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19-1262; Rev 0; 3/98
Low-Voltage, Bidirectional RF/Video Switch
General Description
The MAX4529 is a low-voltage T-switch designed for switching RF and video signals from DC to 300MHz in 50 and 75 systems. This switch is constructed in a "T" configuration, ensuring excellent high-frequency off isolation of -80dB at 10MHz. The MAX4529 can handle Rail-to-Rail(R) analog signals in either direction. On-resistance (70 max) is flat (0.5 max) over the specified signal range, using 5V supplies. The off leakage current is less than 1nA at +25C and 20nA at +85C. This CMOS switch can operate with dual power supplies ranging from 2.7V to 6V or a single supply between +2.7V and +12V. All digital inputs have 0.8V/2.4V logic thresholds, ensuring both TTL- and CMOS-logic compatibility when using 5V or a single +5V supply.
____________________________Features
o High 50 Off Isolation: -80dB at 10MHz o DC to 300MHz -3dB Signal Bandwidth o 70 Signal Paths with 5V Supplies o 10 Signal-Path Flatness with 5V Supplies o 2.7V to 6V Dual Supplies +2.7V to +12V Single Supply o Low Power Consumption: <1W o Rail-to-Rail Bidirectional Signal Handling o >2kV ESD Protection per Method 3015.7 o TTL/CMOS-Compatible Inputs with Single +5V or 5V
MAX4529
Ordering Information
PART TEMP. RANGE 0C to +70C 0C to +70C 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PINPACKAGE 8 Plastic DIP 8 Narrow SO 8 MAX 6 SOT23-6 Dice* 8 Plastic DIP 8 Narrow SO 8 MAX 6 SOT23-6 SOT TOP MARK -- -- -- AAAQ -- -- -- -- AAAQ
________________________Applications
RF Switching Video Signal Routing High-Speed Data Acquisition Test Equipment ATE Equipment Networking
MAX4529CPA MAX4529CSA MAX4529CUA MAX4529CUT-T MAX4529C/D MAX4529EPA MAX4529ESA MAX4529EUA MAX4529EUT-T
*Contact factory for dice specifications.
_______________________Pin Configurations/Functional Diagrams/Truth Table
MAX4529
N.C. 1 NC 2 GND 3 IN 4 8 V+ 7 COM 6 N.C. 5 VNC 1 V+ 2 V- 3
MAX4529
6 COM 5 GND 4 IN
LOGIC 0 1
SWITCH ON OFF
SOT23-6
DIP/SO/MAX
N.C. = NOT INTERNALLY CONNECTED
Rail-to-Rail is a registered trademark of Nippon Motorola Ltd.
________________________________________________________________ Maxim Integrated Products 1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 408-737-7600 ext. 3468.
Low-Voltage, Bidirectional RF/Video Switch MAX4529
ABSOLUTE MAXIMUM RATINGS
(Voltages referenced to GND) V+ ...........................................................................-0.3V, +13.0V V- ............................................................................-13.0V, +0.3V V+ to V-...................................................................-0.3V, +13.0V All Other Pins (Note 1) ..........................(V- - 0.3V) to (V+ + 0.3V) Continuous Current into Any Terminal..............................10mA Peak Current into Any Terminal (pulsed at 1ms, 10% duty cycle)..................................50mA ESD per Method 3015.7 ..................................................>2000V Continuous Power Dissipation (TA = +70C) 8-Pin Plastic DIP (derate 9.09mW/C above +70C) ...727mW 8-Pin SO (derate 5.88mW/C above +70C)............... 