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19-0389; Rev. 2; 9/96
Fault-Protected Analog Multiplexers
_______________General Description
The MAX354/MAX355 fault-protected multiplexers (muxes) use a series N-channel, P-channel, N-channel structure that protects the devices from overvoltage up to 40V beyond the supply rails during power-up, powerdown, and fault conditions. The MAX354/MAX355 also protect sensitive circuit components against voltages near or beyond the normal supplies. The MAX354 single 8-channel mux and the MAX355 dual 4-channel mux protect analog signals while operating from a single 4.5V to 36V supply or 4.5V to 18V dual supplies. These muxes have 350 on-resistance and can be used for demultiplexing as well as multiplexing. Input leakage current is less than 0.5nA at +25C and less than 5nA at +85C. All digital inputs have 0.8V and 2.4V logic thresholds, ensuring both TTL and CMOS logic compatibility without pull-up resistors. Break-before-make operation is guaranteed and power consumption is less than 1.5mW.
____________________________Features
o 350 Max On-Resistance o Improved 2nd Source for MAX358/MAX359 and DG458/DG459 o Pin Compatible with ADG508F/ADG509F o All Switches Off with Supplies Off o On Switch Turns Off with Overvoltage o Output Clamps at 1.5V Below Supply Rails o 0.5nA Max Input Leakage at +25C (5nA at +85C) o No Power-Up Sequencing Required o TTL and CMOS-Logic Compatibility
MAX354/MAX355
______________Ordering Information
PART MAX354CPE MAX354CWE MAX354C/D MAX354EPE MAX354EWE MAX354MJE MAX355CPE MAX355CWE MAX355C/D MAX355EPE MAX355EWE MAX355MJE TEMP. RANGE 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C -55C to +125C 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C -55C to +125C PIN-PACKAGE 16 Plastic DIP 16 Wide SO Dice* 16 Plastic DIP 16 Wide SO 16 CERDIP** 16 Plastic DIP 16 Wide SO Dice* 16 Plastic DIP 16 Wide SO 16 CERDIP**
________________________Applications
Data-Acquisition Systems Industrial and Process Control Avionics ATE Equipment Signal Routing Redundant/Backup Systems
* Dice are tested at TA = +25C only. ** Contact factory for availability.
__________________________________________________________Pin Configurations
TOP VIEW
MAX354
A0 1 EN 2 V- 3 NO1 4 NO2 5 NO3 6 NO4 7 COM 8 LOGIC 16 A1 15 A2 14 GND 13 V+ 12 NO5 11 NO6 10 NO7 9 NO8 A0 1 EN 2 V- 3 NO1A 4 NO2A 5 NO3A 6 NO4A 7 COMA 8
MAX355
16 A1 15 GND LOGIC 14 V+ 13 NO1B 12 NO2B 11 NO3B 10 NO4B 9 COMB
DIP/SO
DIP/SO 1
________________________________________________________________ Maxim Integrated Products
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Fault-Protected Analog Multiplexers MAX354/MAX355
ABSOLUTE MAXIMUM RATINGS
(Voltages referenced to GND, unless otherwise noted.) V+ ...........................................................................-0.3V to +44V V- ............................................................................+0.3V to -44V V+ to V-...................................................................-0.3V to +44V Digital Inputs.........................................(V+ + 0.3V) to (V- - 0.3V) Input Overvoltage with Mux Power On V+ = +15V ....................................................................... +25V V- = -15V ............................................................................