19-1415; Rev 1; 8/99 Fault-Protected, High-Voltage Signal-Line Protectors 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® 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 100Ω max and matched within 7Ω, and on-leakage is less than 0.5nA at TA = +25°C. 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 ♦ Overvoltage Protection ±40V with Power Off ±36V with Power On ♦ Open Signal Paths with Power Off ♦ Output Clamps to Either Rail with an Input Overvoltage ♦ Any On Channel Output is Not Affected by an Overvoltage to Any Other Channel ♦ 100Ω max On-Resistance ♦ 10ns Overvoltage Turn-On Delay ♦ No Latchup During Power Sequencing ♦ Rail-to-Rail Signal Handling ♦ 500Ω Output Clamp Resistance During Overvoltage Ordering Information PART TEMP. RANGE MAX4506CSA 0°C to +70°C 8 SO MAX4506CPA 0°C to +70°C 8 Plastic DIP MAX4506C/D 0°C to +70°C Dice* Process-Control Systems MAX4506ESA -40°C to +85°C 8 SO Hot-Insertion Boards/Systems MAX4506EPA MAX4506MJA -40°C to +85°C -55°C to +125°C 8 Plastic DIP 8 CERDIP** Applications Data-Acquisition Systems PIN-PACKAGE Ordering Information continued at end of data sheet. *Contact factory for dice specifications. **Contact factory for availability. Redundant/Backup Systems ATE Equipment Sensitive Instruments Pin Configurations Typical Operating Circuit SWITCHED +15V TOP VIEW P MAX4506 V+ 1 IN1 OUT1 7 2 IN2 OUT2 6 3 IN3 OUT3 5 4 +15V 8 IN1 1 8 V+ 7 OUT1 3 6 OUT2 V- 4 5 OUT3 IN2 2 MAX4506 100k IN3 OP AMP V- SO/DIP -15V Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd. Pin Configurations continued at end of data sheet. ________________________________________________________________ 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 1-800-835-8769. MAX4506/MAX4507 General Description MAX4506/MAX4507 Fault-Protected, High-Voltage Signal-Line Protectors 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 = +70°C) 8-Pin Narrow SO (derate 5.88mW/°C above +70°C) ....471mW 8-Pin Plastic DIP (derate 9.09mW/°C above +70°C) .....727mW 8-Pin CERDIP (derate 8.00mW/°C above +70°C) ...........640mW 18-Pin Wide SO (derate 9.52mW/ °C above +70°C) .......762mW 18-Pin Plastic DIP (derate 11.11mW/ °C above +70°C) ...889mW 18-Pin CERDIP (derate 10.53mW/ °C above +70°C) ......842mW 20-Pin SSOP (derate 11.11mW/°C above +70°C) ...........640mW Operating Temperature Ranges MAX4506C_A /MAX4607C_ _ .............................0°C to +70°C MAX4506E_A/MAX4607E_ _ ...........................-40°C to +85°C MAX4506MJA/MAX4607MJN ........................-55°C to +125°C Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10sec) .............................+300°C 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 = +25°C.) (Note 3) PARAMETER SYMBOL CONDITIONS TA MIN C, E, M V- TYP MAX UNITS V+ V ANALOG SWITCH Fault-Free Analog Signal Range (Note 4) VIN_ V+ = +15V, V- = -15V, VIN_ = ±15V Analog Signal-Path Resistance RON VIN_ = ±10V, IOUT_ = 1mA 65 +25°C 125 M 150 1 +25°C Signal-Path Resistance Match (Note 6) Signal-Path Leakage Current (Note 7) Input Capacitance ∆RON IOUT_ON VIN_ = VOUT_ = ±10V, IOUT = 1mA VOUT_ = ±10V, VIN_ = ±10V