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19-1902; Rev 1; 8/94
High-Voltage, Fault-Protected Analog Multiplexers
_______________General Description
The MAX378 8-channel single-ended (1-of-8) multiplexer and the MAX379 4-channel differential (2-of-8) multiplexer use a series N-channel/P-channel/N-channel structure to provide significant fault protection. If the power supplies to the MAX378/MAX379 are inadvertently turned off while input voltages are still applied, all channels in the muxes are turned off, and only a few nanoamperes of leakage current will flow into the inputs. This protects not only the MAX378/MAX379 and the circuitry they drive, but also the sensors or signal sources that drive the muxes. The series N-channel/P-channel/N-channel protection structure has two significant advantages over the simple current-limiting protection scheme of the industry's firstgeneration fault-protected muxes. First, the Maxim protection scheme limits fault currents to nanoamp leakage values rather than many milliamperes. This prevents damage to sensors or other sensitive signal sources. Second, the MAX378/MAX379 fault-protected muxes can withstand a continuous 60V input, unlike the first generation, which had a continuous 35V input limitation imposed by power dissipation considerations. All digital inputs have logic thresholds of 0.8V and 2.4V, ensuring both TTL and CMOS compatibility without requiring pull-up resistors. Break-before-make operation is guaranteed. Power dissipation is less than 2mW.
____________________________Features
o o o o o o o o o o Fault Input Voltage 75V with Power Supplies Off Fault Input Voltage 60V with 15V Power Supplies All Switches Off with Power Supplies Off On Channel Turns OFF if Overvoltage Occurs on Input or Output Only Nanoamperes of Input Current Under All Fault Conditions No Increase in Supply Currents Due to Fault Conditions Latchup-Proof Construction Operates from 4.5V to 18V Supplies All Digital Inputs are TTL and CMOS Compatible Low-Power Monolithic CMOS Design
MAX378/MAX379
______________Ordering Information
PART MAX378CPE TEMP. RANGE 0C to +70C PIN-PACKAGE 16 Plastic DIP
________________________Applications
Data Acquisition Systems Industrial and Process Control Systems Avionics Test Equipment Signal Routing Between Systems
MAX378CWG 0C to +70C 24 Wide SO MAX378CJE 0C to +70C 16 CERDIP MAX378C/D 0C to +70C Dice** MAX378EPE -40C to +85C 16 Plastic DIP MAX378EWG -40C to +85C 24 Wide SO MAX378EJE -40C to +85C 16 CERDIP MAX378MJE -55C to +125C 16 CERDIP MAX378MLP -55C to +125C 20 LCC* Ordering Information continued at end of data sheet. * Contact factory for availability. **The substrate may be allowed to float or be tied to V+ (JI CMOS).
__________________________________________________________Pin Configurations
TOP VIEW
A0 1 EN 2 V- 3 IN1 4 IN2 5 IN3 6 IN4 7 OUT 8 16 A1 15 A2 14 GND A0 1 EN 2 V- 3 IN1A 4 IN2A 5 IN3A 6 IN4A 7 OUTA 8 16 A1 15 GND 14 V+
MAX378
13 V+ 12 IN5 11 IN6 10 IN7 9 IN8
MAX379
13 IN1B 12 IN2B 11 IN3B 10 IN4B 9 OUTB
DIP Pin Configurations continued at end of data sheet.
