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19-1415; Rev 1; 8/99
Fault-Protected, High-Voltage Signal-Line Protectors
General Description
The MAX4506/MAX4507 multiple, two-terminal signal-line protectors are pin-compatible with the industry-standard MAX366/MAX367. These new circuit protectors feature fault-protected inputs and Rail-to-Rail(R) signal handling capability. The input pins are protected from overvoltage faults up to 36V with power on or 40V with power off. During a fault condition, the input terminal becomes an open circuit and only nanoamperes of leakage current flow from the source; but the switch output (OUT_) furnishes typically 19mA from the appropriate polarity supply to the load. This ensures unambiguous rail-to-rail outputs when a fault begins and ends. The MAX4506 contains three independent protectors while the MAX4507 contains eight independent protectors. They can protect both unipolar and bipolar analog signals using either unipolar (+9V to +36V) or bipolar (8V to 18V) power supplies. These devices have no logic control inputs; the protectors are designed to be always-on when the supplies are on. On-resistance is 100 max and matched within 7, and on-leakage is less than 0.5nA at TA = +25C. The MAX4506 is available in 8-pin SO/DIP packages. The MAX4507 is available in 20-pin SSOP and 18-pin SO/DIP packages.
Features
o Overvoltage Protection 40V with Power Off 36V with Power On o Open Signal Paths with Power Off o Output Clamps to Either Rail with an Input Overvoltage o Any On Channel Output is Not Affected by an Overvoltage to Any Other Channel o 100 max On-Resistance o 10ns Overvoltage Turn-On Delay o No Latchup During Power Sequencing o Rail-to-Rail Signal Handling o 500 Output Clamp Resistance During Overvoltage
MAX4506/MAX4507
Ordering Information
PART MAX4506CSA MAX4506CPA MAX4506C/D MAX4506ESA MAX4506EPA MAX4506MJA TEMP. RANGE 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C -55C to +125C PIN-PACKAGE 8 SO 8 Plastic DIP Dice* 8 SO 8 Plastic DIP 8 CERDIP**
Applications
Process-Control Systems Hot-Insertion Boards/Systems Data-Acquisition Systems Redundant/Backup Systems ATE Equipment Sensitive Instruments
Ordering Information continued at end of data sheet. *Contact factory for dice specifications. **Contact factory for availability.
Typical Operating Circuit
SWITCHED +15V
Pin Configurations
TOP VIEW
P
MAX4506
1 IN1 2 IN2 3 IN3 4 V-
V+
8
+15V
IN1 1 IN2 2
8 7
V+ OUT1 OUT2 OUT3
OUT1 7 OUT2 6 OUT3 5 100k OP AMP
MAX4506
IN3 3 6 5 V- 4
SO/DIP
-15V
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
Pin Configurations continued at end of data sheet.
