19-2141; Rev 0; 8/01
75Ω/100Ω/120Ω Switchable Termination
Networks
General Description
The MAX3406/MAX3407/MAX3408 are general-purpose
line-terminating networks designed to change the termi-
nation value of a line, depending on the state of a digi-
tal control line, allowing the connection to a coaxial
cable or a twisted pair wire. These devices are switch-
able between 75Ω, 100Ω, and 120Ω. The MAX3406
can switch from 75Ω to 100Ω, the MAX3407 can switch
from 75Ω to 120Ω, and the MAX3408 can switch from
100Ω to 120Ω termination. Termination resistance val-
ues are guaranteed to ±2.5% through -40°C to +85°C
and for signal levels of ±3.6V.
The MAX3406/MAX3407/MAX3408 consume only 50µA
supply current and are fully specified for operation from
a +4.5V to +5.5V power supply. These devices are avail-
able in a tiny 5-pin SOT23 package. All specifications
are guaranteed over the extended temperature range of
-40°C to +85°C.
o
Available in 5-Pin SOT Package
o
±2.5% Resistance Accuracy Over Extended
Temperature Range
o
-3.6V to +3.6V Input Voltage Range
o
50µA Supply Current (max)
o
Bipolar Input Range Off a Single Supply
o
Switchable Termination
75Ω or 100Ω (MAX3406)
75Ω or 120Ω (MAX3407)
100Ω or 120Ω (MAX3408)
Features
MAX3406/MAX3407/MAX3408
Applications
Telecom E1/T1/J1 Coax/Twisted Pair Termination
Data Routers
Telecom Racks
Video Security
Industrial Networks
Ethernet Networks
PART
MAX3406EUK
MAX3407EUK
MAX3408EUK
Ordering Information
TEMP.
RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-
PACKAGE
5 SOT23-5
5 SOT23-5
5 SOT23-5
TOP
MARK
ADSV
ADSW
ADSX
Pin Configuration
TOP VIEW
PART
V
CC
1
5
A
Selector Guide
TERMINATION
ENABLE = 1
MAX3406EUK
MAX3407EUK
MAX3408EUK
75Ω
75Ω
100Ω
ENABLE = 0
100Ω
120Ω
120Ω
GND
2
MAX3406
MAX3407
MAX3408
4
B
ENABLE
3
SOT23-5
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
75Ω/100Ω/120Ω Switchable Termination
Networks
ABSOLUTE MAXIMUM RATINGS
MAX3406/MAX3407/MAX3408
(All voltages referenced to GND unless otherwise noted.)
V
CC
...........................................................................-0.3V to +6V
ENABLE......................................................-0.3V to (V
CC
+ 0.3V)
A, B (applied individually) ...........................................-4V to +4V
Differential Voltage Across A-B ...................................-4V to +4V
Continuous Power Dissipation (T
A
= +70°C)
5-Pin SOT23 (derate 7.1mW/°C above +70°C)..........571mW
Operating Temperature Range ...........................-40°C to +85°C
Maximum Junction Temperature .....................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
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
CC
= +4.5V to +5.5V, T
A
=T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +5V, T
A
= +25°C.) (Note 1)
PARAMETER
DC CHARACTERISTICS
Supply Range
Supply Current
TERMINATOR NETWORK
MAX3406
-3.6V < V
AB
< ,+3.6V,
ENABLE = 0
-3.6V < V
AB
< +3.6V,
ENABLE = 0,
frequency up to 36MHz
On-Resistance
R
ON
-3.6V < V
AB
< +3.6V,
ENABLE = 1
-3.6V < V
AB
< +3.6V,
ENABLE = 1, frequency
up to 36MHz
Turn-On Time
Turn-Off Time
Input Low Voltage
Input High Voltage
Input Current
Input Hysteresis
t
ON
t
OFF
V
IL
V
IH
I
IL
, I
IH
V
HYST
ENABLE = 0 or V
CC
2.0
-1
200
1
MAX3407/
MAX3408
MAX3406
MAX3407/
MAX3408
MAX3406/
MAX3407
MAX3408
MAX3406/
MAX3407
MAX3408
73.1
97.5
97.5
117
100
120
100
120
Ω
75
100
75
100
50
50
0.8
µs
µs
V
V
µA
mV
76.9
102.5
102.5
123
V
CC
I
CC
V
CC
= +5.5V,
ENABLE = 0 or V
CC
4.5
30
5.5
50
V
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Note 1:
All parameters tested at +25°C. Limits through temperature are guaranteed by design.
2
_______________________________________________________________________________________
75Ω/100Ω/120Ω Switchable Termination
Networks
Typical Operating Characteristics
(V
CC
= +5V, T
A
= +25°C, unless otherwise noted.)