DIP
________________________________________________________________ Maxim Integrated Products
1
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High-Voltage, Fault-Protected Analog Multiplexers MAX378/MAX379
ABSOLUTE MAXIMUM RATINGS
Voltage between Supply Pins ..............................................+44V V+ to Ground ...................................................................+22V V- to Ground......................................................................-22V Digital Input Overvoltage: V+......................................................................+4V VEN, VA V- ........................................................................-4V Analog Input with Multiplexer Power On..............................65V Recommended V+ .....................................+15V Power Supplies V- .......................................-15V Analog Input with Multiplexer Power Off..............................80V Continuous Current, IN or OUT...........................................20mA Peak Current, IN or OUT (Pulsed at 1ms, 10% duty cycle max) ............................40mA Power Dissipation (Note 1) (CERDIP) ................................1.28W Operating Temperature Range: MAX378/379C .....................................................0C to +70C MAX378/379E ..................................................-40C to +85C MAX378/379M ...............................................-55C to +125C Storage Temperature Range .............................-65C to +150C Note 1: Derate 12.8mW/C above TA = +75C
{
{
}
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; VAH (Logic Level High) = +2.4V, VAL (Logic Level Low) = +0.8V, unless otherwise noted.) -55C to +125C MIN TYP MAX STATIC ON Resistance OFF Input Leakage Current rDS(ON) IIN(OFF) VOUT = 10V, IIN = 100A VAL = 0.8V, VAH = 2.4V VIN = 10V, VOUT = VEN = 0.8V (Note 6) VOUT = 10V, VIN = VEN = 0.8V (Note 6) 10V +25C Full +25C Full 10V MAX378 MAX379 +25C Full Full +25C Full Full Full Full -50 -1.0 -200 -100 -10 -600 -300 -15 -50 0.1 0.1 2.0 3.0 -0.5 0.03 3.0 4.0 0.5 50 1.0 200 100 10 600 300 +15 50 -50 -2.0 -200 -100 -20 -600 -300 -15 -50 0.1 0.1 2.0 3.0 -1.0 0.03 3.5 4.0 1.0 50 2.0 200 100 20 600 300 +15 50 V nA nA nA k nA 0C to +70C and -40C to +85C MIN TYP MAX
PARAMETER
SYMBOL
CONDITIONS
TEMP
UNITS
OFF Output Leakage Current
IOUT(OFF)
ON Channel Leakage Current Analog Signal Range Differential OFF Output Leakage Current FAULT Output Leakage Current (with Input Overvoltage) Input Leakage Current (with Overvoltage) Input Leakage Current (with Power Supplies Off) CONTROL Input Low Threshold Input High Threshold Input Leakage Current (High or Low) 2
IOUT(ON) VAN IDIFF
VIN(ALL) = VOUT = 10V VAH = VEN = 2.4V MAX378 VAL = 0.8V (Note 5) MAX379 (Note 2) MAX379 only (Note 6)
IOUT(OFF) IIN(OFF) IIN(OFF)
VOUT = 0V, VIN = 60V (Notes 3, 4) VIN = 60V, VOUT = 10V (Notes 3, 4) VIN = 75V, VEN = VOUT = 0V A0 = A1 = A2 = 0V or 5V (Note 4) (Note 4) VA = 5V or 0V (Note 5)
+25C Full +25C +25C
20 10 25 10
20 20 40 20
nA A A A
VAL VAH IA
Full Full Full 2.4 -1.0
0.8 2.4 1.0 -1.0
0.8
V V
1.0
A
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High-Voltage, Fault-Protected Analog Multiplexers
ELECTRICAL CHARACTERISTICS (continued)
(V+ = +15V, V- = -15V; VAH (Logic Level High) = +2.4V, VAL (Logic Level Low) = +0.8V, unless otherwise noted.) -55C to +125C MIN TYP MAX DYNAMIC Access Time Break-Before-Make Delay (Figure 2) Enable Delay (ON) Enable Delay (OFF) Settling Time (0.1%) (0.01%) "OFF Isolation" Channel Input Capacitance Channel Output Capacitance Digital Input Capacitance Input to Output Capacitance SUPPLY Positive Supply Current Negative Supply Current Power-Supply Range for Continuous Operation I+ IVOP VEN = 0.8V or 2.4V All VA = 0V or 5V VEN = 0.8V or 2.4V All VA = 0V or 5V (Note 7) +25C Full +25C Full +25C 4.5 0.1 0.3 0.01 0.02 0.6 0.7 0.1 0.2 18 4.5 0.2 0.5 0.01 0.02 1.0 1.0 0.1 0.1 18 mA mA V tA tON-tOFF tON(EN) tOFF(EN) tSETT OFF(ISO) CIN(OFF) COUT(OFF) CA CDS(OFF) Figure 1 VEN = +5V, VIN = 10V A0, A1, A2 strobed Figure 3 Figure 3 +25C +25C +25C Full +25C Full +25C VEN = 0.8V, RL = 1k, CL = 15pF +25C V = 7VRMS, f = 100kHz +25C MAX378 +25C MAX379 +25C +25C 50 1.2 3.5 68 5 25 12 5 0.1 50 300 25 0.5 200 400 750 1000 500 1000 1.2 3.5 68 5 25 12 5 0.1 300 1000 1.0 25 0.5 200 400 1000 1500 1.0 s ns ns ns s dB pF pF pF pF 0C to +70C and -40C to +85C MIN TYP MAX
MAX378/MAX379
PARAMETER
SYMBOL
CONDITIONS
TEMP
UNITS
Note 2: When the analog signal exceeds +13.5V or -12V, the blocking action of Maxim's gate structure goes into operation. Only leakage currents flow and the channel ON resistance rises to infinity. Note 3: The value shown is the steady-state value. The transient leakage is typically 50A. See Detailed Description. Note 4: Guaranteed by other static parameters. Note 5: Digital input leakage is primarily due to the clamp diodes. Typical leakage is less than 1nA at +25C. Note 6: Leakage currents not tested at TA = cold temp. Note 7: Electrical characteristics, such as ON Resistance, will change when power supplies other than 15V are used.