-25V Input Overvoltage with Mux Power Off V+ = 0V.............................................................................+40V V- = 0V ...............................................................................-40V Continuous Current into Any Terminal .............................30mA Peak Current into Any Terminal ........................................50mA Continuous Power Dissipation (TA = +70C) Plastic DIP (derate 10.53mW/C above +70C) ...........842mW Wide SO (derate 9.52mW/C above +70C)................ 762mW CERDIP (derate 10.00mW/C above +70C) ...............800mW Operating Temperature Ranges MAX35_C_ _ ........................................................0C to +70C MAX35_E_ _......................................................-40C to +85C MAX35_M_ _ ...................................................-55C to +125C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10sec) ............................ +300C
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, GND = 0V, VAH = VENH = 2.4V, VAL = VENL = 0.8V, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER SWITCH Analog Signal Range Fault-Free Analog Signal Range On-Resistance (Note 2) On-Resistance Matching Between Channels NO-Off Leakage Current (Note 4) VCOM, VNO (Note 1) V+ = +15V, V- = -15V (Note 1) TA = +25C RON INO = 1.0mA, VCOM = 10V INO = 1.0mA, VCOM = 10V (Note 3) VCOM = 10V, VNO = 10V, VEN = 0V VCOM = 10V, VNO = 10V, VEN = 0V ICOM(OFF) VCOM = 10V, VNO = 10V, VEN = 0V TA = TMIN to TMAX TA = +25C TA = TMIN to TMAX TA = +25C TA = TMIN to TMAX TA = +25C MAX354 TA = TMIN to TMAX TA = +25C MAX355 TA = TMIN to TMAX TA = +25C COM-On Leakage Current (Note 4) VCOM = 10V, VNO = 10V, sequence each switch on MAX354 TA = TMIN to TMAX TA = +25C MAX355 TA = TMIN to TMAX C, E M C, E M C, E M C, E M C, E M -0.5 -5.0 -50 -0.5 -25 -100 -0.5 -15 -50 -0.5 -30 -200 -0.5 -15 -100 0.02 0.02 0.02 0.02 0.01 C, E M 7 (V+ - 40) -12 285 (V- + 40) 12 350 450 500 12 15 0.5 5.0 50 0.5 25 100 0.5 15 50 0.5 30 200 0.5 15 100 nA nA nA V V SYMBOL CONDITIONS MIN TYP MAX UNITS
RON
INO(OFF)
COM-Off Leakage Current (Note 4)
ICOM(ON)
2
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Fault-Protected Analog Multiplexers
ELECTRICAL CHARACTERISTICS (continued)
(V+ = +15V, V- = -15V, GND = 0V, VAH = VENH = 2.4V, VAL = VENL = 0.8V, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER FAULT Output Leakage Current (with Overvoltage) Input Leakage Current (with Overvoltage) Input Leakage Current (with Power Supplies Off) DIGITAL LOGIC INPUT Logic High Input Voltage Logic Low Input Voltage Input Current with Input Voltage High Input Current with Input Voltage Low SUPPLY Power-Supply Range Positive Supply Current Negative Supply Current DYNAMIC Transition Time Enable Turn-On Time Enable Turn-Off Time Break-Before-Make Interval Charge Injection Off Isolation tTRANS tON(EN) tOFF(EN) tOPEN VCTE VISO Figure1 Figure 2 Figure 2 Figure 3 CL = 10nF, VS = 0V, RS = 0, Figure 4 TA = +25C TA = TMIN to TMAX TA = +25C TA = TMIN to TMAX TA = +25C TA = TMIN to TMAX TA = +25C TA = +25C 50 100 80 100 80 160 180 250 400 250 400 200 300 ns ns ns ns pC dB I+ IVEN = VA = 5V VEN = VA = 0V TA = +25C TA = TMIN to TMAX TA = +25C TA = TMIN to TMAX 4.5 -300 -500 -1 -100 18 