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Fault-Protected, High-Voltage Signal-Line Protectors MAX4506/MAX4507
ABSOLUTE MAXIMUM RATINGS
(Voltages Referenced to GND) V+ ........................................................................-0.3V to +44.0V V- .........................................................................-44.0V to +0.3V V+ to V-................................................................-0.3V to +44.0V IN_ or OUT_ .........................................................................44V IN_ Overvoltage with Power On...........................................36V IN_ Overvoltage with Power Off...........................................40V Continuous Current into Any Terminal..............................30mA Peak Current into Any Terminal (pulsed at 1ms, 10% duty cycle).................................70mA Continuous Power Dissipation (TA = +70C) 8-Pin Narrow SO (derate 5.88mW/C above +70C) ....471mW 8-Pin Plastic DIP (derate 9.09mW/C above +70C) .....727mW 8-Pin CERDIP (derate 8.00mW/C above +70C) ...........640mW 18-Pin Wide SO (derate 9.52mW/ C above +70C) .......762mW 18-Pin Plastic DIP (derate 11.11mW/ C above +70C) ...889mW 18-Pin CERDIP (derate 10.53mW/ C above +70C) ......842mW 20-Pin SSOP (derate 11.11mW/C above +70C) ...........640mW Operating Temperature Ranges MAX4506C_A /MAX4607C_ _ .............................0C to +70C MAX4506E_A/MAX4607E_ _ ...........................-40C to +85C MAX4506MJA/MAX4607MJN ........................-55C to +125C Storage Temperature Range .............................-65C to +160C Lead Temperature (soldering, 10sec) .............................+300C
RECOMMENDED OPERATING GUIDELINES
V+ to GND ..............................................................-0.3V to +40V IN_ to OUT_..........................................................40V Differential V- to GND ...............................................................-32V to +0.3V Continuous Current into Any Terminal ..............................30mA V+ to V- ..................................................................................40V Peak Current into Any Terminal IN_........................................................................................40V (pulsed at 1ms, 10% duty cycle) .................................70mA OUT_ ...............................................................................V+ to VNote 1: OUT_ pins are not fault protected. Signals on OUT_ exceeding V+ or V- are clamped by internal diodes. Limit forward-diode current to maximum current rating. Note 2: IN_ pins are fault protected. Signals on IN_ exceeding -36V to +36V may damage the device. These limits apply with power applied to V+ or V-, or 40V with V+ = V- = 0.
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+ = +15V, V- = -15V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 3) PARAMETER ANALOG SWITCH Fault-Free Analog Signal Range (Note 4) Analog Signal-Path Resistance VIN_ V+ = +15V, V- = -15V, VIN_ = 15V VIN_ = 10V, IOUT_ = 1mA C, E, M +25C RON C, E M +25C Signal-Path Resistance Match (Note 6) RON VIN_ = VOUT_ = 10V, IOUT = 1mA C, E M +25C Signal-Path Leakage Current (Note 7) Input Capacitance FAULT PROTECTION Fault-Protected Analog Signal Range Input Signal-Path Leakage Current, Supplies On VIN_ (Notes 2, 3) Applies with power on Applies with power off C, E, M C, E, M +25C IIN_ VIN_= 25V, VOUT_ = open C, E M 2 -36 -40 -20 -200 -10 0.1 36 40 20 200 10 V nA A IOUT_ON CIN VOUT_ = 10V, VIN_ = 10V or floating VIN = 0, f = 1MHz C, E M +25C 1 V65 V+ 100 125 150 7 10 12 V SYMBOL CONDITIONS TA MIN TYP MAX UNITS