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High-Voltage, Fault-Protected Analog Multiplexers MAX378/MAX379
__________________________________________Typical Operating Characteristics
INPUT LEAKAGE vs. INPUT VOLTAGE WITH V+ = V- = 0V
MAX378-1
OFF CHANNEL LEAKAGE CURRENT vs. INPUT VOLTAGE WITH 15V SUPPLIES
MAX378-2
OUTPUT LEAKAGE CURRENT vs. OFF CHANNEL OVERVOLTAGE WITH 15V SUPPLIES
MAX378-3
1m 100 INPUT CURRENT (A) 10 OPERATING RANGE
100 10 1 IIN(OFF) (A) 100n +60V -60V 10n 1n 100p OPERATING RANGE
10n
1n IOUT(OFF) (A) OPERATING RANGE
1 100n 10n 1n 100p
100p
10p
+80V
-80V
10p 1p -120 1p -120
10p -100
-50
0 VIN (V)
50
100
-60
0 VIN (V)
60
120
-60
0 VIN(OFF) (V)
60
+60V 120
DRAIN-SOURCE ON-RESISTANCE vs. ANALOG INPUT VOLTAGE
+3.5V 6 +13V 5 RDS(ON) (k) 4 3 2 5V SUPPLIES +13V 15V SUPPLIES +4V
MAX3784
7
NOTE: Typical RDS(ON) match @ +10V Analog in (15V supplies) = 2% for lowest to highest R DS(ON) channel; @ -10V Analog in, match = 3%.
1 0 -15 -10 -5 0 5 10 15 20 ANALOG INPUT (V)
MAX378: VAH = 3.0V 50%
ADDRESS DRIVE (VA) 0V VA
A2 IN1 IN2 A1 +VAH 50 A0 EN GND 10V
MAX378 IN2-IN7
IN8 OUT 10M 14pF 10V PROBE
+10V OUTPUT A 90% tA -10V
Figure 1. Access Time vs. Logic Level (High)
4 _______________________________________________________________________________________
-60V
High-Voltage, Fault-Protected Analog Multiplexers MAX378/MAX379
MAX358: VAH = 3.0V ADDRESS DRIVE (VA) VA 2.4V 50% 50% OUTPUT 50
A2 IN1 IN2 A1 A0 EN GND 1k 12.5pF +5V
0V
MAX378* IN2-IN7
IN8 OUT VOUT
tOPEN *SIMILAR CONNECTION FOR MAX379
Figure 2. Break-Before-Make Delay (tOPEN)
MAX378: VAH = 3.0V ENABLE DRIVE 50% 0V
A2
IN1
+10V
A1 A0
MAX378* IN2-IN7
90%
OUTPUT 90%
VA 50
EN GND
OUT 1k 12.5pF
tON(EN) tOFF(EN) *SIMILAR CONNECTION FOR MAX379
Figure 3. Enable Delay (tON(EN), tOFF(EN))
+5V
+15V V+5V or 0V
0V V-
A0 A1 A2 EN I 60V IN1 IN8 V 10V ANALOG SIGNAL
A0 A1 A2 EN OUT I 10k 75V IN1
MAX378
MAX378
OUT V0V GND 10k
V-15V
GND
Figure 4. Input Leakage Current (Overvoltage)
Figure 5. Input Leakage Current (with Power Supplies OFF)
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High-Voltage, Fault-Protected Analog Multiplexers MAX378/MAX379
Truth Table--MAX378
A2 X 0 0 0 0 1 1 1 1 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
+15V THERMOCOUPLE STRAIN GUAGE 4-20mA LOOP TRANSMITTER V+
Truth Table--MAX379
ON SWITCH NONE 1 2 3 4 5 6 7 8 A1 X 0 0 1 1 A0 X 0 1 0 1 EN 0 1 1 1 1 ON SWITCH NONE 1 2 3 4
Note: Logic "0" = VAL 0.8V, Logic "1" = VAH 2.4V
IN1 IN2 IN3
OUT
+15V
MAX420
-15V +15V 1M
IN4 IN5 IN6 +10V GAIN REFERENCE ZERO REFERENCE IN7 IN8
MAX378
V+ IN1 IN2 OUT 100k
V-15V
GND
DG508A MAX358 OR MAX378
V-15V GND
10k IN3 IN4 IN5 111 1k
Figure 6. Typical Data Acquisition Front End