or floating CIN VIN = 0, f = 1MHz Fault-Protected Analog Signal Range VIN_ (Notes 2, 3) Input Signal-Path Leakage Current, Supplies On IIN_ VIN_= ±25V, VOUT_ = open 100 C, E 7 C, E 10 M 12 +25°C -0.5 C, E -20 20 M -400 400 +25°C Ω Ω 0.5 20 nA pF FAULT PROTECTION 2 Applies with power on C, E, M -36 36 Applies with power off C, E, M -40 40 +25°C -20 C, E -200 0.1 200 M -10 10 _______________________________________________________________________________________ 20 V nA µA Fault-Protected, High-Voltage Signal-Line Protectors (V+ = +15V, V- = -15V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3) PARAMETER Input Signal-Path Leakage Current, Supplies Off SYMBOL IIN_ Output Clamp Current, Supplies On IOUT_ Output Clamp Resistance, Supplies On ROUT_ CONDITIONS VIN_= ±40V, VOUT_ = open, V+ = 0, V- = 0 TA MIN TYP MAX +25°C -20 0.2 20 C, E -500 500 M -10 VIN_= +25V +25°C 13 19 26 VIN_= -25V +25°C -26 -19 -13 IOUT = 1mA 10 VIN_= +25V +25°C 0.5 1.0 VIN_= -25V +25°C 0.4 1.0 UNITS nA µA mA kΩ ± Fault Output Turn-On Delay Time (Note 5) RL = 10kΩ, VIN_ = ±25V +25°C 10 ns ± Fault Recovery Time (Note 5) RL = 10kΩ, VIN_ = ±25V +25°C 2.5 µs POWER SUPPLY Power-Supply Range V+, V- C, E, M ±8 90 +25°C MAX4506 I+ Power-Supply Current 175 M 200 160 MAX4506 IMAX4507 250 300 C, E 400 M VIN_ = +15V V 150 C, E +25°C MAX4507 ±18 +25°C -150 C, E -175 M -200 +25°C -250 C, E -300 M -400 -90 µA µA -160 ELECTRICAL CHARACTERISTICS—Single Supply (V+ = +12V, V- = -0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3) PARAMETER SYMBOL CONDITIONS TA MIN C, E, M 0 TYP MAX UNITS V+ V ANALOG SWITCH Fault-Free Analog Signal Range (Note 4) VIN_ V+ = +12V, V- = 0 VIN_ = +12V 125 +25°C Analog Signal-Path Resistance RON VIN_ = +10V, IOUT_ = 1mA C, E 250 M 300 +25°C Signal-Path Resistance Match (Note 6) ∆RON VIN_ = +10V, IOUT_ = 1mA IOUT_(ON) VIN = +10V or floating 3 15 M 20 -0.5 0.05 Ω 12 C, E +25°C Signal-Path Leakage Current (Note 7) 200 Ω 0.5 C, E -20 20 M -400 400 nA _______________________________________________________________________________________ 3 MAX4506/MAX4507 ELECTRICAL CHARACTERISTICS —Dual Supplies (continued) MAX4506/MAX4507 Fault-Protected, High-Voltage Signal-Line Protectors ELECTRICAL CHARACTERISTICS—Single Supply (continued) (V+ = +12V, V- = -0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3) PARAMETER SYMBOL CONDITIONS TA MIN TYP MAX Applies with power on C, E, M -36 36 Applies with power off C, E, M -40 40 UNITS FAULT PROTECTION Fault-Protected Analog Signal Range (Notes 4, 5, 9) VIN_ Input Signal-Path Leakage Current, Supply On (Note 9) IIN_ Input Signal-Path Leakage Current, Supply Off (Note 9) IIN_ VIN_= ±25V, VOUT_ = 0 VIN_= ±40V +25°C -20 C, E -200 0.2 200 M -10 10 0.2 20 20 V nA µA +25°C -20 C, E -500 500 M -10 10 µA 3 5.5 10 mA 2.5 kΩ nA Output Clamp Current, Supply On IOUT_ VIN_= 25V +25°C Output Clamp Resistance, Supply On ROUT_ VIN_= ±25V +25°C 1.0 ± Fault Output Turn-On Delay Time (Note 5) RL = 10kΩ, VIN_ = +25V +25°C 10 ns ± Fault Recovery Time (Note 5) RL = 10kΩ, VIN_ = +25V +25°C 2.5 µs POWER SUPPLY Power-Supply Range V+ C, E, M +25°C MAX4506 