471mW 8-Pin MAX (derate 4.1mW/C above +70C) ............. 330mW 6-Pin SOT23-6 (derate 7.1mW/C above +70C) ........571mW Operating Temperature Ranges MAX4529C_ E .....................................................0C to +70C MAX4529E_ E ..................................................-40C to +85C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10sec) .............................+300C
Note 1: Voltages on all other pins exceeding V+ or V- 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--Dual Supplies
(V+ = +4.5V to +5.5V, V- = -4.5V to -5.5V, VINL = 0.8V, VINH = 2.4V, VGND = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER ANALOG SWITCH Analog Signal Range Signal-Path On-Resistance Signal-Path On-Resistance Flatness (Note 4) NC Off Leakage Current (Notes 5, 6) COM Off Leakage Current (Notes 5, 6) COM On Leakage Current (Notes 5, 6) LOGIC INPUT IN Input Logic Threshold High IN Input Logic Threshold Low IN Input Current Logic High or Low VINH VINL IINH, IINL VIN = 0.8V or 2.4V C, E C, E C, E 0.8 -1 1.5 1.5 0.03 1 2.4 V V A VCOM, VNC RON RFLAT(ON) INC(OFF) ICOM(OFF) ICOM(ON) (Note 3) V+ = 5V, V- = -5V, VCOM = 3V, ICOM = 1mA V+ = 5V; V- = -5V; VCOM = 3V, 0V, -3V; ICOM = 1mA V+ = 5.5V, V- = -5.5V, VCOM = 4.5V, VNC = 4.5V V+ = 5.5V, V- = -5.5V, VCOM = 4.5V, VNC = 4.5V V+ = 5.5V, V- = -5.5V, VCOM = 4.5V C, E +25C C, E +25C +25C C, E +25C C, E +25C C, E -1 -20 -1 -20 -2 -40 0.02 0.02 5 0.02 V45 V+ 70 100 10 1 20 1 20 2 40 V nA nA nA SYMBOL CONDITIONS TA MIN TYP (Note 2) MAX UNITS
2
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Low-Voltage, Bidirectional RF/Video Switch
ELECTRICAL CHARACTERISTICS--Dual Supplies (continued)
(V+ = +4.5V to +5.5V, V- = -4.5V to -5.5V, VINL = 0.8V, VINH = 2.4V, VGND = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER SYMBOL CONDITIONS TA MIN TYP (Note 2) 45 37 MAX UNITS
MAX4529
SWITCH DYNAMIC CHARACTERISTICS Turn-On Time Turn-Off Time Charge Injection (Note 3) NC Off Capacitance COM_ Off Capacitance COM_ On Capacitance Off Isolation (Note 7) -3dB Bandwidth Distortion POWER SUPPLY Power-Supply Range V+ Supply Current V - Supply Current V+, VI+ IV+ = 5.5V, VIN = 0V or V+, V- = -5.5V V+ = 5.5V, VIN = 0V or V+, V- = -5.5V C, E +25C C, E +25C C, E 2.7 -1 -10 -1 -10 0.05 0.05 6 1 10 1 10 V A A tON tOFF Q CNC(OFF) CCOM(OFF) CCOM(ON) VISO BW THD+N VCOM = 3V, V+ = 5V, V- = -5V, Figure 2 VCOM = 3V, V+ = 5V, V- = -5V, Figure 2 CL = 1.0nF, VNC = 0V, RS = 0, Figure 3 VNC = GND, f = 1MHz, Figure 5 VCOM = 0V, f = 1MHz, Figure 5 VCOM = VNC = 0V, f = 1MHz, Figure 5 RL = 50, VCOM = 1VRMS, f = 10MHz, Figure 4 RL = 50, Figure 4 VIN = 5Vp-p, f < 20kHz, 600 in and out +25C C, E +25C C, E +25C +25C +25C +25C +25C +25C +25C 5 6 6 11.5 -80 300 0.004 75 100 75 100 10 ns ns pC pF pF pF dB MHz %
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3
Low-Voltage, Bidirectional RF/Video Switch MAX4529
ELECTRICAL CHARACTERISTICS--Single +5V Supply