_______________Typical Applications
Figure 6 shows a typical data acquisition system using the MAX378 multiplexer. Since the multiplexer is driving a high-impedance input, its error is a function of its own resistance (RDS(ON)) times the multiplexer leakage current (IOUT(ON)) and the amplifier bias current (IBIAS): VERR = RDS(ON) x (IOUT(ON) + IBIAS (MAX420)) = 2.0k x (2nA + 30pA) = 18.0V maximum error In most cases, this error is low enough that preamplification of input signals is not needed, even with very low-level signals such as 40V/C from type J thermocouples.
6
In systems with fewer than eight inputs, an unused channel can be connected to the system ground reference point for software zero correction. A second channel connected to the system voltage reference allows gain correction of the entire data acquisition system as well. A MAX420 precision op amp is connected as a programmable-gain amplifier, with gains ranging from 1 to 10,000. The guaranteed 5V unadjusted offset of the MAX420 maintains high signal accuracy, while programmable gain allows the output signal level to be scaled to the optimum range for the remainder of the data acquisition system, normally a Sample/Hold and A/D. Since the gain-changing multiplexer is not connected to the external sensors, it can be either a DG508A multiplexer or the fault-protected MAX358 or MAX378.
_______________________________________________________________________________________
High-Voltage, Fault-Protected Analog Multiplexers
Input switching, however, must be done with a faultprotected MAX378 multiplexer, to provide the level of protection and isolation required with most data acquisition inputs. Since external signal sources may continue to supply voltage when the multiplexer and system power are turned off, non-fault-protected multiplexers, or even first-generation fault-protected devices, will allow many milliamps of fault current to flow from outside sources into the multiplexer. This could result in damage to either the sensors or the multiplexer. A nonfault-protected multiplexer will also allow input overvoltages to appear at its output, perhaps damaging Sample/Holds or A/Ds. Such input overdrives may also cause input-to-input shorts, allowing the high current output of one sensor to possibly damage another. The MAX378 eliminates all of the above problems. It not only limits its output voltage to safe levels, with or without power applied (V+ and V-), but also turns all channels off when power is removed. This allows it to draw only sub-microamp fault currents from the inputs, and maintain isolation between inputs for continuous input levels up to 75V with power supplies off.