Power-Supply Current I+ 4 +36 9 +25°C V 25 30 C, E 40 M VIN_ = +12V MAX4507 Note 3: Note 4: Note 5: Note 6: Note 7: Note 8: Note 9: +9 17 40 C, E 60 M 80 µA 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 = +25°C. Leakage testing for single-supply operation is guaranteed by testing with dual supplies. Guaranteed by testing with dual supplies. _______________________________________________________________________________________ Fault-Protected, High-Voltage Signal-Line Protectors ON-RESISTANCE vs. OUTPUT VOLTAGE (SINGLE SUPPLY) 100 200 RON (Ω) 60 V+ = +20V 100 100 V+ = +18V V- = -18V 20 TA = +125°C TA = +85°C TA = +70°C 60 TA = +25°C TA = -40°C 40 V+ = +30V 40 V+ = +15V V- = -15V 80 150 50 MAX4506/07 toc03 V+ = +9V 120 V+ = +12V V+ = +15V V- = -15V 80 V- = 0V RON (Ω) 120 RON (Ω) V+ = +8V V- = -8V V+ = +10V V- = -10V 250 MAX4506/07 toc01 140 ON-RESISTANCE vs. OUTPUT VOLTAGE AND TEMPERATURE (DUAL SUPPLIES) MAX4506/07 toc02 ON-RESISTANCE vs. OUTPUT VOLTAGE (DUAL SUPPLIES) TA = -55°C 20 V+ = +36V 0 -15 -10 -5 0 5 10 15 0 20 5 10 15 20 25 30 35 -15 10 0.4 IOUT (mA) TA = -40°C TA = +25°C 15 VIN = +25V 0.5 VIN = -25V 0.3 -20 6 8 10 12 -25 -55 -35 -15 -5 25 45 65 85 105 125 -55 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) TEMPERATURE (°C) OUTPUT TRANSFER CHARACTERISTICS (DUAL SUPPLIES) OUTPUT TRANSFER CHARACTERISTICS (SINGLE SUPPLY) FAULT-FREE ANALOG SIGNAL RANGE vs. SUPPLY VOLTAGE 10 5 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 = 1MΩ -30 -20 -10 0 10 INPUT VOLTAGE (V) 20 35 30 V+ = +25V 25 20 V+ = +15V 15 V+ = +12V 10 V+ = +9V 5 INPUT VOLTAGE LINEARLY SWEPT BETWEEN 0 AND 35V 0 30 V+ = +36V 0 5 10 15 20 25 INPUT VOLTAGE (V) 30 35 20 MAX4506/07 toc09 (V+ = +10V, V- = -10V) (V+ = +8V, V- = -8V) OUTPUT LOAD = 1MΩ V- = 0 15 OUTPUT VOLTAGE (V) 15 40 MAX4506/07 toc08 (V+ = +18V, V- = -18V) (V+ = +15V, V- = -15V) OUTPUT CLAMP VOLTAGE (V) MAX4506/07 toc07 VOUT_ (V) 20 OUTPUT CLAMP VOLTAGE (V) 4 0 -5 -15 0 2 5 -10 0.2 0.1 0 V+ = +15V V- = -15V 20 MAX4506/07 toc06 0.6 ROUT (kΩ) TA = +85°C V+ = +15V V- = -15V VIN = ±25V 0.7 25 MAX4506/07 toc05 TA = +125°C 0.8 MAX4506/07 toc04 V+ = +12V V- = 0 50 -20 15 OUTPUT CLAMP CURRENT SUPPLIES ON vs. TEMPERATURE TA = -55°C -15 10 OUTPUT CLAMP RESISTANCE SUPPLIES ON 100 -10 5 ON-RESISTANCE vs. OUTPUT VOLTAGE AND TEMPERATURE (SINGLE SUPPLY) TA = +70°C -5 0 VOUT_ (V) 150 0 -5 VOUT_ (V) 200 0 -10 VOUT_ (V) 250 RON (Ω) 0 0 -20 10 5 0 -5 -10 -15 -20 40 -20 -15 -10 -5 0 5 10 15 20 INPUT VOLTAGE (V) _______________________________________________________________________________________ 5 MAX4506/MAX4507 Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) IOUT (V+ = +12V, V- = 0) 10p 10n 1n 100p 1p IIN AT +25V (V+ = +12V, V - = 0) 10p 0.1p 0.1p -30 -5 20 45 70 95 120 145 5 25 45 65 MAX4507 POWER-SUPPLY CURRENT vs. TEMPERATURE SUPPLY CURRENT vs. INPUT VOLTAGE 150 100 50 I+ SINGLE SUPPLY + 12V 0 -50 -100 40 20 0 -20 -40 -250 -100 -55 -35 -15 I+ 60 -80 5 25 45 65 MAX45506/07 toc12 -25 -50 -75 I- 25 45 65 85 105 125 10 BANDWIDTH 0 -10 -20 -30 V+ = +15V V- = -15V -40 CROSSTALK -50 -60 -70 -80 I-15 85 105 125 