SY89854U
Precision Low Power 1:4 LVPECL Fanout
Buffer/Translator with Internal Termination
General Description
The SY89854U is a 2.5V/3.3V precision, high-
speed, fully differential 1:4 LVPECL fanout buffer.
Optimized to provide four identical output copies
with less than 20ps of skew and less than 10ps
(pp)
total jitter, the SY89854U can process clock signals
as fast as 2GHz.
The differential input includes Micrel’s unique, patent
pending 3-pin input termination architecture that
interfaces to any differential signal (AC or DC-
coupled) as small as 100mV (200mVpp) without any
level shifting or termination resistor networks in the
signal path. For AC-coupled input interface
applications, an on-board output reference voltage
(VREF-AC) is provided to bias the center-tap (VT)
pin. The outputs are 800mV LVPECL, with fast
rise/fall times guaranteed to be less than 180ps.
The SY89854U operates from a 2.5V ±5% supply or
a 3.3V ±10% supply and is guaranteed over the full
industrial temperature range of –40°C to +85°C.
The SY89854U is part of Micrel’s high-speed,
®
Precision Edge product line.
All support documentation can be found on Micrel’s
web site at:
www.micrel.com.
Precision Edge
®
Features
•
Precision 1:4, LVPECL fanout buffer
•
Low power: 137mW (2.5V typ)
•
Guaranteed AC performance over temperature
and supply voltage:
– DC- to > 2GHz Clock f
MAX
– <340ps t
pd
– <180ps t
r
/t
f
time
– <20ps max. skew
•
Ultra-low jitter design:
– <1ps
(rms)
random jitter
– <10ps
(pp)
deterministic jitter
– <10ps
(pp)
total jitter (clock)
•
Unique patent pending input termination and VT
pin accepts DC-coupled and AC-coupled inputs
(CML, PECL, LVDS)
•
Typical 800mV (100k) LVPECL output swing
•
Power supply 2.5V ±5% or 3.3V ±10%
•
Industrial temperature range –40°C to +85°C
•
Available in ultra-small (3mm x 3mm) 16-pin QFN
package
Typical Applications
200MHz (Q - /Q)
Applications
•
SONET and All GigE clock distribution
•
Fibre Channel clock and data distribution
•
Backplane distribution
Output Swing
(200mV/di
v.)
TIME (600ps/di
v.)
United States Patent No. RE44,134
Precision Edge is a registered trademark of Micrel, Inc.
August 2007
M9999-082907-C
hbwhelp@micrel.com
or (408) 955-1690
Micrel, Inc.
SY89854U
Ordering Information
(1)
Part Number
SY89854UMG
SY89854UMGTR
Notes:
1. Contact factory for die availability. Dice are guaranteed at T
A
= 25°C, DC Electricals Only.
2. Tape and Reel.
(2)
Package Type
QFN-16
QFN-16
Operating
Range
Industrial
Industrial
Package Marking
854U with Pb-free bar-line indicator
854U with Pb-free bar-line indicator
Lead
Finish
Pb-Free
NiPdAu
Pb-Free
NiPdAu
Pin Configuration
16-Pin QFN
Pin Description
Pin Number
Pin Name
Pin Function
Differential Input: This input pair is the signal to be buffered. These inputs accept
AC- or DC-coupled differential signals as small as 100mV (200mV
PP
). Each pin
of this pair internally terminates to a VT pin through 50Ω.
Note that this input will
default to an indeterminate state if left open. Please refer to the “Input Interface
Applications” section for more details.
Input Termination Center-Tap: Each side of the differential input pair terminates
to this pin. The VT pin provides a center-tap to a termination network for
maximum interface flexibility. See “Input Interface Applications” section for more
details.
Positive Power Supply. Bypass with 0.1µF||0.01µF low ESR capacitors as close
to the VCC pin as possible.
Differential 100K LVPECL Output: These LVPECL outputs are the precision, low
skew copies of the input signal. Terminate with 50Ω
to V
CC
–2V. Unused output
pairs may be left floating with no impact on jitter. See “Output Interface
Applications” section.
Ground. Ground pin and exposed pad must be connected to the same ground
plane.
Reference Voltage: This output biases to V
CC
–1.2V. It is used when AC coupling
the inputs (IN, /IN). Connect V
REF-AC
to the VT pin. Bypass VREF-AF pin with a
0.01µF low ESR capacitor to V
CC
. Maximum sink/source capability is 1.5mA. See
“Input Interface Applications” section for more details.