(V+ = +4.5V to +5.5V, V- = 0V, VINL = 0.8V, VINH = 2.4V, VGND = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER ANALOG SWITCH Analog Signal Range Signal-Path On-Resistance NC Off Leakage Current (Notes 5, 6, 8) COM Off Leakage Current (Notes 5, 6, 8) COM On Leakage Current (Notes 5, 6, 8) LOGIC INPUT IN Input Logic Threshold High IN Input Logic Threshold Low IN Input Current Logic High or Low VINH VINL IINH, IINL VIN = 0.8V or 2.4V C, E C, E C, E 0.8 -1 1.5 1.5 0.03 1 2.4 V V A VCOM, VNC RON INC(OFF) ICOM(OFF) ICOM(ON) (Note 3) V+ = 5V, VCOM = 3V, ICOM = 1mA V+ = 5.5V, VCOM = 1V, VNC = 4.5V V+ = 5.5V, VCOM = 1V, VNC = 4.5V V+ = 5.5V; VCOM = 1V, 4.5V +25C +25C C, E +25C C, E +25C C, E +25C C, E -1 -20 -1 -20 -2 -40 0.02 0.02 0.02 0 70 V+ 120 150 1 20 1 20 2 40 V nA nA nA SYMBOL CONDITIONS TA MIN TYP (Note 2) MAX UNITS
SWITCH DYNAMIC CHARACTERISTICS Turn-On Time (Note 3) Turn-Off Time (Note 3) Charge Injection (Note 3) Off-Isolation (Note 7) POWER SUPPLY Power-Supply Range V+ Supply Current V+ I+ V- = 0V V+ = 5.5V, VIN = 0V or V+ C, E +25C C, E 2.7 -1 -10 0.05 12.0 1 10 V A tON tOFF Q VISO VCOM = 3V, V+ = 5V, Figure 2 VCOM = 3V, V+ = 5V, Figure 2 CL = 1.0nF, VNC = 2.5V, RS = 0, Figure 3 RL = 50, VCOM = 1VRMS, f = 10MHz, Figure 4 +25C C, E +25C C, E +25C +25C 1.5 -75 43 65 100 120 90 110 10 ns ns pC dB
4
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Low-Voltage, Bidirectional RF/Video Switch
ELECTRICAL CHARACTERISTICS--Single +3V Supply
(V+ = +2.7V to +3.6V, V- = 0V, VINL = 0.4V, VINH = 2.4V, VGND = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER ANALOG SWITCH Analog Signal Range Signal-Path On-Resistance LOGIC INPUT IN Input Logic Threshold High IN Input Logic Threshold Low IN Input Current Logic High or Low VINH VINL IINH, IINL (Note 3) (Note 3) VIN = 0.4V or 2.4V (Note 3) VCOM = 1.5V, V+ = 2.7V, Figure 2 (Note 3) VCOM = 1.5V, V+ = 2.7V, Figure 2 (Note 3) C, E C, E C, E +25C C, E +25C C, E +25C C, E -1 -10 0.05 70 0.4 -1 150 1.0 1.0 1 300 400 150 200 1 10 2.4 V V A VCOM, VNC RON (Note 3) V+ = 2.7V, VCOM = 1.5V, ICOM = 0.1mA +25C +25C C, E 0 175 V+ 400 500 V SYMBOL CONDITIONS TA MIN TYP (Note 2) MAX UNITS
MAX4529
SWITCH DYNAMIC CHARACTERISTICS Turn-On Time Turn-Off Time POWER SUPPLY V+ Supply Current I+ V+ = 3.6V, VIN = 0V or V+ A tON tOFF ns ns
Note 2: The algebraic convention is used in this data sheet; the most negative value is shown in the minimum column. Note 3: Guaranteed by design. Note 4: Resistance flatness is defined as the difference between the maximum and the minimum value of on-resistance as measured over the specified analog signal range. Note 5: Leakage parameters are 100% tested at the maximum rated hot temperature and guaranteed by correlation at +25C. Note 6: Guaranteed by design, not subject to production testing in SOT package. Note 7: Off isolation = 20log10 (VCOM / VNC), VCOM = output, VNC = input to off switch. Note 8: Leakage testing for single-supply operation is guaranteed by testing with dual supplies.
__________________________________________Typical Operating Characteristics
(V+ = +5V, V- = -5V, GND = 0V, TA = +25C, packages are surface mount, unless otherwise noted.)