300 500 1 100 V A A VA_H, VENH VA_L, VENL IA_H, IENH IA_L, IENL VA = VEN = 2.4V VA = VEN = 0.8V TA = TMIN to TMAX TA = TMIN to TMAX TA = +25C TA = TMIN to TMAX TA = +25C TA = TMIN to TMAX -1 -5 -1 -5 2.4 0.8 1 5 1 5 V V A A VD = 0V, analog overvoltage = 33V VIN = 25V, VO = 10V VIN = 25V, VEN = VO = 0V, VA0 = VA1 = VA2 = 0V or 5V TA = +25C TA = TMIN to TMAX TA = +25C TA = TMIN to TMAX TA = +25C TA = TMIN to TMAX -5 -2 -0.1 -2 -0.1 -2 0.001 0.001 0.01 5 2 0.1 2 0.1 2 nA A A A SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX354/MAX355
VEN = 0V, RL = 1k, f = 100kHz, TA = +25C Figure 5 VEN = 2.4V, f = 100kHz, VGEN = 1Vp-p, RL = 1k, Figure 6 f = 1MHz, Figure 7 f = 1MHz, VEN = VD = 0V TA = +25C TA = +25C TA = +25C
Crosstalk Between Channels Logic Input Capacitance NO-Off Capacitance
VCT CIN CNO(OFF)
92 2.5 1.6
dB pF pF pF
_______________________________________________________________________________________
3
Fault-Protected Analog Multiplexers MAX354/MAX355
ELECTRICAL CHARACTERISTICS (continued)
(V+ = +15V, V- = -15V, GND = 0V, VAH = VENH = 2.4V, VAL = VENL = 0.8V, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER DYNAMIC (cont'd) COM-Off Capacitance COM-On Capacitance Setting Time (Note 5) CCOM(OFF) CCOM(ON) tSETT f = 1MHz, Figure 7, MAX354 TA = +25C VEN = VD = 0V MAX355 f = 1MHz, Figure 7, MAX354 TA = +25C VEN = VD = 0V MAX355 0.1% 0.01% TA = +25C 11 5 28 14 1 2.5 pF pF s SYMBOL CONDITIONS MIN TYP MAX UNITS
Note 1: When the analog signal exceeds +13.5V or -13.5V, the blocking action of Maxim's gate structure goes into operation. Only leakage currents flow, and the channel on-resistance rises to infinity (see Typical Operating Characteristics). Note 2: Electrical characteristics such as on-resistance will change when power supplies other than 15V are used. Note 3: RON = RON(MAX) - RON(MIN) Note 4: Leakage parameters are 100% tested at maximum rated hot operating temperature, and guaranteed by correlation at +25C. Note 5: Guaranteed by design.
__________________________________________Typical Operating Characteristics
(TA = +25C, unless otherwise noted.)
ON-RESISTANCE vs. ANALOG VOLTAGE
MAX354/5-1a
ON-RESISTANCE vs. ANALOG VOLTAGE
MAX354/5-1b
ON-RESISTANCE vs. VCOM AND TEMPERATURE
V+ = +15V V- = -15V 600 500 RON () A 400 300 200 100 -10 B C D A: B: C: D: +125C +85C +70C +25C
MAX354/5-2
100 10 1 RON (M) V+ = +5V V- = -5V
2000 1800 1600 1400 RON () 1200 1000 800 V+ = +15V V- = -15V V+ = +10V V- = -10V V+ = +5V V- = -5V
700
0.1 0.01 0.001 V+ = +15V V- = -15V
600 400 200 0 -15 -10 -5 0 5 10 15
0.0001 ANALOG VOLTAGE (V)
-15
-10
-5
0
5
10
15
-5
0 VCOM (V)
5
10
ANALOG VOLTAGE (V)
OFF LEAKAGE vs. TEMPERATURE
MAX354-3
ON LEAKAGE vs. TEMPERATURE
MAX354-4
CHARGE INJECTION vs. VCOM
150 100 Qj (pC) 50 0 -50 V+ = +15V V- = -15V
MAX354-5
100 V+ = +15V V- = -15V VNO_ = 10V VCOM_ = 10V
100 V+ = +15V V- = -15V VCOM_ = 10V
200
OFF LEAKAGE (nA)
ICOM(OFF)
ON LEAKAGE (nA)
10
10
1
1
0.1
INO(OFF)
0.1
-100 -150
0.01 -75 -50 -25 0 25 50 75 100 125 TEMPERATURE (C)
0.01 -75 -50 -25 0 25 50 75 100 125 TEMPERATURE (C)
-200 -10 -5 0 VCOM (V) 5 10
4
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Fault-Protected Analog Multiplexers
____________________________Typical Operating Characteristics (continued)
(TA = +25C, unless otherwise noted.)