MAX378/MAX379
+60V OVERVOLTAGE N-CHANNEL MOSFET IS TURNED OFF BECAUSE VGS = -60V
Q1 S G D S
Q2 D G S
Q3 D G
Figure 8. +60V Overvoltage with Multiplexer Power OFF
-15V
+15V
_______________Detailed Description
Fault Protection Circuitry
The MAX378/MAX379 are fully fault protected for continuous input voltages up to 60V, whether or not the V+ and V- power supplies are present. These devices use a "series FET" switching scheme which not only protects the multiplexer output from overvoltage, but also limits the input current to sub-microamp levels. Figures 7 and 8 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 -60V input, N-channel FET Q1 is turned on by the +60V gate-60V OVERVOLTAGE N-CHANNEL MOSFET IS TURNED OFF BECAUSE VGS = +45V Q1 -60V Q2
-15V +60V FORCED ON COMMON OUTPUT LINE BY EXTERNAL CIRCUITRY Q3
-15V FROM DRIVERS P-CHANNEL MOSFET IS OFF
+15V FROM DRIVERS
N-CHANNEL MOSFET IS OFF
Figure 9. -60V Overvoltage on an OFF Channel with Multiplexer Power Supply ON
-15V
+15V
-15V
-60V OVERVOLTAGE N-CHANNEL MOSFET IS TURNED ON BECAUSE VGS = +60V
Q1 S G D
-60V Q2 D S G
Q3 S G D
+60V OVERVOLTAGE N-CHANNEL MOSFET IS TURNED ON BECAUSE VGS = -45V
Q1
+13.5V Q2
Q3
+13.5V OUTPUT
VTN = +1.5V +15V FROM DRIVERS -15V FROM DRIVERS N-CHANNEL MOSFET IS ON
P-CHANNEL MOSFET IS OFF
Figure 7. -60V Overvoltage with Multiplexer Power OFF
Figure 10. +60V Overvoltage Input to the ON Channel
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High-Voltage, Fault-Protected Analog Multiplexers
to-source voltage. The P-channel device (Q2), however, has +60V VGS and is turned off, thereby preventing the input signal from reaching the output. If the input voltage is +60V, 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. Figure 9 shows the condition of an OFF channel with V+ and V- present. As with Figures 7 and 8, either an N-channel or a P-channel device will be off for any input voltage from -60V to +60V. The leakage current with negative overvoltages will immediately drop to a few nanoamps at +25C. For positive overvoltages, that fault current will initially be 40A or 50A, 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 10 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 Nchannel threshold voltage (VTN), then the N-channel FET will turn off. For voltages more negative than Vminus 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. The Typical Operating Characteristics graphs show typical leakage vs. input voltage curves. Although the maximum rated input of these devices is 65V, the MAX378/MAX379 typically have excellent performance up to 75V, providing additional margin for the unknown transients that exist in the real world. In summary, the MAX378/MAX379 provide superior protection from all fault conditions while using a standard, readily produced junction-isolated CMOS process.
MAX378/MAX379
ly connected to the output. In a typical data acquisition system, such as in Figure 6, the dominant delay is not the switching time of the MAX378 multiplexer, but is the settling time of the following amplifiers and S/H. Another limiting factor is the RC time constant of the multiplexer RDS(ON) 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.
Operation with Supply Voltage Other than 15V
The main effect of supply voltages other than 15V is the reduction in output signal range. The MAX378 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 graphs show typical RDS(ON), for 15V, 10V, and 5V power supplies. Maxim tests and guarantees the MAX378/MAX379 for operation from 4.5V to 18V supplies. The switching delays are increased by about a factor of 2 at 5V, but breakbefore-make action is preserved. The MAX378/MAX379 can be operated with a single +9V to +22V supply, as well as asymmetrical power supplies such as +15V and -5V. The digital threshold will remain approximately 1.6V above GND and the analog characteristics such as RDS(ON) are determined by the total voltage difference between V+ and V-. Connect V- to 0V when operating with a +9V to +22V single supply. This means that the MAX378/MAX379 will operate with standard TTL-logic levels, even with 5V power supplies. In all cases, the threshold of the EN pin is the same as the other logic inputs.