ON-RESISTANCE vs. VCOM (DUAL SUPPLIES)
MAX4529-01
ON-RESISTANCE vs. VCOM (SINGLE SUPPLY)
MAX4529-02
ON-RESISTANCE vs. VCOM AND TEMPERATURE (DUAL SUPPLIES)
+125C +85C +70C 40 0C 30 20 10 0 V+ = 5V V- = -5V -5 -4 -3 -2 -1 0 1 2 3 4 5 VCOM (V) -40C -55C +25C
MAX4529-03
1000 V+ = 1.2V V- = -1.2V ON-RESISTANCE () V+ = 2.0V V- = -2.0V 100 V+ = 2.7V V- = -2.7V
1000 V+ = 1.2V V+ = 2.0V ON-RESISTANCE () V+ = 2.7V V+ = 3.3V 100 V+ = 5.0V V- = 0V
70 60 ON-RESISTANCE () 50
V+ = 5.0V V- = -5.0V 10 -5 -4 -3 -2 -1 0 1
V+ = 3.3V V- = -3.3V 10 2 3 4 5 0 1 2 3 4
V+ = 7.5V V+ = 10.0V
5
6
7
8
9
10
VCOM (V)
VCOM (V)
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5
Low-Voltage, Bidirectional RF/Video Switch MAX4529
____________________________Typical Operating Characteristics (continued)
(V+ = +5V, V- = -5V, GND = 0V, TA = +25C, packages are surface mount, unless otherwise noted.)
ON-RESISTANCE vs. VCOM AND TEMPERATURE (SINGLE SUPPLY)
MAX4529-04
SUPPLY, COM, AND NC LEAKAGE CURRENTS vs. TEMPERATURE
MAX4529-05
CHARGE INJECTION vs. VCOM
MAX4529-06
70 60 ON-RESISTANCE () 50 40 30 20 10 0 0 V+ = 5V V- = -5V -40C -55C +70C 0C +125C +85C
1,000,000 100,000 10,000 CURRENT (pA) 1000 100 10 1 0.1 0.01 -55 -35 -15 5 25 45 65 IOFF ION V+ = 5V V- = -5V I+, I-
15
12 V+ = 5V V- = -5V V+ = 5V V- = 0V V+ = 3V V- = 0V
Q (pC) 85 105 125
+25C
9
6
3
0 -5 -4 -3 -2 -1 0 1 2 3 4 5 TEMPERATURE (C) VCOM (V)
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 VCOM (V)
ON-TIME vs. TEMPERATURE
160 140 120 100 80 60 40 20 0 -55 -35 -15 5 25 45 65 85 105 125 TEMPERATURE (C) V+ = 5V V- = -5V tOFF (ns) tON (ns) V+ = 5V V- = 0V
MAX4529-07
OFF-TIME vs. TEMPERATURE
70 60 50 40 30 20 10 0 -55 -35 -15 5 25 45 65 85 105 125 TEMPERATURE (C) V+ = 5V V- = -5V V+ = 3V V- = 0V V+ = 5V V- = 0V
MAX4529-08
LOGIC-LEVEL THRESHOLD vs. SUPPLY VOLTAGE
MAX4529-09
180 V+ = 3V V- = 0V
80
3.0 2.5 2.0 1.5 1.0 0.5 0 0 1 2 3 4 5 6 V+ (V) 7 8
LOGIC-LEVEL THRESHOLD (V)
9 10 11 12
FREQUENCY RESPONSE
0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 0.1 1 10 FREQUENCY (MHz) 100 LOSS (dB)
MAX4529-10
TOTAL HARMONIC DISTORTION vs. FREQUENCY
50 40 30 20 10 0 -10 -20 -30 -40 -50 -60 1000
MAX4529-11
60
100
ON LOSS
ON PHASE (DEGREES)
10 THD (%) 1 0.1 10 100 1k FREQUENCY (Hz) 10k 30k
ON PHASE
OFF ISOLATION
6
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Low-Voltage, Bidirectional RF/Video Switch
Pin Description
PIN NAME SOT23-6 -- 1 2 3 4 5 6 DIP/SO/MAX 1, 6 2 8 5 4 3 7 N.C. NC V+ VIN GND COM Not Internally Connected Analog Switch Normally Closed** Terminal Positive Supply-Voltage Input (analog and digital). The voltage difference between V+ and V- should never exceed 12V. -5V Supply Input. Connect to GND for single-supply operation. Logic-Level Control Input. Logic-level voltages should never exceed V+ or V-. RF and Logic Ground. Connect to ground plane. Analog Switch Common** Terminal. Analog signal voltages should never exceed V+ or V-. FUNCTION*
MAX4529
* All pins except N.C. have ESD diodes to V- and V+. ** NC and COM pins are identical and interchangeable. Either may be considered as an input or output; signals pass equally well in either direction.
