The MAX4310–MAX4315 single-supply mux-amps combine high-speed operation, low-glitch switching, and
excellent video specifications. The six products in this
family are differentiated by the number of multiplexer
inputs and the gain configuration. The MAX4310/
MAX4311/MAX4312 integrate 2-/4-/8-channel multiplexers, respectively, with an adjustable gain amplifier optimized for unity-gain stability. The MAX4313/MAX4314/
MAX4315 integrate 2-/4-/8-channel multiplexers, respectively, with a +2V/V fixed-gain amplifier. All devices have
40ns channel switching time and low 10mVp-p switching
transients, making them ideal for video-switching applications. They operate from a single +4V to +10.5V supply,
or from dual supplies of ±2V to ±5.25V, and they feature
rail-to-rail outputs and an input common-mode voltage
range that extends to the negative supply rail.
The MAX4310/MAX4311/MAX4312 have a -3dB bandwidth of 280MHz/345MHz/265MHz and up to a 460V/µs
slew rate. The MAX4313/MAX4314/MAX4315, with
150MHz/127MHz/97MHz -3dB bandwidths up to a
540V/µs slew rate, and a fixed gain of +2V/V, are ideally
suited for driving back-terminated cables. Quiescent supply current is as low as 6.1mA, while low-power shutdown
mode reduces supply current to as low as 560µA and
places the outputs in a high-impedance state. The
MAX4310–MAX4315’s internal amplifiers maintain an
open-loop output impedance of only 8Ω
over the full output voltage range, minimizing the gain error and bandwidth changes under loads typical of most rail-to-rail
amplifiers. With differential gain and phase errors of
0.06% and 0.08°, respectively, these devices are ideal for
broadcast video applications.
♦ Single-Supply Operation Down to +4V
♦ 345MHz -3dB Bandwidth (MAX4311)
150MHz -3dB Bandwidth (MAX4313)
♦ 540V/µs Slew Rate (MAX4313)
♦ Low 6.1mA Quiescent Supply Current
♦ 40ns Channel Switching Time
♦ Ultra-Low 10mVp-p Switching Transient
♦ 0.06%/0.08° Differential Gain/Phase Error
♦ Rail-to-Rail Outputs: Drives 150Ω to within
730mV of the Rails
♦ Input Common-Mode Range Includes
Negative Rail
♦ Low-Power Shutdown Mode
♦ Available in Space-Saving 8-Pin µMAX®and
16-Pin QSOP Packages
________________________Applications
Video Signal Multiplexing
Video Crosspoint Switching
Flash ADC Input Buffers
Video Cable Drivers
75Ω
High-Speed Signal Processing
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.
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.
to GND, VCCor VEE)....Continuous
OUT
- 0.3V) to (VCC+ 0.3V)
EE
0.3V) to (V
-
EE
= +70°C)
A
CC
+
0.3V)
14-Pin SO (derate 8.3mW/°C above +70°C).................667mW
16-Pin SO (derate 8.7mW/°C above +70°C).................696mW
The MAX4310/MAX4311/MAX4312 combine 2-channel,
4-channel, or 8-channel multiplexers, respectively, with
an adjustable-gain output amplifier optimized for
closed-loop gains of +1V/V (0dB) or greater. The
MAX4313/MAX4314/MAX4315 combine 2-channel, 4channel, or 8-channel multiplexers, respectively, with a
+2V/V (6dB) fixed-gain amplifier, optimized for driving
back-terminated cables. These devices operate from a
single supply voltage of +4V to +10.5V, or from dual
supplies of ±2V to ±5.25V. The outputs may be placed
in a high-impedance state and the supply current minimized by forcing the SHDN pin low. The input multiplexers feature short 40ns channel-switching times and
small 10mVp-p switching transients. The input capacitance remains constant at 1pF whether the channel is
on or off, providing a predictable input impedance to
the signal source. These devices feature single-supply,
rail-to-rail, voltage-feedback output amplifiers that
MAX4310–MAX4315
achieve up to 540V/µs slew rates and up to 345MHz
-3dB bandwidths. These devices also feature excellent
harmonic distortion and differential gain/phase performance.