RESISTANCE vs. TEMPERATURE
(MAX3406)
MAX3406/7/8 toc01
MAX3406/MAX3407/MAX3408
RESISTANCE vs. TEMPERATURE
(MAX3407)
MAX3406/7/8 toc02
RESISTANCE vs. TEMPERATURE
(MAX3408)
125
120
RESISTANCE (Ω)
115
110
105
100
95
90
ENABLE = V
CC
ENABLE = 0
MAX3406/7/8 toc03
110
130
120
110
100
90
80
ENABLE = 0
130
100
RESISTANCE (Ω)
ENABLE = 0
90
ENABLE = V
CC
80
RESISTANCE (Ω)
ENABLE = V
CC
70
70
60
-50
-25
0
25
50
75
100
TEMPERATURE (°C)
60
-50
-25
0
25
50
75
100
TEMPERATURE (°C)
-50
-25
0
25
50
75
100
TEMPERATURE (°C)
RESISTANCE vs. INPUT VOLTAGE
(MAX3406)
MAX3406/7/8 toc04
RESISTANCE vs. INPUT VOLTAGE
(MAX3407)
V
B
= 0
120
RESISTANCE (Ω)
110
100
90
80
70
60
ENABLE = V
CC
ENABLE = 0
MAX3406/7/8 toc05
RESISTANCE vs. INPUT VOLTAGE
(MAX3408)
V
B
= 0
125
120
RESISTANCE (Ω)
115
110
105
100
95
90
ENABLE = V
CC
ENABLE = 0
MAX3406/7/8 toc06
120
V
B
= 0
110
RESISTANCE (Ω)
100
90
80
70
60
-3.6
-2.4
-1.2
0
V
AB
(V)
1.2
2.4
ENABLE = 0
ENABLE = V
CC
130
130
3.6
-3.6
-2.4
-1.2
0
V
AB
(V)
1.2
2.4
3.6
-3.6
-2.4
-1.2
0
V
AB
(V)
1.2
2.4
3.6
IMPEDANCE vs. FREQUENCY
75Ω MODE—MAX3406/MAX3407
90
75
MAGNITUDE (Ω)
60
45
30
15
0
0.01
0.1
1
FREQUENCY (MHz)
10
100
PHASE
MAGNITUDE
MAX3406/7/8 toc07
IMPEDANCE vs. FREQUENCY
100Ω MODE—MAX3406/MAX3408
90
60
PHASE (DEGREES)
MAGNITUDE (Ω)
30
0
-30
-60
-90
120
100
80
60
40
20
0
0.01
0.1
1
FREQUENCY (MHz)
10
100
PHASE
MAGNITUDE
MAX3406/7/8 toc08
IMPEDANCE vs. FREQUENCY
120Ω MODE—MAX3407/MAX3408
90
60
PHASE (DEGREES)
MAGNITUDE (Ω)
30
0
-30
-60
-90
140
120
100
80
60
40
20
0.01
0.1
1
FREQUENCY (MHz)
10
100
PHASE
MAGNITUDE
MAX3406/7/8 toc09
90
60
30
0
-30
-60
-90
PHASE (DEGREES)
_______________________________________________________________________________________
3
75Ω/100Ω/120Ω Switchable Termination
Networks
MAX3406/MAX3407/MAX3408
Typical Operating Characteristics (continued)
(V
CC
= +5V, T
A
= +25°C, unless otherwise noted.)
ACCURACY DISTRIBUTION
75Ω MODE
MAX3406/7/8 toc10
ACCURACY DISTRIBUTION
100Ω MODE
MAX3406/7/8 toc11
ACCURACY DISTRIBUTION
120Ω MODE
80%
PERCENTAGE OF PRODUCTION
70%
60%
50%
40%
30%
20%
10%
MAX3406/7/8 toc12
90%
80%
PERCENTAGE OF PRODUCTION
70%
60%
50%
40%
30%
20%
10%
0%
74.40
74.60
74.80
75.00
75.20
75.40
90%
80%
PERCENTAGE OF PRODUCTION
70%
60%
50%
40%
30%
20%
10%
0%
90%
75.60
98.8
99.2
99.6
100.0
100.4
100.8
101.2
0%
118.5
119.0
119.5
120.0
120.5
121.0
121.5
RESISTANCE (Ω)
RESISTANCE (Ω)
RESISTANCE (Ω)
Pin Description
PIN
1
2
3
4
5
NAME
V
CC
GND
ENABLE
B
A
Ground
Digital Control Input. Drive ENABLE high to turn on the internal switch, pull ENABLE low to disable
the internal switch.