-0.5
-20 -400 20
0.5 20 400 pF nA
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Fault-Protected, High-Voltage Signal-Line Protectors
ELECTRICAL CHARACTERISTICS --Dual Supplies (continued)
(V+ = +15V, V- = -15V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 3) PARAMETER Input Signal-Path Leakage Current, Supplies Off Output Clamp Current, Supplies On Output Clamp Resistance, Supplies On Fault Output Turn-On Delay Time (Note 5) Fault Recovery Time (Note 5) POWER SUPPLY Power-Supply Range V+, VMAX4506 I+ MAX4507 Power-Supply Current VIN_ = +15V MAX4506 IMAX4507 C, E, M +25C C, E M +25C C, E M +25C C, E M +25C C, E M -150 -175 -200 -250 -300 -400 -160 A -90 160 8 90 18 150 175 200 250 300 400 A V SYMBOL IIN_ CONDITIONS VIN_= 40V, VOUT_ = open, V+ = 0, V- = 0 VIN_= +25V VIN_= -25V IOUT = 1mA VIN_= +25V VIN_= -25V TA +25C C, E M IOUT_ ROUT_ +25C +25C +25C +25C +25C +25C MIN -20 -500 -10 13 -26 19 -19 0.5 0.4 10 2.5 TYP 0.2 MAX 20 500 10 26 -13 1.0 1.0 UNITS nA A mA k ns s
MAX4506/MAX4507
RL = 10k, VIN_ = 25V RL = 10k, VIN_ = 25V
ELECTRICAL CHARACTERISTICS--Single Supply
(V+ = +12V, V- = -0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 3) PARAMETER ANALOG SWITCH Fault-Free Analog Signal Range (Note 4) Analog Signal-Path Resistance VIN_ V+ = +12V, V- = 0 VIN_ = +12V VIN_ = +10V, IOUT_ = 1mA C, E, M +25C RON C, E M +25C Signal-Path Resistance Match (Note 6) RON VIN_ = +10V, IOUT_ = 1mA C, E M +25C Signal-Path Leakage Current (Note 7) IOUT_(ON) VIN = +10V or floating C, E M 3 0 125 V+ 200 250 300 12 15 20 V SYMBOL CONDITIONS TA MIN TYP MAX UNITS
-0.5
-20 -400
0.05
0.5 20 400 3 nA
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Fault-Protected, High-Voltage Signal-Line Protectors MAX4506/MAX4507
ELECTRICAL CHARACTERISTICS--Single Supply (continued)
(V+ = +12V, V- = -0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 3) PARAMETER FAULT PROTECTION Fault-Protected Analog Signal Range (Notes 4, 5, 9) Input Signal-Path Leakage Current, Supply On (Note 9) VIN_ Applies with power on Applies with power off VIN_= 25V, VOUT_ = 0 C, E, M C, E, M +25C IIN_ C, E M +25C Input Signal-Path Leakage Current, Supply Off (Note 9) Output Clamp Current, Supply On Output Clamp Resistance, Supply On Fault Output Turn-On Delay Time (Note 5) Fault Recovery Time (Note 5) POWER SUPPLY Power-Supply Range V+ MAX4506 Power-Supply Current I+ VIN_ = +12V MAX4507 C, E, M +25C C, E M +25C C, E M Note 3: Note 4: Note 5: Note 6: Note 7: Note 8: Note 9: 17 +9 9 +36 25 30 40 40 60 80 A V IIN_ VIN_= 40V C, E M IOUT_ ROUT_ VIN_= 25V VIN_= 25V RL = 10k, VIN_ = +25V RL = 10k, VIN_ = +25V +25C +25C +25C +25C -36 -40 -20 -200 -10 -20 -500 -10 3 5.5 1.0 10 2.5 0.2 0.2 36 40 20 200 10 20 500 10 10 2.5 V nA A nA A mA k ns s SYMBOL CONDITIONS TA MIN TYP MAX UNITS
The algebraic convention is used in this data sheet; the most negative value is shown in the minimum column. See Fault-Free Analog Signal Range vs. Supply Voltages graph in the Typical Operating Characteristics. Guaranteed by design. RON = RON(MAX) - RON(MIN) Leakage parameters are 100% tested at maximum rated hot temperature and guaranteed by correlation at TA = +25C. Leakage testing for single-supply operation is guaranteed by testing with dual supplies. Guaranteed by testing with dual supplies.
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Fault-Protected, High-Voltage Signal-Line Protectors
Typical Operating Characteristics
(TA = +25C, unless otherwise noted.)