Applications Information
Rail-to-Rail Outputs, Ground-Sensing Input
The input common-mode range extends from the negative supply rail to VCC- 2.7V with excellent commonmode rejection. Beyond this range, multiplexer
switching times may increase and the amplifier output
is a nonlinear function of the input, but does not undergo phase reversal or latchup.
The output swings to within 250mV of VCCand 40mV of
VEEwith a 10kΩ
output swings from 30mV above VEEto within 730mV of
load. With a 150Ω load to ground, the
the supply rail. Local feedback around the output stage
ensures low open-loop output impedance to reduce
gain sensitivity to load variations. This feedback also
produces demand-driven bias current to the output
transistors for ±95mA drive capability while constraining total supply current to only 6.1mA.
Feedback and Gain Resistor Selection
(MAX4310/MAX4311/MAX4312)
Select the MAX4310/MAX4311/MAX4312 gain-setting
feedback (RF) and input (RG) resistors to fit your application. Large resistor values increase voltage noise and
interact with the amplifier’s input and PC board capacitance. This can generate undesirable poles and zeros,
and can decrease bandwidth or cause oscillations. For
example, a noninverting gain of +2V/V configuration (RF=
RG) using 1kΩ resistors, combined with 2pF of input
capacitance and 1pF of PC board capacitance, causes a
pole at 159MHz. Since this pole is within the amplifier
bandwidth, it jeopardizes stability. Reducing the 1kΩ
resistors to 100Ω extends the pole frequency to 1.59GHz,
but could limit output swing by adding 200Ω in parallel
with the amplifier’s load resistor.
Table 1 shows suggested RF and RG values for the
MAX4310/MAX4311/MAX4312 when operating in the noninverting configuration (shown in Figure 1). These values
provide optimal AC response using surface-mount resistors and good layout techniques, as discussed in the
Layout and Power-Supply Bypassing section.
Stray capacitance at the FB pin causes feedback resistor decoupling and produces peaking in the frequencyresponse curve. Keep the capacitance at FB as low as
possible by using surface-mount resistors and by
avoiding the use of a ground plane beneath or beside
these resistors and the FB pin. Some capacitance is
unavoidable; if necessary, its effects can be neutralized
by adjusting RF. Use 1% resistors to maintain consistency over a wide range of production lots.
Table 1. Bandwidth and Gain with
Suggested Gain-Setting resistors
(MAX4310/MAX4311/MAX4312)
High-Speed, Low-Power, Single-Supply
20
-160
0 50 100 150300 350500
-100
-120
0
LOGIC-LOW THRESHOLD (mV ABOVE V
E
E
)
INPUT CURRENT (µA)
200 250400 450
-60
-140
-
20
-40
-80
OUT
IN-
SHDN, A0, A1, A2
IN+
10kΩ
LOGIC INPUT
MAX431_
0
-10
0
50 100 150300 350500
-7
-8
-1
LOGIC-LOW THRESHOLD (mV ABOVE V
EE
)
INPUT CURRENT ( µA)
200 250400 450
-3
-5
-
9
-
2
-4
-6
Multichannel, Video Multiplexer-Amplifiers
MAX4310–MAX4315
Figure 2. Logic-Low Input Current vs. VIL(
Figure 3. Circuit to Reduce Logic-Low Input Current
SHDN
, A0, A1, A2)
Low-Power Shutdown Mode
All parts feature a low-power shutdown mode that is
activated by driving the SHDN input low. Placing the
amplifier in shutdown mode reduces the quiescent supply current to 560µA and places the output into a highimpedance state, typically 35kΩ. By tying the outputs of
several devices together and disabling all but one of
the paralleled amplifiers’ outputs, multiple devices may
be paralleled to construct larger switch matrices.