Theory of Operation
Logic-Level Translators
The MAX4529 is constructed as a high-frequency "T" switch, as shown in Figure 1. The logic-level input, IN, is translated by amplifier A1 into a V+ to V- logic signal that drives inverter A2. Amplifier A2 drives the gates of N-channel MOSFETs N1 and N2 from V+ to V-, turning them fully on or off. The same signal drives inverter A3 (which drives the P-channel MOSFETs P1 and P2) from V+ to V-, turning them fully on or off, and drives the Nchannel MOSFET N3 off and on. The logic-level threshold is determined by V+ and GND. The voltage on GND is usually at ground potential, but it may be set to any voltage between (V+ - 2V) and V-. When the voltage between V+ and GND is less than 2V, the level translators become very slow and unreliable. Normally, GND should be connected to the ground plane.
COM
NORMALLY CLOSED SWITCH CONSTRUCTION N1 D IN 0 1 V+ A1 IN S GND VESD DIODES ON GND, IN, COM, AND NC VV+ A2 A3 D N3 COM - NC ON OFF P1 S D S P2 D S D N2 S NC
Figure 1. T-Switch Construction
Switch On Condition
When the switch is on, MOSFETs N1, N2, P1, and P2 are on and MOSFET N3 is off. The signal path is COM to NC, and because both N-channel and P-channel MOSFETs act as pure resistances, it is symmetrical (i.e., signals may pass in either direction). The off MOSFET, N3, has no DC conduction, but has a small amount of capacitance to GND. The four on MOSFETs also have capacitance to ground that, together with the series resistance, forms a lowpass filter. All of these capaci-
tances are distributed evenly along the series resistance, so they act as a transmission line rather than a simple R-C filter. This helps to explain the exceptional 300MHz bandwidth when the switches are on. Typical attenuation in 50 systems is -2dB and is reasonably flat up to 100MHz. Higher-impedance circuits show even lower attenuation (and vice versa), but slightly lower bandwidth due to the increased effect of the internal and external capacitance and the switch's internal resistance.
7
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Low-Voltage, Bidirectional RF/Video Switch MAX4529
The MAX4529 is a optimized for 5V operation. Using lower supply voltages or a single supply increases switching time, on-resistance (and therefore on-state attenuation), and nonlinearity. switched V+ and V- signals to drive the gates of the analog switches. This drive signal is the only connection between the logic supplies and the analog supplies. All pins have ESD protection to V+ and to V-. Increasing V- has no effect on the logic-level thresholds, but it does increase the drive to the P-channel switches, reducing their on-resistance. V- also sets the negative limit of the analog signal voltage. The logic-level thresholds are CMOS and TTL compatible when V+ is +5V. As V+ is raised, the threshold increases slightly; when V+ reaches +12V, the level threshold is about 3.1V, which is above the TTL output high-level minimum of 2.8V, but still compatible with CMOS outputs.
Switch Off Condition
When the switch is off, MOSFETs N1, N2, P1, and P2 are off and MOSFET N3 is on. The signal path is through the off-capacitances of the series MOSFETs, but it is shunted to ground by N3. This forms a highpass filter whose exact characteristics depend on the source and load impedances. In 50 systems, and below 10MHz, the attenuation can exceed 80dB. This value decreases with increasing frequency and increasing circuit impedances. External capacitance and board layout have a major role in determining overall performance.
Applications Information
Power-Supply Considerations
Overview The MAX4529's construction is typical of most CMOS analog switches. It has three supply pins: V+, V-, and GND. V+ and V- are used to drive the internal CMOS switches and set the limits of the analog voltage on any switch. Reverse ESD protection diodes are internally connected between each analog signal pin and both V+ and V-. If the voltage on any pin exceeds V+ or V-, one of these diodes will conduct. During normal operation these reverse-biased ESD diodes leak, forming the only current drawn from V-.