5 FREQUENCY RESPONSE 80 -200 I+ SINGLE SUPPLY +12V TEMPERATURE (°C) -60 I- 25 0 -55 -35 -15 RESPONSE (dB) V+ = +15V V- = -15V I+ 100 SUPPLY CURRENT (µA) 200 I+ 50 85 105 125 TEMPERATURE (°C) 250 -150 -55 -35 -15 TEMPERATURE (°C) MAX45506/07 toc13 -55 V+ = +15V V- = -15V -100 -125 -150 1p 0.01p 150 125 100 75 MAX4506/07 toc15 100p IIN AT +25V (V+ = +15V, V- = -15V) SUPPLY CURRENT (µA) IOUT (V+ = +15V, V- = -15V) 1n 100n MAX45506/07 toc14 LEAKAGE CURRENT (A) 10n 1µ MAX45506/07 toc11 VOUT = ±10υ MAX4506 POWER-SUPPLY CURRENT vs. TEMPERATURE INPUT FAULT LEAKAGE CURRENT WITH SUPPLIES ON LEAKAGE CURRENT (A) 100n MAX45506/07 toc10 FAULT-FREE OUTPUT LEAKAGE CURRENT WITH SUPPLIES ON SUPPLY CURRENT (µA) MAX4506/MAX4507 Fault-Protected, High-Voltage Signal-Line Protectors TEMPERATURE (°C) -90 10 5 0 5 INPUT VOLTAGE (V) 10 -100 0.01 15 MAX45506/07 toc16 1 10 100 1000 FREQUENCY (MHz) INPUT OVERVOLTAGE vs. OUTPUT CLAMPING FAULT-FREE SIGNAL PERFORMANCE 0.1 FAULT RECOVERY MAX45506/07 toc17 MAX45506/07 toc18 +25V +15V +16V IN_ IN_ 5V/div IN_ 10V/div 0V -15V +15V +15V OUT_ 0V 10V/div -25V 0V OUT_ -15V -15V 5µs/div FAULT-FREE RAIL-TO-RAIL SIGNAL HANDLING WITH ±15V SUPPLIES 6 0V 5µs/div ±25V OVERVOLTAGE INPUT WITH THE OUTPUT CLAMPED AT ±15V +15V 0V OUT_ 5V/div V+ = +15V V- = -15V 0V 5µs/div _______________________________________________________________________________________ Fault-Protected, High-Voltage Signal-Line Protectors PIN MAX4506 MAX4507 NAME* FUNCTION 8-Pin DIP/SO 18-Pin DIP/SO 20-Pin SSOP 1, 2, 3 1, 2, 3 1, 2, 4 IN1, IN2, IN3 – 4–8 5–9 IN4, IN5, IN6, IN7, IN8 4 9 10 V- – 10–14 11–15 OUT8, OUT7, OUT6, OUT5, OUT4 5, 6, 7 15, 16, 17 16, 17, 19 OUT3, OUT2, OUT1 8 18 20 V+ – – 3, 18 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. * 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 -15V COMPARATOR N3 N-CHANNEL DRIVER SENSE SWITCH -V(-15V) CLAMP N2 N1 IN OUT CLAMP P2 P1 P3 SENSE SWITCH +15V +15V +V(+15V) P-CHANNEL DRIVER COMPARATOR Figure 1. Simplified Internal Structure tion, N1 and P1 remain on with a typical 65Ω on-resistance between IN and OUT. The on-board comparators and sensing circuitry monitor the input voltage for possible overvoltage faults. _______________________________________________________________________________________ 7 MAX4506/MAX4507 Pin Description MAX4506/MAX4507 Fault-Protected, High-Voltage Signal-Line Protectors 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 MAX4506 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 100Ω. 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). Fault Protection, Power Off V- 4 V- V+ 1 IN1 OUT1 8 V+ 7 VIN ROUT Figure 2. Application Circuit 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. +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. Applications Information MAX4506 V+ 8 10µF 1 IN1 OUT1 7 2 IN2 OUT2 6 3 IN3 OUT3 5 100k Supplying Power Through External ICs The MAX4506/MAX4507 have low supply currents (<250µA), 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 8 OP AMP 4 V- 10µF 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. _______________________________________________________________________________________ Fault-Protected, High-Voltage Signal-Line Protectors 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 +15V MAX4506 V+ 8 1 IN1 OUT1 7 2 IN2 OUT2 6 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. 