MAX4506/MAX4507
ON-RESISTANCE vs. OUTPUT VOLTAGE (DUAL SUPPLIES)
MAX4506/07 toc01
ON-RESISTANCE vs. OUTPUT VOLTAGE (SINGLE SUPPLY)
MAX4506/07 toc02
ON-RESISTANCE vs. OUTPUT VOLTAGE AND TEMPERATURE (DUAL SUPPLIES)
V+ = +15V V- = -15V TA = +125C TA = +85C TA = +70C 60 40 20 TA = +25C TA = -40C TA = -55C
MAX4506/07 toc03
140 120 100 RON () 80 60 40 20 0 -20 -15 -10 -5 0 VOUT_ (V) 5 10 15 V+ = +18V V- = -18V V+ = +10V V- = -10V V+ = +15V V- = -15V V+ = +8V V- = -8V
250 V+ = +9V 200 V+ = +12V RON ()
V- = 0V
120 100 80 RON ()
150 V+ = +20V V+ = +30V 50 V+ = +36V 0
100
0 0 5 10 15 20 25 30 35 -15 -10 -5 0 VOUT_ (V) 5 10 15 VOUT_ (V)
20
ON-RESISTANCE vs. OUTPUT VOLTAGE AND TEMPERATURE (SINGLE SUPPLY)
MAX4506/07 toc04
OUTPUT CLAMP RESISTANCE SUPPLIES ON
MAX4506/07 toc05
OUTPUT CLAMP CURRENT SUPPLIES ON vs. TEMPERATURE
20 15 10 IOUT (mA) 5 0 -5 -10 -15 -20 -25 V+ = +15V V- = -15V
MAX4506/07 toc06 MAX4506/07 toc09
250
V+ = +12V V- = 0 TA = +125C TA = +85C TA = +70C
0.8 0.7 0.6 ROUT (k) 0.5 0.4 0.3 0.2 0.1
200
V+ = +15V V- = -15V VIN = 25V VIN = +25V VIN = -25V
25
RON ()
150
100
TA = -40C TA = +25C TA = -55C
50
0
0 0 2 4 6 VOUT_ (V) 8 10 12 -55 -35 -15 -5 25 45 65 85 105 125 TEMPERATURE (C)
-55 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
OUTPUT TRANSFER CHARACTERISTICS (DUAL SUPPLIES)
MAX4506/07 toc07
OUTPUT TRANSFER CHARACTERISTICS (SINGLE SUPPLY)
35 OUTPUT CLAMP VOLTAGE (V) 30 25 20 15 10 5 0 V+ = +9V V+ = +15V V+ = +12V V+ = +25V OUTPUT LOAD = 1M V- = 0 V+ = +36V
MAX4506/07 toc08
FAULT-FREE ANALOG SIGNAL RANGE vs. SUPPLY VOLTAGE
20 15 OUTPUT VOLTAGE (V) 10 5 0 -5 -10 -15 -20
20 15 OUTPUT CLAMP VOLTAGE (V) 10 5 0 -5 -10 -15 -20
(V+ = +18V, V- = -18V) (V+ = +15V, V- = -15V) (V+ = +10V, V- = -10V) (V+ = +8V, V- = -8V) INPUT VOLTAGE LINEARLY SWEPT BETWEEN -30V AND +30V (V+ = +8V, V- = -8V) (V+ = +10V, V- = -10V) (V+ = +15V, V- = -15V) (V+ = +18V, V- = -18V) OUTPUT LOAD = 1M -30 -20 -10 0 10 20
40
INPUT VOLTAGE LINEARLY SWEPT BETWEEN 0 AND 35V 0 5 10 15 20 25 30 35 40 INPUT VOLTAGE (V)
30
-20
-15
-10
-5
0
5
10
15
20
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
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Fault-Protected, High-Voltage Signal-Line Protectors MAX4506/MAX4507
Typical Operating Characteristics (continued)
(TA = +25C, unless otherwise noted.)