Virtually all the analog leakage current is through the ESD diodes. Although the ESD diodes on a given signal pin are identical, and therefore fairly well balanced, they are reverse biased differently. Each is biased by either V+ or V- and the analog signal. This means their leakages vary as the signal varies. The difference in the two diode leakages from the signal path to the V+ and V- pins constitutes the analog signal-path leakage current. All analog leakage current flows to the supply terminals, not to the other switch terminal. This explains how both sides of a given switch can show leakage currents of either the same or opposite polarity. When the switch is on, there is no connection between the analog signal paths and GND. The analog signal paths consist of an N-channel and P-channel MOSFET with their sources and drains paralleled and their gates driven out of phase with V+ and V- by the logic-level translators. V+ and GND power the internal logic and logic-level translators, and set the input logic thresholds. The logic-level translators convert the logic levels to
8
Bipolar-Supply Operation The MAX4529 operates with bipolar supplies between 2.7V and 6V. The V+ and V- supplies need not be symmetrical, but their sum cannot exceed the absolute maximum rating of 13.0V. Do not connect the MAX4529 V+ pin to +3V and connect the logic-level input pins to TTL logic-level signals. TTL logic-level outputs can exceed the absolute maximum ratings, causing damage to the part and/or external circuits.
CAUTION: The absolute maximum V+ to V- differential voltage is 13.0V. Typical "6-Volt" or "12-Volt" supplies with 10% tolerances can be as high as 13.2V. This voltage can damage the MAX4529. Even 5% tolerance supplies may have overshoot or noise spikes that exceed 13.0V.
Single-Supply Operation The MAX4529 operates from a single supply between +2.7V and +12V when V- is connected to GND. All of the bipolar precautions must be observed. Note, however, that these parts are optimized for 5V operation, and most AC and DC characteristics are degraded significantly when departing from 5V. As the overall supply voltage (V+ to V-) is lowered, switching speed, on-resistance, off isolation, and distortion are degraded (see Typical Operating Characteristics). Single-supply operation also limits signal levels and interferes with grounded signals. When V- = 0V, AC signals are limited to -0.3V. Voltages below -0.3V can be clipped by the internal ESD-protection diodes, and the parts can be damaged if excessive current flows.
_______________________________________________________________________________________
Low-Voltage, Bidirectional RF/Video Switch
Single-Supply Operation Above 5V The MAX4529 is designed for operation from single +5V or dual 5V supplies. As V+ is increased above 5V, the logic-level threshold voltage increases and the supply current increases. In addition, if the logic levels are not driven rail-to-rail, the analog signal pins, COM and NC, can conduct a significant DC current (up to 1mA) to the supply pins. This current can add an unwanted DC bias to the signal. Therefore, when operating V+ above 5V, always drive the IN pin rail-to-rail. Power Off When power to the MAX4529 is off (i.e., V+ = 0V and V= 0V), the Absolute Maximum Ratings still apply. This means that neither logic-level inputs on IN nor signals on COM or NC can exceed 0.3V. Voltages beyond 0.3V cause the internal ESD-protection diodes to conduct, and the parts can be damaged if excessive current flows. AC Ground and Bypassing A ground plane is mandatory for satisfactory highfrequency operation. (Prototyping using hand wiring or wire-wrap boards is strongly discouraged.) Connect any 0V GND pins to the ground plane with solid copper. (The GND pin extends the high-frequency ground through the package wire-frame, into the silicon itself, thus improving isolation.) The ground plane should be solid metal underneath the device, without interruptions. There should be no traces under the device itself. For DIP packages, this applies to both sides of a twosided board. Failure to observe this will have a minimal effect on the "on" characteristics of the switch at high frequencies, but it will degrade the off isolation and crosstalk. V+ and V- pins should be bypassed to the ground plane with surface-mount 10nF capacitors. For DIP packages, they should be mounted as close as possible to the pins on the same side of the board as the device. Do not use feedthroughs or vias for bypass capacitors. For surface-mount packages, the pins are so close to each other that the bypass capacitors should be mounted on the opposite side of the board from the device. In this case, use short feedthroughs or vias, directly under the V+ and V- pins. Any GND pin not connected to 0V should be similarly bypassed. If Vis 0V, connect it directly to the ground plane with solid copper. Keep all leads short.
MAX4529
Grounding
DC Ground Considerations Satisfactory high-frequency operation requires that careful consideration be given to grounding. For most applications, a ground plane is strongly recommended, and GND should be connected to it with solid copper.
