MAX4890 Maxim, MAX4890 Datasheet - Page 10

• Manufacturer Part Number: MAX4890
• Description: The MAX4890/MAX4891/MAX4892 high-speed analog switches meet the needs of 10/100/1000 Base-T applications
• Manufacturer: Maxim

10/100/1000 Base-T Ethernet LAN Switch
The on-resistance of the MAX4890/MAX4891/MAX4892
is very low and stable as the analog input signals are
swept from ground to V+ (see the Typical Operating
Characteristics ). The switches are bidirectional, allow-
ing A_ and _B_ to be configured as either inputs or out-
puts.
The MAX4890/MAX4891/MAX4892 are characterized
using the Human Body Model for ±2kV of ESD protec-
tion. Figure 8 shows the Human Body Model, and Figure
9 shows the current waveform the Human Body Model
generates when discharged into a low-impedance load.
This model consists of a 100pF capacitor charged to the
ESD voltage of interest, which is then discharged into the
test device through a 1.5kΩ resistor.
The Typical Operating Circuit depicts the MAX4890/
MAX4891/MAX4892 in a 10/100/1000 Base-T docking
station application.
Figure 4. Differential Crosstalk
10
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Applications Information
Typical Operating Circuit
ANALYZER
ANALYZER
NETWORK
NETWORK
DIFFERENTIAL CROSSTALK RECEIVE CKT
DIFFERENTIAL CROSSTALK TRANSMIT CKT
Analog Signal Levels
ESD Protection
50Ω
TRACE
50Ω
TRACE
1
3
1
3
MINI CKT
MINI CKT
50:100
BALUN
BALUN
50:100
6
4
6
5
4
CB4
CB5
TRACE
50Ω
TRACE
50Ω
Figure 10 shows the MAX4890/MAX4891/MAX4892 in a
line-card redundancy configuration.
Caution: Do not exceed the absolute maximum ratings.
Stresses beyond the listed ratings may cause perma-
nent damage to the device.
Proper power-supply sequencing is recommended for
all CMOS devices. Always apply V+ before applying
analog signals, especially if the analog signal is not
current limited.
High-speed switches require proper layout and design
procedures for optimum performance. Keep design-
controlled-impedance printed circuit board traces as
short as possible. Ensure that bypass capacitors are as
close to the device as possible. Use large ground
planes where possible.
A6
9
A7
10
A5
A4
8
7
MAX4892
36-TQFN
Line-Card Redundancy (Ethernet T3/E3)
5B1
AB1
6B1
7B1
21
22
18
17
Power-Supply Sequencing and
49.9Ω
49.9Ω
49.9Ω
49.9Ω
R3
R3
R4
R4
Overvoltage Protection
Layout