SY89473U
Precision LVPECL 2:1 Multiplexer with 1:2
Fanout and Internal Termination
Precision Edge is a registered trademark of Micrel, Inc.
MLF and
Micro
LeadFrame are trademarks of Amkor Technology, Inc.
Micrel Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel +1 (408) 944-0800 fax + 1 (408) 474-1000 http://www.micrel.com
May 2005
M9999-052405
hbwhelp@micrel.com
or (408) 955-1690
General Description
The SY89473U is a 2.5V/3.3V precision, high-speed 2:1
differential MUX capable of processing clocks up to
2.5GHz and data up to 2.5Gbps.
The differential input includes Micrel's unique, 3-pin
input termination architecture that directly interfaces to
any differential signal (AC- or DC-coupled) as small as
100mV (200mV
PP
) without any level shifting or
termination resistor networks in the signal path. The
output is 800mV, 100K-compatible, LVPECL with fast
rise/fall times guaranteed to be less than 190ps.
The SY89473U operates from a 2.5V 5% or 3.3V
10% supply and is guaranteed over the full industrial
temperature range of 40C to +85C. The SY89473U is
part of Micrel's high-speed, Precision Edge
product
line. For multiple-clock switchover solutions, please refer
to the SY89840SY89843U family.
All support documentation can be found on Micrel's web
site at:
www.micrel.com
.
Functional Block Diagram
Precision Edge
Features
Selects between two input channels and provides two
copies of the selected output
Guaranteed AC performance over temperature and
supply voltage:
- DC to 2.5Gbps data throughput
- DC to 2.5GHz f
MAX
(clock)
- <500ps In-to-Out t
pd
- <190ps t
r
/t
f
- <20ps Output-to-output skew
Unique patented input isolation design minimizes
crosstalk
Ultra-low Jitter Design:
- <1ps
RMS
random jitter
- <1ps
RMS
cycle-to-cycle jitter
- <10ps
PP
total jitter (clock)
- <0.7ps
RMS
crosstalk induced jitter
Unique patent-pending input termination and VT pin
accepts DC- and AC-coupled inputs (CML, PECL,
LVDS)
800mV (100K) LVPECL output swing
2.5V 5% or 3.3V 10% supply voltage
-40C to +85C industrial temperature range
Available in 24-pin (4mm x 4mm) MLF
TM
package
Applications
Clock switchover
Data distribution
Markets
LAN/WAN
Enterprise servers
ATE
Test and measurement
Micrel, Inc.
SY89473U
May 4, 2005
2
M9999-050405
hbwhelp@micrel.com
or (408) 955-1690
Ordering Information
(1)
Part Number
Package Type
Operating
Range
Package Marking
Lead
Finish
SY89473UMG
MLF-24
Industrial
SY89473U with Pb-Free bar-line indicator
NiPdAu
Pb-Free
SY89473UMGTR
(2)
MLF-24
Industrial
SY89473U with Pb-Free bar-line indicator
NiPdAu
Pb-Free
Notes:
1. Contact factory for die availability. Dice are guaranteed at T
A
= 25C, DC Electricals Only.
2. Tape
and
Reel.
Pin Configuration
24-Pin MLF
TM
(MLF-24)
Micrel, Inc.
SY89473U
May 2005
3
M9999-052405
hbwhelp@micrel.com
or (408) 955-1690
Pin Description
Pin Number
Pin Name
Pin Function
5, 2,
23, 20
IN0, /IN0
IN1, /IN1
Differential Inputs: These input pairs are the differential signal inputs to the device.
They accept AC or DC-coupled signals as small as 100mV (200mV
PP
). Note that
these inputs will default to an indeterminate state if left open. Each pin of a pair
internally terminates to a VT
pin through 50. Please refer to the "Input Interface
Applications" section for more details.
3, 21
VREF-AC0
,
VREF-AC1
Reference Voltage: These outputs bias to V
CC
-1.2V. They are used for AC-
coupling inputs IN and /IN. Connect VREF-AC directly to the corresponding VT pin.
Bypass with 0.01F low ESR capacitor to VCC. Maximum sink/source current is
1.5mA. Due to the limited drive capability, the VREF-AC pin is only intended to
drive its respective VT pin. Please refer to the "Input Interface Applications" section
for more details.
4, 22
VT0
,
VT1
Input Termination Center-Tap: Each side of the differential input pair terminates to
a VT
pin. The VT0 and VT1 pins provide a center-tap to a termination network for
maximum interface flexibility. Please refer to the "Input Interface Applications"
section for more details.
1, 6, 9, 10, 13,
19, 24
VCC
Positive Power Supply: Connect to +2.5V or +3.3V power supply. Bypass with
0.1F//0.01F low ESR capacitors as close to VCC pins as possible.