In systems that have separate digital and analog (signal) grounds, connect these switch GND pins to analog ground. Preserving a good signal ground is much more important than preserving a digital ground. Ground current is only a few nanoamps. The logic-level input, IN, has voltage thresholds determined by V+ and GND. (V- does not influence the logic-level threshold.) With +5V and 0V applied to V+ and GND, the threshold is about 1.6V, ensuring compatibility with TTL- and CMOS-logic drivers. The GND pin can be connected to separate voltage potentials if the logic-level input is not a normal logic signal. (The GND voltage cannot exceed (V+ - 2V) or V-.) Elevating GND reduces off isolation. Note, however, that IN can be driven more negative than GND, as far as V-. GND does not have to be removed from 0V when IN is driven from bipolar sources, but the voltage on IN should never exceed V-. GND should be separated from 0V only if the logic-level threshold has to be changed. If the GND pin is not connected to 0V, it should be bypassed to the ground plane with a surface-mount 10nF capacitor to maintain good RF grounding. DC current in the IN and GND pins is less than 1nA, but increases with switching frequency.
Signal Routing
Keep all signal leads as short as possible. Separate all signal leads from each other and other traces with the ground plane on both sides of the board. Where possible, use coaxial cable instead of printed circuit board traces.
Board Layout
IC sockets degrade high-frequency performance and should not be used if signal bandwidth exceeds 5MHz. Surface-mount parts, having shorter internal lead frames, provide the best high-frequency performance. Keep all bypass capacitors close to the device, and separate all signal leads with ground planes. Such grounds tend to be wedge-shaped as they get closer to the device. Use vias to connect the ground planes on each side of the board, and place the vias in the apex of the wedge-shaped grounds that separate signal leads. Logic-level signal lead placement is not critical.
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9
Low-Voltage, Bidirectional RF/Video Switch MAX4529
______________________________________________Test Circuits/Timing Diagrams
10nF +5V
V+ NC 3V
V+ VIN 0V 50% 50%
MAX4529
VIN IN GND 50 10nF -5V VRL = 50 VOUT COM VOUT 0V tOFF 90%
90%
tON
V- IS CONNECTED TO GND (OV) FOR SINGLE-SUPPLY OPERATION.
Figure 2. Switching Time
10nF
+5V
V+ NC VNC = 0V VIN
V+ 0V
MAX4529
VIN IN GND 50 10nF -5V V- IS CONNECTED TO GND (0V) FOR SINGLE-SUPPLY OPERATION. VOUT IS THE MEASURED VOLTAGE DUE TO CHARGE TRANSFER ERROR Q WHEN THE CHANNEL TURNS OFF. Q = VOUT x CL VCOM VOUT CL = 1000pF VOUT VOUT
Figure 3. Charge Injection
10
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Low-Voltage, Bidirectional RF/Video Switch
_________________________________Test Circuits/Timing Diagrams (continued)
+5V 10nF NETWORK ANALYZER 0V OR V+ IN V+ NC VIN 50 50
MAX4529
V OFF ISOLATION = 20log OUT VIN V ON LOSS = 20log OUT VIN
MAX4529
COM GND VVOUT MEAS REF
50
50
10nF -5V MEASUREMENTS ARE STANDARDIZED AGAINST SHORT AT IC TERMINALS. OFF ISOLATION IS MEASURED BETWEEN COM_ AND "OFF" NC TERMINAL. ON LOSS IS MEASURED BETWEEN COM_ AND "ON" NC TERMINAL. SIGNAL DIRECTION THROUGH SWITCH IS REVERSED; WORST VALUES ARE RECORDED. V- IS CONNECTED TO GND (0V) FOR SINGLE-SUPPLY OPERATION.
Figure 4. On Loss and Off Isolation
___________________Chip Topography
V+
10nF +5V
NC
0V OR V+ IN V+ NC
COM
MAX4529
COM GND V-
1MHz CAPACITANCE ANALYZER
0.054" (1.372mm)
N.C.
10nF -5V
N.C.
GND
Figure 5. NC and COM Capacitance
IN V-
0.038" (0.965mm)
______________________________________________________________________________________
TRANSISTOR COUNT: 78 SUBSTRATE INTERNALLY CONNECTED TO VN.C. = NO CONNECTION
11
Low-Voltage, Bidirectional RF/Video Switch MAX4529
________________________________________________________Package Information
6LSOT.EPS
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.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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