FAULT-FREE OUTPUT LEAKAGE CURRENT WITH SUPPLIES ON
MAX45506/07 toc10
INPUT FAULT LEAKAGE CURRENT WITH SUPPLIES ON
MAX45506/07 toc11
MAX4506 POWER-SUPPLY CURRENT vs. TEMPERATURE
150 125 100 75 50 25 0 -25 -50 -75 -100 -125 -150 II+ SINGLE SUPPLY +12V V+ = +15V V- = -15V I+
MAX45506/07 toc12
100n 10n LEAKAGE CURRENT (A) 1n 100p 10p 1p 0.1p 0.01p
VOUT = 10
1 100n LEAKAGE CURRENT (A) 10n 1n IIN AT +25V (V+ = +15V, V- = -15V)
IOUT (V+ = +12V, V- = 0)
100p 10p 1p 0.1p IIN AT +25V (V+ = +12V, V - = 0)
-55
-30
-5
20
45
70
95
120 145
SUPPLY CURRENT (A)
IOUT (V+ = +15V, V- = -15V)
-55 -35 -15
5
25
45
65
85 105 125
-55 -35 -15
5
25
45
65
85 105 125
TEMPERATURE (C)
TEMPERATURE (C)
TEMPERATURE (C)
MAX4507 POWER-SUPPLY CURRENT vs. TEMPERATURE
200 150 SUPPLY CURRENT (A) 100 50 0 -50 -100 -150 -200 -250 -55 -35 -15 5 25 45 65 85 105 125 TEMPERATURE (C) II+ SINGLE SUPPLY + 12V I+ V+ = +15V V- = -15V
MAX45506/07 toc13
SUPPLY CURRENT vs. INPUT VOLTAGE
I+
MAX45506/07 toc14
FREQUENCY RESPONSE
0 -10 -20 RESPONSE (dB) -30 -40 -50 -60 -70 -80 CROSSTALK V+ = +15V V- = -15V BANDWIDTH
MAX4506/07 toc15
250
100 80 60 SUPPLY CURRENT (A) 40 20 0 -20 -40 -60 -80 -100 -15
10
I10 5 0 5 INPUT VOLTAGE (V) 10 15
-90 -100 0.01 0.1 1 10 100 1000
FREQUENCY (MHz)
FAULT-FREE SIGNAL PERFORMANCE
MAX45506/07 toc16
INPUT OVERVOLTAGE vs. OUTPUT CLAMPING
MAX45506/07 toc17
FAULT RECOVERY
MAX45506/07 toc18
+15V IN_ 10V/div -15V +15V OUT_ 0V 10V/div -15V 5s/div FAULT-FREE RAIL-TO-RAIL SIGNAL HANDLING WITH 15V SUPPLIES
+25V +16V IN_ 0V +15V -25V 0V OUT_ 0V OUT_ 5V/div 0V V+ = +15V V- = -15V +15V IN_ 5V/div
0V -15V
5s/div 25V OVERVOLTAGE INPUT WITH THE OUTPUT CLAMPED AT 15V
5s/div
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Fault-Protected, High-Voltage Signal-Line Protectors
Pin Description
PIN MAX4506 8-Pin DIP/SO 1, 2, 3 - 4 - 5, 6, 7 8 - MAX4507 18-Pin DIP/SO 1, 2, 3 4-8 9 10-14 15, 16, 17 18 - 20-Pin SSOP 1, 2, 4 5-9 10 11-15 16, 17, 19 20 3, 18 IN1, IN2, IN3 IN4, IN5, IN6, IN7, IN8 VOUT8, OUT7, OUT6, OUT5, OUT4 OUT3, OUT2, OUT1 V+ N.C. Signal Inputs 1, 2, 3 Signal Inputs 4, 5, 6, 7, 8 Negative Supply Voltage Input Signal Outputs 8, 7, 6, 5, 4 Signal Outputs 3, 2, 1 Positive Supply-Voltage Input No Connection. Not internally connected. NAME* FUNCTION
MAX4506/MAX4507
* Connect all unused inputs to a hard voltage within the supply range (e.g., V+, V-, or GND).