7, 8
11, 12
Q0, /Q0
Q1, /Q1
Differential Outputs: These differential LVPECL output pairs are a logic function of
the IN0, IN1, and SEL inputs. Please refer to the truth table below for details.
Unused output pairs can be left floating with no impact on jitter.
15 SEL
This single-ended TTL/CMOS-compatible input selects the inputs to the
multiplexer. Note that this input is internally connected to a 25k pull-up resistor
and will default to a logic HIGH state if left open. V
TH
= V
CC
/2. Please refer to the
"Timing Diagram" section for more details.
14, 17, 18
GND, Exposed
Pad
Ground: Ground pins and exposed pad must be connected to the same ground
plane.
Truth Table
INPUTS OUTPUTS
IN0 /IN0 IN1 /IN1 SEL Q /Q
0 1 X X 0 0
1
1 0 X X 0 1
0
X X 0 1 1 0 1
X X 1 0 1 1 0
Micrel, Inc.
SY89473U
May 2005
4
M9999-052405
hbwhelp@micrel.com
or (408) 955-1690
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
Input Current
Source/sink
Current on IN, /IN..............................50mA
Source/sink Current on V
T
..................................100mA
V
REF-AC
Current
Source/sink Current on V
REF-AC
...............................2mA
Lead Temperature (soldering, 20 sec.) ...................+260C
Storage Temperature (T
S
) ...........................-65C to 150
C
Operating Ratings
(2)
Supply Voltage (V
CC
) .................................. +2.375V to +2.625V
....................................................................+3.0V
to +3.6V
Ambient Temperature (T
A
).................................40C to +85C
Package Thermal Resistance
(3)
MLFTM
(
JA
)
Still-Air.................................................................... 50C/W
MLFTM (
JB
)
Junction-to-Board ................................................... 30C/W
DC Electrical Characteristics
(4)
T
A
= 40C to +85C; unless otherwise stated.
Symbol Parameter
Condition
Min
Typ
Max
Units
2.375 2.5 2.625 V
V
CC
Power
Supply
3.0 3.3 3.6 V
I
CC
Power Supply Current
No load, max V
CC
.
45
65
mA
R
IN
Input Resistance
(IN-to-V
T
)
45
50
55
R
DIFF_IN
Differential Input Resistance
(IN-to-/IN)
90
100
110
V
IH
Input High Voltage
(IN, /IN)
1.2
V
CC
V
V
IL
Input Low Voltage
(IN, /IN)
0
V
IH
-0.1 V
V
IN
Input Voltage Swing
(IN, /IN)
See Figure 1a. Note 5
0.1
V
CC
V
V
DIFF_IN
Differential Input Voltage Swing
|IN-/IN|
See Figure 1b.
0.2
V
V
T_IN
IN-to-V
T
(IN, /IN)
1.
28
V
V
REF-AC
Output Reference Voltage
V
CC
-1.3 V
CC
-1.2 V
CC
-1.1 V
Notes:
1. Permanent device damage may occur if 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. Package thermal resistance assumes exposed pad is soldered (or equivalent) to the devices most negative potential on the PCB.
JA
and
JB
values are determined for a 4-layer board in still air unless otherwise stated.
4. The circuit is designed to meet the DC specifications shown in the above table after thermal equilibrium has been established.
5. V
IN
(max) is specified when V
T
is floating.
Micrel, Inc.
SY89473U
May 2005
5
M9999-052405
hbwhelp@micrel.com
or (408) 955-1690
LVPECL Outputs DC Electrical Characteristics
(6)
V
CC
= 2.5V 5% or 3.3V 10%; T
A
= -40C to + 85C; R
L
= 50 to V
CC
-2V, unless otherwise stated.
Symbol Parameter
Condition
Min
Typ
Max
Units
V
OH
Output HIGH Voltage
Q, /Q
V
CC
1.145 V
CC
-0.895 V
V
OL
Output LOW Voltage
Q, /Q
V
CC
1.945 V
CC
-1.695 V
V
OUT
Output Voltage Swing
Q, /Q
See Figure 1a.
550
800
mV
V
DIFF-OUT
Differential Output Voltage Swing
Q, /Q
See Figure 1b.
1100
1600
mV
LVTTL/CMOS DC Electrical Characteristics
(6)
V
CC
= 2.5V 5% or 3.3V 10%; T
A
= -40C to + 85C, unless otherwise stated.
Symbol Parameter
Condition
Min
Typ
Max
Units
V
IH
Input HIGH Voltage
2.0
V
V
IL
Input LOW Voltage
0.8
V
I
IH
Input HIGH Current
-125
30
A
I
IL
Input LOW Current
-300
A
Note:
6.
The circuit is designed to meet the DC specifications shown in the above table after thermal equilibrium has been established.
PDF 
ZIP