19-0724; Rev 0; 5/07
2.5Gbps PCI Express Passive Switches
General Description
The MAX4888/MAX4889 high-speed passive switches
route PCI Express
®
(PCIe) data between two possible
destinations. The MAX4888 is a quad single-pole/double-
throw (4 x SPDT) switch ideally suited for switching two
half lanes of PCIe data between two destinations. The
MAX4889 is an octal single-pole/double-throw (8 x SPDT)
switch ideal for switching four half lanes of PCIe data
between four destinations. The MAX4888/MAX4889 fea-
ture a single digital control input (SEL) to switch signal
paths.
The MAX4888/MAX4889 are fully specified to operate
from a single 3.0V to 3.6V power supply and also oper-
ate down to +1.65V. The MAX4888 is available
in a 3.5mm x 5.5mm, 28-pin TQFN package. The
MAX4889 is available in a 3.5mm x 9.0mm, 42-pin TQFN
package. Both devices operate over the -40°C to +85°C
temperature range.
o
Low Same-Pair Skew of 7ps
o
Low 120µA (Max) Quiescent Current
o
Supports PCIe Gen I Data Rates
o
Flow-Through Pin Configuration for Ease of
Layout
o
Industry-Compatible Pinout
o
Lead-Free Packaging
Features
o
Single 1.65V to 3.6V Power-Supply Voltage
MAX4888/MAX4889
Ordering Information/
Selector Guide
PART
PIN-
PACKAGE
CONFIGURATION
Two
Half Lanes
Four Half
Lanes
PKG
CODE
T283555-1
T423590M-1
Applications
Desktop Computers
Servers/Storage Area Networks
Laptops
MAX4888ETI+
28 TQFN-EP*
MAX4889ETO+
42 TQFN-EP*
PCI Express is a registered trademark of PCI-Sig Corp.
Note:
All devices are specified over the -40°C to +85°C operat-
ing temperature range.
+Denotes
lead-free package.
*EP
= Exposed paddle.
Typical Application Circuit appears at end of data sheet.
Pin Configurations
TOP VIEW
NC1+
NC2+
NO1+
NO2+
NC3+
NC4+
NO3+
NO4+
COM4-
NC1-
NC2-
NO1-
NO2-
NC3-
NC4-
NO3-
NC1+
NC2+
NO1+
NO2+
NC1-
NC2-
NO1-
NO2-
GND
NO4-
21 GND
20 V+
19 GND
18 V+
3
COM1-
4
GND
5
V+
6
COM2+
7
COM2-
8
V+
9
SEL
10 11 12 13 14 15 16 17
COM3+
COM3-
V+
COM4+
GND
GND
GND
V+
24 23 22 21 20 19 18 17 16 15
GND 25
V+ 26
GND 27
V+ 28
1
GND
*EP
+
2
SEL
3
N.C.
4
COM1+
5
COM1-
6
COM2+
7
COM2-
8
V+
9
N.C.
10
GND
14 GND
13 V+
GND 39
V+ 40
GND 41
V+ 42
38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22
MAX4888
12 GND
11 V+
MAX4889
*EP
+
1
GND
2
COM1+
TQFN
*CONNECT EXPOSED PADDLE TO GROUND.
TQFN
________________________________________________________________
Maxim Integrated Products
V+
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim's website at www.maxim-ic.com.
2.5Gbps PCI Express Passive Switches
MAX4888/MAX4889
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND, unless otherwise noted.)