Detailed Description
The MAX4506/MAX4507 protect other ICs from overvoltage by clamping its output voltage to the supply rails. If the power supplies to the device are off, the device clamps the output to 0V. The MAX4506/ MAX4507 provide protection for input signals up to 36V with the power supplies on and 40V with the power supplies off. The MAX4506/MAX4507 protect other integrated circuits connected to its output from latching up. Latchup is caused by parasitic SCR(s) within the IC turning on, and can occur when the supply voltage applied to the IC exceeds the specified operating range. Latchup can also occur when signal voltage is applied before the power-supply voltage. When in a latchup state, the circuit draws excessive current and may continue to draw excessive current even after the overvoltage condition is removed. A continuous latchup condition may damage the device permanently. Such "faults" are commonly encountered in modular control systems where power supplies to interconnected modules may be interrupted and reestablished at random. Faults can happen during production testing, maintenance, startup, or a power failure. Figure 1 shows the normal complementary pair (N1 and P1) found in many common analog switches. In addition to these transistors, the MAX4506/MAX4507 also contain comparators and sensing and clamping circuitry to control the state of N1 and P1. During normal opera-
-15V
COMPARATOR
-15V
N3 SENSE SWITCH
N-CHANNEL DRIVER
-V(-15V)
CLAMP N2 N1 OUT CLAMP P2
IN
P3 SENSE SWITCH +15V
P1 +V(+15V) P-CHANNEL DRIVER
+15V
COMPARATOR
Figure 1. Simplified Internal Structure
tion, N1 and P1 remain on with a typical 65 on-resistance between IN and OUT. The on-board comparators and sensing circuitry monitor the input voltage for possible overvoltage faults.
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Fault-Protected, High-Voltage Signal-Line Protectors MAX4506/MAX4507
Two clamp circuits limit the output voltage to within the supply voltages. When the power supplies are off, any input voltage applied at IN turns off both N1 and P1, and OUT is clamped to 0V.
Normal Operation
When power is applied, each protector acts as a resistor in series with the signal path. Any voltage source on the "input" side of the switch will be conducted through the protector to the output (Figure 2). When the output load is resistive, it draws current through the protector. The internal resistance is typically less than 100. High-impedance loads are relatively unaffected by the presence of the MAX4506/MAX4507. The protector's path resistance is a function of the supply voltage and the signal voltage (see Typical Operating Characteristics).
V4 V-
MAX4506
V+ 8 V+
1 IN1 VIN
OUT1
7
ROUT
Fault Protection, Power Off
When power is off (i.e., V+ = V- = 0), the protector is a virtual open circuit. With up to 40V applied to the input pin, the output pin will be 0V.
Figure 2. Application Circuit
+15V
Fault Protection, Power On
A fault condition exists when the voltage on the IN_ exceeds either supply rail. This definition is valid when power is on or off, as well as during all states while power ramps up or down.
MAX4506
V+ 1 IN1 8 10F OUT1 7 100k
Applications Information
Supplying Power Through External ICs
The MAX4506/MAX4507 have low supply currents (<250A), which allows the supply pins to be driven by other active circuitry instead of connected directly to the power sources. In this configuration, the parts can be used as driven fault-protected switches with V+ or V- used as the control pins. For example, with the Vpin grounded, the output of a CMOS gate can drive the V+ pin to turn the device on and off. This can effectively connect and disconnect three (MAX4506) or eight (MAX4507) separate signal lines at once. Ensure that the driving source(s) does not drive the V+ pin more negative than the V- pin. Figure 3 shows a simple turn-on delay that takes advantage of the MAX4506's low power consumption. The two RC networks cause gradual application of power to the MAX4506, which in turn applies the input signals smoothly after the amplifier has stabilized. The
2 IN2
OUT2 6 OP AMP
3 IN3 4 V-
OUT3 5
10F
100k -15V
Figure 3. Turn-On Delay
two diodes discharge the two capacitors rapidly when the power turns off. Note that the IC used to supply power to the MAX4506/MAX4507 must be able to supply enough current to maintain the load voltage at the supply rail in a fault condition.