MAX354/MAX355
SUPPLY CURRENT vs. TEMPERATURE
V+ = +15V V- = -15V VEN = +5V
MAX354-6
FAULT CURRENT vs. FAULT VOLTAGE
10m 1m FAULT CURRENT (A) 100 10 1 100m 10n 1n V+ = +15V V- = -15V V+ = V- = 0V
1000 I+ (VA_ = 5V)
100 I+, I- (A)
I+ (VA_ = 0V) 10
1 I0.1 -75 -50 -25 0 25 50 75 100 125 TEMPERATURE (C)
100p 10p -70 -50 -30 -10 10 30 50 70
FAULT VOLTAGE (V)
______________________________________________________________Pin Description
PIN NAME MAX354 1, 15, 16 -- 2 3 4-7 -- 8 -- 9-12 -- 13 14 MAX355 -- 1, 16 2 3 -- 4-7 -- 8, 9 -- 10-13 14 15 A0, A2, A1 A0, A1 EN VNO1-NO4 NO1A-NO4A COM COMA, COMB NO8-NO5 NO4B-NO1B V+ GND Address Logic Inputs Address Logic Inputs Enable Logic Input. See truth tables. Negative Supply Voltage Input. Connect to GND for single-supply operation. Analog Inputs--bidirectional Analog Inputs--bidirectional "A" switch Analog Output--bidirectional Analog Outputs--bidirectional Analog Inputs--bidirectional Analog Inputs--bidirectional "B" switch Positive Supply Voltage Input Ground FUNCTION
Note: Analog inputs and outputs are electrically identical and completely interchangeable.
_______________________________________________________________________________________
5
Fault-Protected Analog Multiplexers MAX354/MAX355
______________________________________________Test Circuits/Timing Diagrams
+15V V+ A2 A1 A0 NO1 NO2-NO7 +10V
MAX354
VEN 50 -15V +15V V+ A1 A0 EN GND V-
NO8 COM
-10V VOUT 35pF 300 LOGIC INPUT VEN +3V 50% 0V VNO1 SWITCH OUTPUT VOUT
tR < 20ns tF < 20ns
90%
NO1B NO1A-NO4A
+10V
0V 90% VNO8
VEN
MAX355
EN GND
NO4B COMB V300
-10V VOUT 35pF
tTRANS
ON
tTRANS
50 -15V
Figure 1. Transition Time
+15V VEN V+ NO1 NO2-NO8 A0 A1 A2 COM 50 GND V1k -15V +15V VEN EN V+ NO1B +10V SWITCH OUTPUT VOUT 90% VOUT 35pF LOGIC INPUT VEN +3V 50% 0V tON(EN) 0V 10% +10V
EN
MAX354
tR < 20ns tF < 20ns tOFF(EN)
A0 A1 50
NO1A-NO4A NO2B-NO4B, COMA
MAX355
GND COMB V1k -15V VOUT 35pF
Figure 2. Enable Switching Time
6 _______________________________________________________________________________________
Fault-Protected Analog Multiplexers
_________________________________Test Circuits/Timing Diagrams (continued)
+15V VEN V+ NO1-NO8 A0 A1 VA A2 GND 50 -15V V300 COM VOUT 35pF SWITCH OUTPUT VOUT 0V LOGIC INPUT VA +3V 50% 0V +5V 80%
MAX354/MAX355
+2.4V
EN
tR < 20ns tF < 20ns
+10V
MAX354
tOPEN
Figure 3. Break-Before-Make Interval
+15V RS NO VEN VS CHANNEL SELECT EN A0 A1 A2 CL = 1000nF GND VVOUT VOUT VOUT IS THE MEASURED VOLTAGE DUE TO CHARGE TRANSFER ERROR VCTE WHEN THE CHANNEL TURNS OFF. -15V VCTE = VOUT x CL V+ LOGIC INPUT VEN COM VOUT +3V OFF 0V ON OFF
MAX354
Figure 4. Charge Injection
_______________________________________________________________________________________
7
Fault-Protected Analog Multiplexers MAX354/MAX355
_________________________________Test Circuits/Timing Diagrams (continued)
+15V 10nF +15V 10nF
VIN RS = 50
NO1 NO8
V+ R = 1k VIN
NO1 NO2 NO8 COM RL 1k VOUT A0 RG = 50 A1 A2
V+
MAX354
A0 A1 A2 GND EN 10nF -15V OFF ISOLATION = 20log VOUT VIN V-
MAX354
COM RL 1k
VOUT
GND EN 10nF
V-
-15V CROSSTALK = 20log VOUT VIN
Figure 5. Off Isolation
Figure 6. Crosstalk
+15V A2 CHANNEL SELECT A1 A0 GND EN VV+ NO1 NO8 COM f = 1MHz 1MHz CAPACITANCE ANALYZER
MAX354
-15V
Figure 7. NO/COM Capacitance
_______________Detailed Description
Fault-Protection Circuitry