Cable Terminator Terminal B
Cable Terminator Terminal A
FUNCTION
Supply Voltage +4.5V to +5.5V. Bypass to GND with a 0.1µF capacitor.
Detailed Description
The MAX3406/MAX3407/MAX3408 are line-terminating
networks. They provide 75Ω, 100Ω, and 120Ω termina-
tion to be compatible with twisted pair or coaxial cable.
The MAX3406/MAX3407/MAX3408 consume only 50µA
supply current and operate from a +4.5V to +5.5V
power supply. They are available in a space-saving 5-
pin SOT23 package. All specifications are guaranteed
over the extended temperature range of -40°C to
+85°C.
The ENABLE pin allows switching from one termination
value to another: 75Ω to 100Ω for the MAX3406, 75Ω to
120Ω for the MAX3407, and 100Ω to 120Ω for the
MAX3408 (Figure 1 and Table 1).
Applications Information
In order for the MAX3406/MAX3407/MAX3408 to termi-
nate transmission lines correctly, they should look like a
precision resistance. These devices look this way under
all operating conditions as can be seen from the
Typical
Operating Characteristics.
The very small variations in
resistance with temperature, input voltage, and frequen-
cy should not be of any concern in most applications,
though the users should be aware of them. The next
three sections describe these variations and explain
what end application effect they could have.
The function of a termination is to minimize line reflec-
tions by terminating a transmission line in its character-
istic impedance. The reflection coefficient for a line of
Z0 characteristic impedance terminated with a given
ZL is:
Voltage Reflection Coefficient = (ZL - Z0)/(ZL + Z0)
4
_______________________________________________________________________________________
75Ω/100Ω/120Ω Switchable Termination
Networks
Table 1. Termination Mode Selection
PART
MAX3406EUK
MAX3407EUK
MAX3408EUK
R
AB
(Ω)
ENABLE = 1
75
75
100
R
AB
(Ω)
ENABLE = 0
100
120
120
mance over discrete 5% resistors with a 100ppm temp-
co, which are typically used for termination, ±5.6%
worst case. The reflections from such a mistermination
are minimal and correspond to a worst-case reflection
coefficient for the MAX3406/MAX3407/MAX3408 of
±0.015 or a -36dB return loss.
MAX3406/MAX3407/MAX3408
Resistance vs. Input Voltage Range
The MAX3406/MAX3407/MAX3408 accept input volt-
ages (V
AB
) from -3.6V to +3.6V. There is virtually no
resistance variation over this range (0.02% typically).
The initial accuracy specifications in the data sheet
already account for resistance variations of the signal
voltage range.
ENABLE
Impedance vs. Frequency
A
MAX3406
MAX3407
MAX3408
V
CC
R1
R2
B
GND
As seen in the
Typical Operating Characteristics,
there
is a slight impedance variation in the MAX3406/
MAX3407/MAX3408 with frequency. The reactive com-
ponents are parasitic inductance and capacitance
associated with packaging, lead frame, and bond
wires. These impedance components are very small up
to frequencies above 20MHz. These parasitics are also
similar to those that would be present with a discrete
resistor terminator, and they can generally be ignored.
These effects should be evaluated for applications with
significant frequency content above 20MHz. This
applies to sine wave sources above 20MHz and square
and video sources above 8MHz. For all intended appli-
cations, E1/T1, Standard Video, etc. they can be
ignored.
Figure 1. Simplified Block Diagram
Decoupling V
CC
The V
CC
pin for the MAX3406/MAX3407/MAX3408 must
be decoupled with a 0.1µF ceramic capacitor to GND
placed as close to the device as possible. This is
required for proper operation of the part.
This is the voltage that would be reflected from any line
termination. As ZL becomes equal to Z0, this quantity
becomes zero. Often this is expressed in dB and is
called return loss. Reflection coefficient values less
than 0.1 corresponding to a return loss of -20dB are
generally seen as adequate. The MAX3406/MAX3407/
MAX3408 will typically provide reflection coefficients
below 0.01 or -40dB return loss.
In most cases, Z0 and ZL are considered real resistive
quantities and the result is a dimensionless scalar
quantity, but the equation is valid in the complex case
as well.
Chip Information
TRANSISTOR COUNT: 102
PROCESS: BiCMOS
Resistance vs. Temperature
The MAX3406/MAX3407/MAX3408 resistance is con-
stant over temperature. The typical temperature coeffi-
cient of resistance is 150ppm/°C. Over a -40°C to
+85°C range centered at +25°C, this would be a ±1%
change in resistance. The initial accuracy at room tem-
perature is ±1.5%. This provides improved perfor-
_______________________________________________________________________________________
5
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