NOTE: This parameter is measured at characterization but not tested.
IDT™ LVDS GLITCHLESS CLOCK BUFFER TERABUFFER™ II
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IDT5T93GL04 REV. A JULY 10, 2007
IDT5T93GL04
2.5V LVDS 1:4 GLITCHLESS CLOCK BUFFER TERABUFFER™ II
Function Tables
Table 3A. Gate Control Output Table
Codntrol Output
GL
0
0
1
1
G
0
1
0
1
Q[1:4]
Toggling
LOW
Toggling
HIGH
Outputs
Q[1:4]
Toggling
HIGH
Toggling
LOW
Table 3B. Input Selection Table
Selection SEL pin
0
1
Inputs
A2/A2
A1/A1
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 Characterisitcs
is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
product reliability..
Item
Power Supply Voltage, V
DD
Input Voltage, V
I
Output Voltage, V
O
Not to exceed 3.6V
Storage Temperature, T
STG
Junction Temperature, T
J
Rating
-0.5V to +3.6V
-0.5V to +3.6V
-0.5 to V
DD
+0.5V
-65°C to 150°C
150°C
Recommended Operating Range
Symbol
T
A
V
DD
Description
Ambient Operating Temperature
Internal Power Supply Voltage
Minimum
-40
2.3
Typical
+25
2.5
Maximum
+85
2.7
Units
°C
V
IDT™ LVDS GLITCHLESS CLOCK BUFFER TERABUFFER™ II
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IDT5T93GL04 REV. A JULY 10, 2007
IDT5T93GL04
2.5V LVDS 1:4 GLITCHLESS CLOCK BUFFER TERABUFFER™ II
DC Electrical Characteristics
Table 4A. LVDS Power Supply DC Characteristics
(1)
,
T
A
= -40°C to 85°C
Symbol
I
DDQ
I
TOT
I
PD
Parameter
Quiescent V
DD
Power Supply Current
Total Power
V
DD
Supply Current
Total Power Down
Supply Current
Test Conditions
V
DD
= Max.,
All Input Clocks = LOW
(2)
; Outputs enabled
V
DD
= 2.7V;
F
REFERENCE
Clock = 450MHz
PD = LOW
Minimum
Typical
(2)
Maximum
240
250
5
Units
mA
mA
mA
NOTE 1: These power consumption characteristics are for all the valid input interfaces and cover the worst case conditions.
NOTE 2: The true input is held LOW and the complementary input is held HIGH.
Table 4B. LVTTL DC Characteristics
(1)
,
T
A
= -40°C to 85°C
Symbol
I
IH
I
IL
V
IK
V
IN
V
IH
V
IL
V
THI
V
REF
Parameter
Input High Current
Input Low Current
Clamp Diode Voltage
DC Input Voltage
DC Input High Voltage
DC Input Low Voltage
DC Input Threshold Crossing Voltage
Single-Ended Reference Voltage
(3)
3.3V LVTTL
2.5V LVTTL
V
DD
/2
1.65
1.25
Test Conditions
V
DD
= 2.7V
V
DD
= 2.7V
V
DD
= 2.3V, I
IN
= -18mA
-0.3
1.7
0.7
-0.7
Minimum
Typical
(2)
Maximum
±5
±5
-1.2
3.6
Units
µA
µA
V
V
V
V
V
V
V
NOTE 1: See
Recommended Operating Range
table.
NOTE 2: Typical values are at V
DD
= 2.5V, +25°C ambient.
NOTE 3: For A[1:2] single-ended operation, A[1:2] is tied to a DC reference voltage.
Table 4C. Differential DC Characteristics
(1)
,
T
A
= -40°C to 85°C
Symbol
I
IH
I
IL
V
IK
V
IN
V
DIF
V
CM
Parameter
Input High Current
Input Low Current
Clamp Diode Voltage
DC Input Voltage
DC Differential Voltage
(3)
DC Common Mode Input Voltage
Test Conditions
V
DD
= = 2.7V
V
DD
= = 2.7V
V
DD
= 2.3V, I
IN
= -18mA
-0.3
0.1
0.05
V
DD
-0.7
Minimum
Typical
(2)
Maximum
±5
±5
-1.2
3.6
Units
µA
µA
V
V
V
V
NOTE 1: See
Recommended Operating Range
table.
NOTE 2: V
DIF
specifies the minimum input differential voltage (V
TR
- V
CP
) required for switching where V
TR
is the "true" input level and
V
CP
is the "complement" input level. The DC differential voltage must be maintained to guarantee retaining the existing HIGH or LOW
input. The AC differential voltage must be achieved to guarantee switching to a new state.
NOTE 3: V
CM
specifies the maximum allowable range of (V
TR
+ V
CP
) /2.
NOTE 4: Typical values are at V
DD
= 2.5V, +25°C ambient.
IDT™ LVDS GLITCHLESS CLOCK BUFFER TERABUFFER™ II
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IDT5T93GL04 REV. A JULY 10, 2007
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