V+ .............................................................................-0.3V to +4V
SEL, COM__, NO__, NC__ (Note 1) .............-0.3V to (V+ + 0.3V)
| COM__ - NO__ |, | COM__ - NC__ | (Note 1) ...................0 to 2V
Continuous Current (COM_ to NO__/NC__) .....................±70mA
Peak Current (COM__ to NO__/NC__)
(pulsed at 1ms, 10% duty cycle)..................................±70mA
Continuous Current (SEL).................................................±30mA
Peak Current (SEL)
(pulsed at 1ms, 10% duty cycle)................................±150mA
Continuous Power Dissipation (T
A
= +70°C)
28-Pin TQFN (derate 20.8mW/°C above +70°C) ....1666.7mW
42-Pin TQFN (derate 35.7mW/°C above +70°C) ....2857.1mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Junction Temperature ......................................................+150°C
Note 1:
Signals on SEL, NO__, NC__ or COM__ exceeding V+ or GND are clamped by internal diodes. Limit forward-diode current
to maximum current rating.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V+ = 3.0V to 3.6V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at V+ = 3.3V, T
A
= +25°C.) (Note 2)
PARAMETER
ANALOG SWITCH
Analog-Signal Range
V
COM_
,
V
NO_,
V
NC_
| V
COM_
-
V
NO_
| ,
| V
COM_
-
V
NC_
|
R
ON
ΔR
ON
ΔR
ON
R
FLAT(ON)
I
NO_(OFF)
I
NC_(OFF)
I
COM_(ON)
V+ = 3.0V, I
COM_
= 15mA,
V
NO_
or V
NC_
= 0V, 1.8V
V+ = 3.0V, I
COM_
= 15mA,
V
NO_
or V
NC_
= 0V (Notes 3, 4)
V+ = 3.0V, I
COM_
= 15mA,
V
NO_
or V
NC_
= 0V (Notes 3, 4)
V+ = 3.0V, I
COM_
= 15mA
V
NO_
or V
NC_
= 0V, 1.8V (Notes 4, 5)
V+ = 3.6V; V
COM_
= 0V, 1.8V;
V
NO_
or V
NC_
= 1.8V, 0V
V+ = 3.6V; V
COM_
= 0V, 1.8V;
V
NO_
or V
NC_
= V
COM_
or unconnected
-1
-1
-0.1
(V+ - 1.2)
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Voltage Between COM and
NO/NC
0
1.8
V
On-Resistance
On-Resistance Match Between
Pairs of Same Channel
On-Resistance Match
Between Channels
On-Resistance Flatness
NO_ or NC_ Off-Leakage
Current
COM_ On-Leakage
Current
7
0.1
0.6
0.06
1
2
2
+1
+1
Ω
Ω
Ω
Ω
µA
µA
2
_______________________________________________________________________________________
2.5Gbps PCI Express Passive Switches
MAX4888/MAX4889
ELECTRICAL CHARACTERISTICS (continued)
(V+ = 3.0V to 3.6V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at V+ = 3.3V, T
A
= +25°C.) (Note 2)
PARAMETER
DYNAMIC
Turn-On Time
Turn-Off Time
Propagation Delay
Output Skew Between Pairs
Output Skew Between Same
Pair
On-Loss
SYMBOL
t
ON
t
OFF
t
PD
t
SK1
t
SK2
CONDITIONS
V
NO_
or V
NC_
= 1.0V, R
L
= 50Ω, Figure 1
V
NO_
or V
NC_
= 1.0V, R
L
= 50Ω, Figure 1
R
S
= R
L
= 50Ω, unbalanced, Figure 2
R
S
= R
L
= 50Ω, unbalanced; skew between
any two pairs, Figure 2
R
S
= R
L
= 50Ω, unbalanced; skew between
two lines on same pair, Figure 2
R
S
= R
L
= 50Ω,
unbalanced,
Figure 3
Crosstalk between
any two pairs,
R
S
= R
L
= 50Ω,
unbalanced,
Figure 3
R
S
= R
L
= 50Ω
Signal = 0dBm,
R
S
= R
L
= 50Ω,
Figure 3
Figure 4
f = 10MHz
f = 1.25GHz
1MHz < f < 100MHz
500MHz < f < 1.25GHz
f = 50MHz
MIN
TYP
90
10
50
50
10
-0.5
dB
-1.4
-53
dB
f = 1.25GHz
-32
3.0
-56
dB
-26
1
2
0.5
1.4
100
V
SEL
= 0V or V+
-1
1.65
V
SEL
= 0V or V+
MAX4888
MAX4889
+1
3.60
60
120
pF
pF
V
V
mV
µA
V
µA
Gbps
MAX
250
50
UNITS
ns
ns
ps
ps
ps
G
LOS
Crosstalk
V
CT1
Signaling Data Rate
Off-Isolation
NO_/NC_ Off-Capacitance
COM_ On-Capacitance
LOGIC INPUT
Input-Logic Low
Input-Logic High
Input-Logic Hysteresis
Input Leakage Current
POWER SUPPLY
Power-Supply Range
V+ Supply Current
BR
V
ISO
C
NO_/NC_(OFF)
Figure 4
C
COM_(ON)
V
IL
V
IH
V
HYST
I
IN
V+
I+
Note 2:
All units are 100% production tested at T
A
= +85°C. Limits over the operating temperature range are guaranteed by design
and characterization and are not production tested.