1, 4
IN, /IN
2
VT
8,13
15, 14
12, 11
10, 9
7, 6
5, 16
VCC
Q0, /Q0
Q1, /Q1
Q2, /Q2
Q3, /Q3
GND,
Exposed Pad
VREF-AC
3
August 2007
2
M9999-082907-C
hbwhelp@micrel.com
or (408) 955-1690
Micrel, Inc.
SY89854U
Functional Block Diagram
August 2007
3
M9999-082907-C
hbwhelp@micrel.com
or (408) 955-1690
Micrel, Inc.
SY89854U
Absolute Maximum Ratings
(1)
Supply Voltage (V
CC
) .......................... –0.5V to +4.0V
Input Voltage (V
IN
) ..................................–0.5V to V
CC
LVPECL Output Current (I
OUT
)
Continuous ................................................. 50mA
Surge ........................................................ 100mA
(3)
Termination Current
Source or sink current on V
T
.................... ±50mA
Input Current
Source or sink current on IN, /IN .............. ±50mA
(3)
VREF-AC Current
Source or sink current ................................ ±2mA
Lead Temperature (soldering, 20sec.) ........... +260°C
Storage Temperature (T
s
) ..................–65°C to 150°C
Operating Ratings
(2)
Supply Voltage (V
CC
).................. +2.375V to +2.625V
......................................................+3.0V to +3.6V
Ambient Temperature (T
A
) ................ –40°C to +85°C
(4)
Package Thermal Resistance
QFN (θ
JA
)
Still-Air ..................................................... 60°C/W
QFN (ψ
JB
)
Junction-to-Board .................................... 38°C/W
DC Electrical Characteristics
(5)
T
A
= –40°C to +85°C, unless otherwise stated.
Symbol
V
CC
I
CC
R
DIFF_IN
R
IN
V
IH
V
IL
V
IN
V
DIFF_IN
V
T_IN
Notes:
1. Permanent device damage may occur if the Absolute Maximum Ratings are exceeded. This is a stress rating only and functional operation
is not implied at conditions other than those detailed in the operational sections of this data sheet. Exposure to Absolute Maximum Ratings
conditions for extended periods may affect device reliability.
2. The data sheet limits are not guaranteed if the device is operated beyond the operating ratings.
3. Due to the limited drive capability use for input of the same package only.
4. Package thermal resistance assumes exposed pad is soldered (or equivalent) to the devices most negative potential on the PCB.
θ
JA
and
ψ
JB
are calculated based on a 4-layer board in still air, unless otherwise stated.
5. The circuit is designed to meet the DC specifications shown in the above table after thermal equilibrium has been established.\
6. V
IH
(min) not lower than 1.2V.
Parameter
Power Supply
Power Supply Current
Differential Input Resistance
(IN, /IN)
Input Resistance
(IN-to-V
T
)
Input High Voltage
(IN, /IN)
Input Low Voltage
(IN, /IN)
Input Voltage Swing
(IN, /IN)
Differential Input Voltage Swing
(IN, /IN)
IN-to-V
T
Condition
Min
2.375
3.0
Typ
2.5
3.3
55
Max
2.625
3.6
78
110
55
V
CC
V
IH
–0.1
1.7
Units
V
V
mA
Ω
Ω
V
V
V
V
No load, max. V
CC
90
45
Note 6
V
CC
–1.6
0
See Figure 1a.
See Figure 1b.
0.1
0.2
100
50
1.28
V
August 2007
4
M9999-082907-C
hbwhelp@micrel.com
or (408) 955-1690
Micrel, Inc.
SY89854U
LVPECL Outputs DC Electrical Characteristics
(7)
V
CC
= +2.5V ±5% or +3.3V ±10%; T
A
= –40°C to + 85°C; R
L
= 50Ω
to V
CC
–2V, unless otherwise stated.
Symbol
V
OH
V
OL
V
OUT
V
DIFF-OUT
Note:
7. The circuit is designed to meet the DC specifications shown in the above table after thermal equilibrium has been established.
Parameter
Output HIGH Voltage
Q, /Q
Output LOW Voltage
Q, /Q
Output Voltage Swing
Q, /Q
Differential Output Voltage Swing
Q,/Q
Condition
Min
V
CC
–1.145
V
CC
–1.945
Typ
Max
V
CC
–0.895
V
CC
–1.695
Units
V
V
mV
mV
See Figure 1a.
See Figure 1b.
550
1100
800
1600
August 2007
5
M9999-082907-C
hbwhelp@micrel.com
or (408) 955-1690
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