For MAX4310/MAX4311/MAX4312 application circuits
operating with a closed-loop gain of +2V/V or greater,
consider the external-feedback network impedance of
all devices used in the mux application when calculat
ing the total load on the output amplifier of the active
device. The MAX4313/MAX4314/MAX4315 have a fixed
gain of +2V/V that is internally set with two 500Ω thinfilm resistors. The impedance of the internal feedback
resistors must be taken into account when operating
multiple MAX4313/MAX4314/MAX4315s in large multiplexer applications. For normal operation, drive SHDN
high. If the shutdown function is not used, connect
SHDN to VCC.
Figure 4. Logic-Low Input Current vs. VILwith 10kΩ Series
Resistor
Layout and Power-Supply Bypassing
The MAX4310–MAX4315 have very high bandwidths and
consequently require careful board layout, including the
possible use of constant-impedance microstrip or
stripline techniques.
To realize the full AC performance of these high-speed
amplifiers, pay careful attention to power-supply bypassing and board layout. The PC board should have at least
two layers: a signal and power layer on one side, and a
large, low-impedance ground plane on the other side.
The ground plane should be as free of voids as possible,
with one exception: the feedback (FB) should have as low
a capacitance to ground as possible. Therefore, layers
that do not incorporate a signal or power trace should not
have a ground plane.
Whether or not a constant-impedance board is used, it is
best to observe the following guidelines when designing
the board:
1) Do not use wire-wrapped boards (they are too
inductive) or breadboards (they are too capacitive).
2) Do not use IC sockets; they increase parasitic
capacitance and inductance.
3) Keep signal lines as short and straight as possible.
-
Do not make 90° turns; round all corners.
4) Observe high-frequency bypassing techniques to
maintain the amplifier’s accuracy and stability.
5) Use surface-mount components. They generally
have shorter bodies and lower parasitic reactance,
yielding better high-frequency performance than
through-hole components.
High-Speed, Low-Power, Single-Supply
MAX4313
R
T
75Ω
8OUT
IN0
IN1
4
5
17
GND
A0
R
T
75Ω
500Ω
500Ω
75Ω CABLE
OUT
R
T
75Ω
R
T
75Ω
75Ω CABLE
75Ω CABLE
10
15
20
25
30
050100150200250
MAX4310-FIG08
CAPACITIVE LOAD (pF)
ISOLATION RESISTANCE R
ISO
(Ω)
100M1G
-6
4
3
2
0
-1
-2
-3
-4
-5
1
100k1M10M
MAX4310-FIG06
FREQUENCY (Hz)
GAIN (dB)
V
OUT
= 100mVp-p
10pF LOAD
5pF LOAD
15pF LOAD
MAX4313
R
ISO
8OUT
IN0
IN1
4
5
17
GND
A0
R
L
C
L
500Ω
500Ω
R
T
75Ω
R
T
75Ω
75Ω CABLE
75Ω CABLE
100M1G
-6
4
3
2
0
-1
-2
-3
-4
-5
1
100k1M10M
MAX4310-FIG09
FREQUENCY (Hz)
GAIN (dB)
V
OUT
= 100mVp-p
47pF LOAD
90pF LOAD
120pF LOAD
Multichannel, Video Multiplexer-Amplifiers
Figure 5. Video Line Driver
Figure 8. Optimal Isolation Resistance vs. Capacitive Load
MAX4310–MAX4315
Figure 6. Small-Signal Gain vs. Frequency with a Capacitive
Load and No-Isolation Resistor
Figure 9. Small-Signal Gain vs. Frequency with a Capacitive
Load and 27Ω No-Isolation Resistor
The bypass capacitors should include a 100nF, ceramic surface-mount capacitor between each supply pin
and the ground plane, located as close to the package
as possible. Optionally, place a 10µF tantalum capacitor at the power-supply pin’s point of entry to the PC
board to ensure the integrity of incoming supplies. The
power-supply trace should lead directly from the tantalum capacitor to the V
CC
parasitic inductance, keep PC traces short and use surface-mount components. If input termination resistors
and output back-termination resistors are used, they
should be surface-mount types, and should be placed
as close to the IC pins as possible.