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Fault-Protected, High-Voltage Signal-Line Protectors
Protectors as Circuit Elements
Each of the protectors in a MAX4506/MAX4507 may be used as a switched resistor, independent of the functions of other elements in the same package. For example, Figure 4 shows a MAX4506 with two of the protectors used to protect the input of an op amp, and the third element used to sequence a power supply. Combining the circuits of Figures 3 and 4 produces a delayed action on the switched +15V, as well as smooth application of signals to the amplifier input. Figure 5 shows MAX4506 used in front of a MAX338 unprotected 1-to-8 multiplexer. With supplies at 15V, VOUT of the MAX4506 clamps to 15V; V OUT of the MAX338 goes to 14V. With supplies off, VOUT goes to 0V while the inputs remain at 25V.
SWITCHED +15V P
Use the MAX4506 with a MAX338 to enhance voltage handling capability (Figure 6). The MAX4506 and MAX338 share almost equal voltage drops in this configuration. For example, applying 40V on pins 1 and 2 of the MAX4506 causes a voltage drop of about 26V across pin 1 of the MAX4506 to pin 4 of the MAX338, and a voltage drop of about 28V across pin 4 of the MAX4506 to pin 8 of the MAX338. Similarly, there is a 26V drop from pin 2 of the MAX4506 to pin 5 of the MAX338. The system's performance exceeds each individual part's specification because of shared voltage drops.
MAX4506/MAX4507
Multiplexer and Demultiplexer
As shown in Figure 7, the MAX4506 can be used in series with the output of a MAX4508 (1-to-8 multiplexer) to act as multiplexer or demultiplexer. The MAX4508 is a fault-protected multiplexer whose inputs are designed to interface with harsh environments; however, its common output is not fault protected if connected to outside signals (i.e., demultiplexer use). If the common output can see fault signals, then it needs to be protected, and the MAX4506 can be added to provide complete protection.
MAX4506
V+ 1 IN1
+15V 8
OUT1 7 100k
2 IN2
OUT2 6 OP AMP +40V VOUT = -14V 1 7 4 8 10k -40V 2 6 5
3 IN3 4 V-
OUT3 5
MAX4506
-15V
MAX338
Figure 4. Power-Supply Sequencing
+3V OV 1 +5V 2 -5V 3 +25V 1 -25V 2 8 +15V 7 4 5 6 7 -15V 4 5 RL 8 AO EN VNO1 MAX338 NO2 NO3 NO4 VOUT A1 16 A2 15 GND 14 V+ 13 +15V NO5 12 NO6 11 NO7 10 NO9 9
Figure 6. SPDT Switch Application
+3V O NEW COM 1 2 1 +5V 2 -15V 3 8 +15V 7 4 5 6 7 -15V 4 5 8 AO EN VA1 16 A2 15 GND 14
NO1 MAX4508 V+ 13 +15V NO2 NO3 NO4 COM NO5 12 NO6 11 NO7 10 NO9 9
MAX4506
3 6
MAX4506
3 6
Figure 5. Protecting a MAX338 with a MAX4506
Figure 7. Multiplexer and Demultiplexer Application Using MAX4506 (or MAX4507) with MAX4508
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Fault-Protected, High-Voltage Signal-Line Protectors MAX4506/MAX4507
As seen in Figure 7, the signal input can now be put into pin 1 of the MAX4506 (new common output for system), and outputs can be taken at MAX4508 pins 4 to 7, and 9 to 12. This is the classic demultiplexer operation. This system now has full protection on both of the multiplexers' inputs and outputs. Note: It is important to use a voltage source of 100mV or less. As shown in Figure 8, this voltage and the VIN voltage form the VOUT voltage. Using higher voltages could cause OUT to go into a fault condition prematurely.
High-Voltage Surge Suppression
These devices are not high-voltage arresters, nor are they substitutes for surge suppressors. However, the MAX4506/MAX4507 can fill a vital gap in systems that use these forms of protection (Figure 9). Although surge suppressors are extremely fast shunt elements, they have very soft current knees. Their clamp voltage must be chosen well above the normal signal levels, because they have excessive leakage currents as the analog signal approaches the knee. This leakage current can interfere with normal operation when signal levels are low or impedance is high. If the clamp voltage is too high, the input can be damaged. Connecting a MAX4506/MAX4507 after a surge suppressor allows the surge-suppressor voltage to be set above the supply voltage (but within the overvoltage limits), dramatically reducing leakage effects (Figure 9). During a surge, the surge suppressor clamps the input voltage roughly to the 10V supplies.