Maxim's MAX354/MAX355 are fully fault protected for continuous input voltages up to 40V, whether or not the V+ and V- power supplies are present. These devices use a "series FET" protection scheme that not only protects the multiplexer output from overvoltage, but also limits the input current to sub-microamp levels. When signal voltages exceed or are within approximately 1.5V of the supply rails, on-resistance increases. This greater on-resistance limits fault currents and output voltage, protecting sensitive circuits and components. The protected output clamps at approximately
1.5V below the supply rails and maintains the correct polarity. There are no glitches or polarity reversals going into or coming out of a fault condition. Figures 8 and 9 show how the series FET circuit protects against overvoltage conditions. When power is off, the gates of all three FETs are at ground. With a -25V input, N-channel FET Q1 is turned on by the +25V gate-tosource voltage. The P-channel device (Q2), however, has +25V VGS and is turned off, thereby preventing the input signal from reaching the output. If the input voltage is +25V, Q1 has a negative VGS, which turns it off. Similarly, only sub-microamp leakage currents can flow from the output back to the input, since any voltage will turn off either Q1 or Q2.
8
_______________________________________________________________________________________
Fault-Protected Analog Multiplexers
Figure 10 shows the condition of an off channel with V+ and V- present. As with Figures 8 and 9, either an Nchannel or a P-channel device will be off for any input voltage from -40V to +40V. The leakage current with negative overvoltages will immediately drop to a few nanoamps at +25C. For positive overvoltages, that fault current will initially be 10A or 20A, decaying over a few seconds to the nanoamp level. The time constant of this decay is caused by the discharge of stored charge from internal nodes and does not compromise the fault-protection scheme. Figure 11 shows the condition of the on channel with V+ and V- present. With input voltages less than 10V, all three FETs are on and the input signal appears at the output. If the input voltage exceeds V+ minus the N-channel threshold voltage (VTN), the N-channel FET will turn off. For voltages more negative than V- minus the P-channel threshold (VTP), the P-channel device will turn off. Since VTN is typically 1.5V and VTP is typically 3V, the multiplexer's output swing is limited to about -12V to +13.5V with 15V supplies.
Switching Characteristics and Charge Injection
Table 1 shows typical charge injection levels versus power-supply voltages and analog input voltage. The charge injection that occurs during switching creates a voltage transient whose magnitude is inversely proportional to the capacitance on the multiplexer output.
MAX354/MAX355
Table 1. MAX354 Charge Injection
Supply Voltage 5V Analog Input Level +2V 0V -2V +5V 0V -5V +10V 0V -10V Injected Charge 52pC 35pC 16pC 105pC 65pC 25pC 180pC 80pC 15pC
10V
15V
Test Conditions: CL, = 1000pF on mux output; the tabulated analog input level is applied to channel 1; channels 2-8 inputs are open circuited. EN = +5V, VA1 = VA2 = 0V, VO is toggled at a 2kHz rate between 0V and 3V. +100pC of charge creates a +100mV step when injected into a 1000pF load capacitance.