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. 100k OP AMP 1 OUT3 5 3 IN3 4 VOUT = -14V +40V 7 4 8 10k V- -40V 2 6 5 MAX4506 MAX338 -15V Figure 4. Power-Supply Sequencing Figure 6. SPDT Switch Application +3V OV 1 AO A1 16 +5V 2 EN -5V 3 V- A2 15 GND 14 +25V 1 8 +15V 4 NO1 MAX338 -25V 2 7 5 NO2 NO5 12 6 NO3 NO6 11 7 NO4 NO7 10 8 VOUT NO9 9 MAX4506 3 -15V 4 6 5 V+ 13 +15V +3V 1 AO A1 16 +5V 2 EN -15V 3 V- A2 15 GND 14 O NEW COM 1 8 +15V 4 NO1 MAX4508 V+ 13 +15V 2 7 5 NO2 NO5 12 6 NO3 NO6 11 7 NO4 NO7 10 8 COM NO9 9 MAX4506 3 -15V 4 6 5 RL Figure 5. Protecting a MAX338 with a MAX4506 Figure 7. Multiplexer and Demultiplexer Application Using MAX4506 (or MAX4507) with MAX4508 _______________________________________________________________________________________ 9 MAX4506/MAX4507 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. MAX4506/MAX4507 Fault-Protected, High-Voltage Signal-Line Protectors 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. 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. 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. +10V MAX4506 V+ A 100mV 8 1 IN1 OUT1 7 2 IN2 OUT2 6 3 IN3 OUT3 5 MAX4506 VIN IN1 OUT1 VOUT OP AMP ADJUSTABLE ANALOG VOLTAGE 4 V- V+ 8 4 V+ V- PATH RESISTANCE = 100mv/A SURGE SUPPRESSORS -15V Figure 8. Path-Resistance Measuring Circuit 10 Figure 9. Surge-Suppression Circuit ______________________________________________________________________________________ -10V Fault-Protected, High-Voltage Signal-Line Protectors PART TEMP. RANGE PIN-PACKAGE MAX4507CAP 0°C to +70°C 20 SSOP MAX4507CWN 0°C to +70°C 18 SO MAX4507CPN 0°C to +70°C 18 Plastic DIP MAX4507C/D 0°C to +70°C Dice* MAX4507EAP MAX4507EWN MAX4507EPN MAX4507MJN -40°C to +85°C -40°C to +85°C -40°C to +85°C -55°C to +125°C 20 SSOP 18 SO 18 Plastic DIP 18 CERDIP** *Contact factory for dice specifications. **Contact factory for availability. Chip Topographies MAX4507 MAX4506 V+ IN1 V+ OUT1 IN2 IN1 OUT2 OUT1 IN3 OUT3 IN2 0.112" (2.84mm) IN4 OUT4 IN5 OUT2 0.112" (2.84mm) OUT5 IN6 IN3 OUT6 V- OUT3 IN7 OUT7 IN8 0.071" (1.80mm) V- TRANSISTOR COUNT: 144 (MAX4506) 379 (MAX4507) SUBSTRATE CONNECTED TO V+ OUT8 0.071" (1.800mm) ______________________________________________________________________________________ 11 MAX4506/MAX4507 Ordering Information (continued) Pin Configurations (continued) TOP VIEW 18 V+ IN1 1 20 V+ IN2 2 17 OUT1 IN2 2 19 OUT1 IN3 3 16 OUT2 N.C. 3 18 N.C. 15 OUT3 IN3 4 14 OUT4 IN4 5 13 OUT5 IN5 6 15 OUT4 IN7 7 12 OUT6 IN6 7 14 OUT5 IN8 8 11 OUT7 IN7 8 13 OUT6 V- 9 10 OUT8 IN8 9 12 OUT7 V- 10 11 OUT8 IN1 1 IN4 4 IN5 5 MAX4507 IN6 6 17 OUT2 MAX4507 16 OUT3 SO/DIP SSOP Package Information SSOP.EPS MAX4506/MAX4507 Fault-Protected, High-Voltage Signal-Line Protectors 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 © 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.