Measuring Path Resistance
Measuring path resistance requires special techniques, since path resistance varies dramatically with the IN and OUT voltages relative to the supply voltages. Conventional ohmmeters should not be used for the following two reasons: 1) the applied voltage and currents are usually not predictable, and 2) the true resistance is a function of the applied voltage, which is dramatically altered by the ohmmeter itself. Autoranging ohmmeters are particularly unreliable. Figure 8 shows a circuit that can give reliable results. This circuit uses a 100mV voltage source, a low-voltage-drop ammeter as the measuring circuit, and an adjustable supply to sweep the analog voltage across its entire range. The ammeter must have a voltage drop of less than one millivolt (up to the maximum test current) for accurate results. A Keithley model 617 electrometer has a suitable ammeter circuit, appropriate ranges, and a built-in voltage source designed for this type of measurement. Find the path resistance by setting the analog voltage, measuring the current, and calculating the path resistance. Repeat the procedure at each analog and supply voltage.
+10V
MAX4506
V+ 100mV A 1 IN1
8
OUT1 7
MAX4506
VIN IN1 ADJUSTABLE ANALOG VOLTAGE 4 VV+ 8 V+ OUT1 VOUT 2 IN2 OUT2 6 OP AMP 3 IN3 4 VOUT3 5
PATH RESISTANCE = 100mv/A SURGE SUPPRESSORS -15V -10V
Figure 8. Path-Resistance Measuring Circuit
10
Figure 9. Surge-Suppression Circuit
______________________________________________________________________________________
Fault-Protected, High-Voltage Signal-Line Protectors
Ordering Information (continued)
PART MAX4507CAP MAX4507CWN MAX4507CPN MAX4507C/D MAX4507EAP MAX4507EWN MAX4507EPN MAX4507MJN TEMP. RANGE 0C to +70C 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C -40C to +85C -55C to +125C PIN-PACKAGE 20 SSOP 18 SO 18 Plastic DIP Dice* 20 SSOP 18 SO 18 Plastic DIP 18 CERDIP**
MAX4506/MAX4507
*Contact factory for dice specifications. **Contact factory for availability.
Chip Topographies
MAX4506
V+ IN1 IN2 IN1
MAX4507
V+ OUT1
OUT2 OUT1 IN3 IN2 0.112" (2.84mm) OUT2 IN3 IN6 OUT6 IN4 OUT4 IN5 OUT5 0.112" (2.84mm) OUT3
V-
OUT3
IN7
IN8 0.071" (1.80mm) VOUT8 0.071" (1.800mm)
OUT7
TRANSISTOR COUNT: 144 (MAX4506) 379 (MAX4507) SUBSTRATE CONNECTED TO V+
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11
Fault-Protected, High-Voltage Signal-Line Protectors MAX4506/MAX4507
Pin Configurations (continued)
TOP VIEW
IN1 1 IN2 2 IN3 3 IN4 4 IN5 5 IN6 6 IN7 7 IN8 8 V- 9 18 V+ 17 OUT1 16 OUT2 15 OUT3 IN1 1 IN2 2 N.C. 3 IN3 4 IN4 5 IN5 6 IN6 7 IN7 8 IN8 9 V- 10 20 V+ 19 OUT1 18 N.C. 17 OUT2
MAX4507
14 OUT4 13 OUT5 12 OUT6 11 OUT7 10 OUT8
MAX4507
16 OUT3 15 OUT4 14 OUT5 13 OUT6 12 OUT7 11 OUT8
SO/DIP SSOP
Package Information
SSOP.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) 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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