Table 1a. MAX378 Charge Injection
Supply Voltage Analog Input Level +1.7V 0V -1.7V +5V 0V -5V +10V 0V -10V Injected Charge +100pC +70pC +45pC +200pC +130pC +60pC +500pC +180pC +50pC
Switching Characteristics and Charge Injection
Table 1 shows typical charge-injection levels vs. power-supply voltages and analog input voltage. Note that since the channels are well matched, the differential charge injection for the MAX379 is typically less than 5pC. The charge injection that occurs during switching creates a voltage transient whose magnitude is inversely proportional to the capacitance on the multiplexer output. The channel-to-channel switching time is typically 600ns, with about 200ns of break-before-make delay. This 200ns break-before-make delay prevents the input-to-input short that would occur if two input channels were simultaneous8
5V
10V
15V
Test Conditions: CL = 1000pF on multiplexer output; the tabulated analog input level is applied to channel 1; channels 2 through 8 are open circuited. EN = +5V, A1 = A2 = 0V, A0 is toggled at 2kHz rate between 0V and 3V. +100pC of charge creates a +100mV step when injected into a 1000pF load capacitance.
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High-Voltage, Fault-Protected Analog Multiplexers
Table 1b. MAX379 Charge Injection
Injected Charge Supply Voltage Analog Input Level +1.7V 0V -1.7V +5V 0V -5V +10V 0V -10V Out A +105pC +73pC +48pC +215pC +135pC +62pC +525pC +180pC +55pC Out B +107pC +74pC +50pC +220pC +139pC +63pC +530pC +185pC +55pC Differential A-B -2pC -1pC -2pC -5pC -4pC -1pC -5pC -5pC 0pC
5V
10V
15V
Test Conditions: CL = 1000pF on Out A and Out B; the tabulated analog input level is applied to inputs 1A and 1B; channels 2 through 4 are open circuited. EN = +5V, A1 = 0V, A0 is toggled from 0V to 3V at a 2kHz rate.
rents as the off-channel input voltages are varied. The MAX378 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 MAX378 output, which is RDS(ON) plus the input signal source resistance in most cases, since the load driven by the MAX378 is usually a high impedance. For a signal source impedance of 10k or lower, the DC crosstalk exceeds 120dB. Table 2 shows typical AC crosstalk and off-isolation 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 unmeasurable, 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 MAX378/MAX379 die to provide over 100dB isolation between the digital and analog sections.
MAX378/MAX379
Digital Interface Levels
The typical digital threshold of both the address lines and the EN 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 GND. The digital inputs can also be driven with CMOS-logic levels swinging from either V+ to V- or from V+ to GND. The digital input current is just a few nanoamps of leakage at all input voltage levels, with a guaranteed maximum of 1A. The digital inputs are protected from ESD by a 30V zener diode between the input and V+, and can be driven 4V beyond the supplies without drawing excessive current.
Table 2a. Typical Off-Isolation Rejection Ratio
Frequency One Channel Driven All Channels Driven 100kHz 500kHz 1MHz
74dB 64dB
72dB 48dB
66dB 44dB
Test Conditions: V IN = 20VP-P at the tabulated frequency, RL = 1.5k between OUT and GND, EN = 0V. 20VP-P OIRR = 20 Log ____________ VOUT (P-P)
Operation as a Demultiplexer
The MAX378/MAX379 will function as a demultiplexer, where the input is applied to the OUT pin, and the input pins are used as outputs. The MAX378/MAX379 provide both break-before-make action and full fault protection when operated as a demultiplexer, unlike earlier generations of fault-protected multiplexers.
Table 2b. Typical Crosstalk Rejection Ratio
Frequency FL = 1.5k RL = 10k 100kHz 500kHz 1MHz
70dB 62dB
68dB 46dB
64dB 42dB
Channel-to-Channel Crosstalk, Off Isolation, and Digital Feedthrough
At DC and low frequencies, channel-to-channel crosstalk is caused by variations in output leakage cur-
Test Conditions: Specified RL connected from OUT to GND, 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.
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High-Voltage, Fault-Protected Analog Multiplexers MAX378/MAX379