-25V OVERVOLTAGE S N-CHANNEL MOSFET IS TURNED ON BECAUSE VGS = +25V
Q1 D G
-25V Q2 S G D S
Q3 D G +25V OVERVOLTAGE S N-CHANNEL MOSFET IS TURNED OFF BECAUSE VGS = -25V Q1 D G S G Q2 D S G Q3 D
P-CHANNEL MOSFET IS OFF
Figure 8. -25V Overvoltage with Multiplexer Power Off
-15V +15V -15V
Figure 9. +25V Overvoltage with Multiplexer Power Off
-15V +15V -15V
-25V OVERVOLTAGE N-CHANNEL MOSFET IS TURNED ON BECAUSE VGS = +10V
Q1
Q2
Q3
-15V FROM DRIVERS
+15V FROM DRIVERS
+25V FORCED ON COMMON OUTPUT LINE BY EXTERNAL CIRCUITRY N-CHANNEL MOSFET IS OFF
+25V OVERVOLTAGE N-CHANNEL MOSFET IS TURNED OFF BECAUSE VGS = -10V
Q1
13.5V Q2
Q3
13.5V OUTPUT N-CHANNEL MOSFET IS ON
VTN = 1.5V +15V FROM DRIVERS -15V FROM DRIVERS
P-CHANNEL MOSFET IS OFF
Figure 10. -25V Overvoltage on an Off Channel with Multiplexer Power Supply On
Figure 11. +25V Overvoltage Input to the On Channel
_______________________________________________________________________________________
9
Fault-Protected Analog Multiplexers MAX354/MAX355
The channel-to-channel switching time is typically 180ns, with about 100ns of break-before-make delay. This 100ns break-before-make delay prevents the input-to-input short that would occur if two input channels were simultaneously connected to the output. In a typical data acquisition system, the dominant delay is not the switching time of the multiplexer, but is the settling time of the amplifiers and S/H. Another limiting factor is the RC time constant of the multiplexer RON plus the signal source impedance multiplied by the load capacitance on the output of the multiplexer. Even with low signal source impedances, 100pF of capacitance on the multiplexer output will approximately double the settling time to 0.01% accuracy.
Digital Interface Levels
The typical digital threshold of both the address lines and the enable pin is 1.6V, with a temperature coefficient of about -3mV/C. This ensures compatibility with 0.8V to 2.4V TTL-logic swings over the entire temperature range. The digital threshold is relatively independent of the supply voltages, moving from 1.6V typical to 1.5V typical as the power supplies are reduced from 15V to 5V. In all cases, the digital threshold is referenced to the GND pin. The digital inputs can also be driven with CMOS-logic levels swinging from either V+ to V- or from V+ to ground. The digital input current is just a few nanoamps of leakage at all input voltage levels, with a guaranteed maximum of 1A.
Operation with Supply Voltages Other than 15V
The main effect of supply voltages other than 15V is the reduction in output signal range. The MAX354 limits the output voltage to about 1.5V below V+ and about 3V above V-. In other words, the output swing is limited to +3.5V to -2V when operating from 5V. The Typical Operating Characteristics show RON for +15V and 5V power supplies. Maxim tests and guarantees the MAX354/MAX355 for operation from 4.5V to 18V supplies. The switching delays are increased by about a factor of 2 at 5V, but break-before-make action is preserved. The MAX354/MAX355 can operate with a single +4.5V to +30V supply, as well as asymmetrical power supplies such as +15V and -5V. The digital threshold remains approximately 1.6V above the GND pin, and the analog characteristics, such as R ON, are determined by the total voltage difference between V+ and V-. Connect V- to 0V when operating with a +4.5V to +30V single supply. The MAX354 digital threshold is relatively independent of the power-supply voltages, going from 1.6V typical when V+ is 15V to 1.5V typical when V+ is 5V. This means that the MAX354/MAX355 operate with standard TTL-logic levels, even with 5V power supplies. In all cases, the threshold of the enable (EN) pin is the same as the other logic inputs.