Note 3:
ΔR
ON
= R
ON (MAX)
- R
ON (MIN)
.
Note 4:
Guaranteed by design. Not production tested.
Note 5:
Flatness is defined as the difference between the maximum and minimum value of on-resistance as measured over the
specified analog signal range.
_______________________________________________________________________________________
3
2.5Gbps PCI Express Passive Switches
MAX4888/MAX4889
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
ON-RESISTANCE vs. V
COM
(V+ = 1.8V)
MAX4888/89 toc01
MAX4888/89 toc02
ON-RESISTANCE vs. V
COM
10.0
9.5
9.0
8.5
R
ON
(Ω)
8.0
7.5
7.0
6.5
6.0
5.5
5.0
-0.1 0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1
V
COM
(V)
V+ = 3.3V
2
0
-0.1
0
V+ = 2.5V
R
ON
(Ω)
V+ = 1.8V
14
12
10
8
6
4
ON-RESISTANCE vs. V
COM
(V+ = 2.5V)
T
A
= +85°C
12
10
R
ON
(Ω)
8
6
4
2
0
T
A
= -40°C
T
A
= +25°C
MAX4888/89 toc03
14
T
A
= +85°C
T
A
= +25°C
T
A
= -40°C
0.1
0.2 0.3
V
COM
(V)
0.4
0.5
0.6
-0.1
0.1
0.3
0.5 0.7
V
COM
(V)
0.9
1.1
1.3
ON-RESISTANCE vs. V
COM
(V+ = 3.3V)
MAX4888/89 toc04
SUPPLY CURRENT vs. TEMPERATURE
(MAX4888)
70
SUPPLY CURRENT (μA)
60
V+ = 3.3V
50
40
30
20
10
0
-40
V+ = 1.8V
-15
10
35
TEMPERATURE (°C)
60
85
V+ = 2.5V
MAX4888/89 toc05
14
12
T
A
= +25°C
10
R
ON
(Ω)
8
6
4
2
0
T
A
= -40°C
T
A
= +85°C
80
-0.1 0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1
V
COM
(V)
4
_______________________________________________________________________________________
2.5Gbps PCI Express Passive Switches
Typical Operating Characteristics (continued)
(T
A
= +25°C, unless otherwise noted.)
EYE DIAGRAM
(V+ = 1.8V, f = 1.25GHz,
600mV
P-P
PRBS SIGNAL, R
S
= R
L
= 50Ω)
†
V
COM_+
MAX4888/89 toc08
MAX4888/MAX4889
LOGIC THRESHOLD vs. SUPPLY VOLTAGE
MAX4888/89 toc06
TURN-ON/-OFF TIME vs. SUPPLY VOLTAGE
240
220
200
180
160
t
ON
/t
OFF
(ns)
140
120
100
80
60
40
20
0
MAX4888/89 toc07
1.2
1.1
LOGIC THRESHOLD (V)
1.0
0.9
0.8
V
IL
0.7
0.6
0.5
V
IH
NO_ t
ON
50mV/div
NC_ t
ON
NO_ t
OFF
NC_ t
OFF
V
COM_-
1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6
SUPPLY VOLTAGE (V)
50ps/div
*PRBS = PSEUDORANDOM BIT SEQUENCE
†
GEN I; 2.5Gps; UI = 400ps
1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6
SUPPLY VOLTAGE (V)
EYE DIAGRAM
(V+ = 2.5V, f = 1.25GHz,
600mV
P-P
PRBS SIGNAL, R
S
= R
L
= 50Ω)
†
MAX4888/89 toc09
EYE DIAGRAM
(V+ = 3.3V, f = 1.25GHz,
600mV
P-P
PRBS SIGNAL, R
S
= R
L
= 50Ω)
†
V
COM_+
MAX4888/89 toc10
V
COM_+
50mV/div
50mV/div
V
COM_-
50ps/div
*PRBS = PSEUDORANDOM BIT SEQUENCE
†
GEN I; 2.5Gps; UI = 400ps
V
COM_-
50ps/div
*PRBS = PSEUDORANDOM BIT SEQUENCE
†
GEN I; 2.5Gps; UI = 400ps
_______________________________________________________________________________________
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