and VEEpins. To minimize
High-Speed, Low-Power, Single-Supply
MAX4310/MAX4313
SS
S
S
HH
H
H
DD
D
D
NN
N
N
A2A1A0C
HANNEL SELECTED
0
—
—
X
None, High-Z Output
1
—
—
00
1
—
—
11
MAX4311/MAX4314
SSSSHHHHDDDDNN
NN
A2A1A0C
HANNEL SELECTED
0
—
XXNone, High-Z Output
1
—
000
1
—
011
1
—
102
1
—
113
MAX4312/MAX4315
SSSSHHHHDDDDNN
NN
A2A1A0
CHANNEL SELECTED
0XXXNone, High-Z Output
10000
10011
10102
10113
11004
11015
11106
11117
Multichannel, Video Multiplexer-Amplifiers
Figure 10. High-Speed EV Board Layout—Component Side
Figure 11. High-Speed EV Board Layout—Solder Side
The MAX4310–MAX4315 are well-suited to drive coaxial
transmission lines when the cable is terminated at both
ends, as shown in Figure 5. Cable frequency response
can cause variations in the signal’s flatness.
Driving Capacitive Loads
A correctly terminated transmission line is purely resis
tive and presents no capacitive load to the amplifier.
Reactive loads decrease phase margin and may pro
duce excessive ringing and oscillation (see
Operating Characteristics).
Another concern when driving capacitive loads originates from the amplifier’s output impedance, which
appears inductive at high frequencies. This inductance
forms an L-C resonant circuit with the capacitive load,
which causes peaking in the frequency response and
degrades the amplifier’s phase margin.
Although the MAX4310–MAX4315 are optimized for AC
performance and are not designed to drive highly capacitive loads, they are capable of driving up to 20pF without
oscillations. However, some peaking may occur in the frequency domain (Figure 6). To drive larger capacitive
loads or to reduce ringing, add an isolation resistor
between the amplifier’s output and the load (Figure 7).
The value of RISO depends on the circuit’s gain and
the capacitive load (Figure 8). Figure 9 shows the
MAX4310–MAX4315 frequency response with the isolation resistor and a capacitive load. With higher capaci-
tive values, bandwidth is dominated by the RC network
formed by R
itself is much higher. Also note that the isolation resistor
forms a divider that decreases the voltage delivered to
the load.
and CL; the bandwidth of the amplifier
ISO
MAX4310–MAX4315
High-Speed, Low-Power, Single-Supply
MAX4313
0.1
µF
75Ω
8OUT
3
V
CC
+4V TO +10.5V
IN1
IN0
5
4
1627
A0
75Ω
500Ω
GND
V
EE
SHDN
500Ω
VIDEO
OUTPUT
75Ω CABLE
Multichannel, Video Multiplexer-Amplifiers
The multiplexer architecture of the MAX4310–MAX4315
Digital Interface
ensures that no two input channels are ever connected
together. Channel selection is accomplished by applying a binary code to channel address inputs. The
address decoder selects input channels, as shown in
Table 2. All digital inputs are CMOS compatible.
High-Speed Evaluation Board
Figures 10 and 11 show the evaluation board and present a suggested layout for the circuits. This board was
developed using the techniques described in the
Layout and Power-Supply Bypassing section. The
smallest available surface-mount resistors were used
MAX4310–MAX4315
for feedback and back-termination to minimize their distance from the part, reducing the capacitance associated with longer lead lengths.
SMA connectors were used for best high-frequency
performance. Inputs and outputs do not match a 75Ω
line, but this does not affect performance since distances are extremely short. However, in applications
that require lead lengths greater than one-quarter of the
wavelength of the highest frequency of interest, use
constant-impedance traces. Fully assembled evaluation
boards are available for the MAX4313 in an SO package.
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.