_____________________________________________Pin Configurations (continued)
TOP VIEW
A0 1 EN 2 N.C. 3 N.C. 4 V- 5 IN1 6 IN2 7 IN3 8 IN4 9 N.C. 10 N.C. 11 OUT 12
24 A1 23 A2 22 GND 21 N.C.
A0 1 EN 2 N.C. 3 N.C. 4 V- 5 IN1A 6 IN2A 7 IN3A 8
24 A1 23 N.C. 22 GND 21 N.C.
MAX378
20 V+ 19 IN5 18 IN6 17 N.C. 16 IN7 15 N.C. 14 N.C. 13 IN8
MAX379
20 V+ 19 IN1B 18 IN2B 17 IN3B 16 IN4B 15 N.C. 14 N.C. 13 OUTB
IN4A 9 N.C. 10 N.C. 11 OUTA 12
SO
SO
1 N.C.
1 N.C.
V- 4 IN1 5 N.C. 6 IN2 7 IN3 8
18 GND 17 V+
V- 4 IN1A 5 N.C. 6 IN2A 7 IN3A 8
19 GND
2 A0
2 A0
20 A1
19 A2
20 A1
3 EN
3 EN
18 V+ 17 IN1B
MAX378
16 N.C. 15 IN5 14 IN6
MAX379
16 N.C. 15 IN2B 14 IN3B
OUT 10
N.C. 11
IN8 12
IN7 13
OUTA 10
N.C. 11
OUTB 12
LCC
IN4A
LCC
10
______________________________________________________________________________________
IN4B 13
9
IN4
9
High-Voltage, Fault-Protected Analog Multiplexers
_Ordering Information (continued)
PART MAX379CPE MAX379CWG MAX379CJE MAX379C/D MAX379EPE MAX379EWG MAX379EJE MAX379MJE MAX379MLP 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 -55C to +125C PIN-PACKAGE 16 Plastic DIP 24 Wide SO 16 CERDIP Dice** 16 Plastic DIP 24 Wide SO 16 CERDIP 16 CERDIP 20 LCC*
_________________Chip Topographies
MAX378
IN8 OUT IN7 IN4
MAX378/MAX379
IN7
IN3 0.229" (5.816mm)
* Contact factory for availability. **The substrate may be allowed to float or be tied to V+ (JI CMOS).
IN6
IN2
IN5 V+
IN1 V-
GND A2 A1 A0 EN
0.151" (3.835mm) NOTE: Connect substrate to V+ or leave it floating.
MAX379
OUTB OUTA IN4B IN4A
IN3B
IN3A 0.229" (5.816mm)
IN2B
IN2A
IN1B V+
IN1A V-
GND A1 A0 EN
0.151" (3.835mm) NOTE: Connect substrate to V+ or leave it floating.
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11
High-Voltage, Fault-Protected Analog Multiplexers MAX378/MAX379
________________________________________________________Package Information
DIM INCHES MAX MIN 0.104 0.093 0.012 0.004 0.019 0.014 0.013 0.009 0.299 0.291 0.050 0.419 0.394 0.050 0.016 MILLIMETERS MIN MAX 2.35 2.65 0.10 0.30 0.35 0.49 0.23 0.32 7.40 7.60 1.27 10.00 10.65 0.40 1.27
D 0- 8 A e B
0.101mm 0.004in.
A1
C
L
A A1 B C E e H L
DIM PINS
E
H
Wide SO SMALL-OUTLINE PACKAGE (0.300 in.)
D D D D D
16 18 20 24 28
INCHES MIN MAX 0.398 0.413 0.447 0.463 0.496 0.512 0.598 0.614 0.697 0.713
MILLIMETERS MIN MAX 10.10 10.50 11.35 11.75 12.60 13.00 15.20 15.60 17.70 18.10
21-0042A
D1
DIM A A1 A2 A3 B B1 C D D1 E E1 e eA eB L
E D A3 A A2 E1
INCHES MAX MIN 0.200 - - 0.015 0.150 0.125 0.080 0.055 0.022 0.016 0.065 0.050 0.012 0.008 0.765 0.745 0.030 0.005 0.325 0.300 0.280 0.240 0.100 BSC 0.300 BSC 0.400 - 0.150 0.115 15 0
MILLIMETERS MIN MAX - 5.08 0.38 - 3.18 3.81 1.40 2.03 0.41 0.56 1.27 1.65 0.20 0.30 18.92 19.43 0.13 0.76 7.62 8.26 6.10 7.11 2.54 BSC 7.62 BSC - 10.16 2.92 3.81 0 15
21-587A
L A1 e B
C B1 eA eB
16-PIN PLASTIC DUAL-IN-LINE PACKAGE
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
12 __________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 (c) 1994 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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