Operation as a Demultiplexer
The MAX354/MAX355 function as demultiplexers where the input is applied to the output pin, and the input pins are used as outputs. The MAX354/MAX355 provide both break-before-make action and full fault protection when operated as demultiplexers, unlike earlier generations of fault-protected muxes.
Channel-to-Channel Crosstalk, Off-Isolation, and Digital Feedthrough
At DC and low frequencies the channel-to-channel crosstalk is caused by variations in output leakage currents as the off-channel input voltages are varied. The MAX354 output leakage varies only a few picoamps as all seven off inputs are toggled from -10V to +10V. The output voltage change depends on the impedance level at the MAX354 output, which is RON plus the input signal source resistance in most cases, since the load driven by the MAX354 is usually high impedance. For a signal source impedance of 10k or lower, the DC crosstalk exceeds 120dB. Tables 2a and 2b show typical AC crosstalk and offisolation performance. Digital feedthrough is masked by the analog charge injection when the output is enabled. When the output is disabled, the digital feedthrough is virtually unmeasureable, since the digital pins are physically isolated from the analog section by the GND and V- pins. The ground plane formed by these lines is continued onto the MAX354/MAX355 die to provide over 100dB isolation between the digital and analog sections.
10
______________________________________________________________________________________
Fault-Protected Analog Multiplexers MAX354/MAX355
Table 2a. Typical Off-Isolation Rejection Ratio
Frequency One Channel Driven 100kHz 100dB 1MHz 80dB
Table 2b. Typical Crosstalk Rejection Ratio
Frequency RL = 1.5k RL = 10k 100kHz 92dB 76dB 1MHz 72dB 56dB
Test Conditions: V IN = 20Vp-p at the tabulated frequency, RL = 1.5k between OUT and ground, EN = 0V. 20Vp-p VISO = 20log ---------- VOUT (p-p)
Test Conditions: Specified RL connected from OUT to ground, EN = +5V, A0 = A1 = A2 = +5V (Channel 1 selected). 20Vp-p at the tabulated frequency is applied to Channel 2. All other channels are open circuited. Similar crosstalk rejection can be observed between any two channels.
__________________________________________Functional Diagrams/Truth Tables
MAX354
NO1 NO2 NO3 NO4 NO5 NO6 NO7 NO8 DECODERS / DRIVERS COM V+ VGND
MAX354
A2 X 0 0 0 0 1 1 1 1 A0 A1 A2 EN A1 X 0 0 1 1 0 0 1 1 A0 X 0 1 0 1 0 1 0 1 EN 0 1 1 1 1 1 1 1 1 ON SWITCH NONE 1 2 3 4 5 6 7 8
LOGIC "O" VAL +0.8V, LOGIC "1" VAH +2.4V
MAX355
NO1A NO2A NO3A NO4A NO1B NO2B NO3B NO4B
V+
V-
GND
COMA A1 X COMB 0 0 1 1 DECODERS / DRIVERS A0 X 0 1 0 1
MAX355
EN 0 1 1 1 1 ON SWITCH NONE 1 2 3 4
LOGIC "O" VAL +0.8V, LOGIC "1" VAH +2.4V A0 A1 EN
______________________________________________________________________________________
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Fault-Protected Analog Multiplexers MAX354/MAX355
__________________________________________________________Chip Topographies
MAX354
EN VV+ N01 N05 N01A A0 A1 A2 GND VEN A0
MAX355
A1 GND
V+ N.C. N01B
0.130" (3.30mm)
0.130" (3.30mm)
N02 N06
N02A
N02B
N03
N.C.
N03A
N03B
N04
COM N08 0.115" (2.92mm)
N07
N04A
COMA COMB 0.115" (2.92mm)
N04B
TRANSISTOR COUNT: 256 SUBSTRATE CONNECTED TO V+
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) 1996 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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