MAXIM MAX354MJE

19-0389; Rev. 2; 9/96
Fault-Protected Analog Multiplexers
____________________________Features
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.
♦ 350Ω Max On-Resistance
♦ Improved 2nd Source for MAX358/MAX359 and
DG458/DG459
♦ Pin Compatible with ADG508F/ADG509F
♦ All Switches Off with Supplies Off
♦ On Switch Turns Off with Overvoltage
♦ Output Clamps at 1.5V Below Supply Rails
♦ 0.5nA Max Input Leakage at +25°C (5nA at +85°C)
♦ No Power-Up Sequencing Required
♦ TTL and CMOS-Logic Compatibility
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 350Ω on-resistance
and can be used for demultiplexing as well as multiplexing. Input leakage current is less than 0.5nA at
+25°C and less than 5nA at +85°C.
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.
______________Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
MAX354CPE
0°C to +70°C
16 Plastic DIP
MAX354CWE
MAX354C/D
MAX354EPE
MAX354EWE
MAX354MJE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
16 Wide SO
Dice*
16 Plastic DIP
16 Wide SO
16 CERDIP**
Data-Acquisition Systems
MAX355CPE
0°C to +70°C
16 Plastic DIP
Industrial and Process Control
MAX355CWE
MAX355C/D
MAX355EPE
MAX355EWE
MAX355MJE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
16 Wide SO
Dice*
16 Plastic DIP
16 Wide SO
16 CERDIP**
________________________Applications
Avionics
ATE Equipment
Signal Routing
Redundant/Backup Systems
* Dice are tested at TA = +25°C only.
** Contact factory for availability.
__________________________________________________________Pin Configurations
TOP VIEW
MAX354
A0 1
EN 2
V- 3
LOGIC
MAX355
16 A1
A0 1
15 A2
EN 2
14 GND
V- 3
16 A1
15 GND
LOGIC
14 V+
NO1 4
13 V+
NO1A 4
13 NO1B
NO2 5
12 NO5
NO2A 5
12 NO2B
NO3 6
11 NO6
NO3A 6
11 NO3B
NO4 7
10 NO7
NO4A 7
10 NO4B
COM 8
9
NO8
COMA 8
9
DIP/SO
COMB
DIP/SO
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
MAX354/MAX355
_______________General Description
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 = +70°C)
Plastic DIP (derate 10.53mW/°C above +70°C) ...........842mW
Wide SO (derate 9.52mW/°C above +70°C)................ 762mW
CERDIP (derate 10.00mW/°C above +70°C) ...............800mW
Operating Temperature Ranges
MAX35_C_ _ ........................................................0°C to +70°C
MAX35_E_ _......................................................-40°C to +85°C
MAX35_M_ _ ...................................................-55°C to +125°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10sec) ............................ +300°C
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
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
(V+ - 40)
(V- + 40)
V
-12
12
V
SWITCH
Analog Signal Range
Fault-Free Analog
Signal Range
On-Resistance
(Note 2)
On-Resistance Matching
Between Channels
NO-Off Leakage Current
(Note 4)
(Note 1)
VCOM, VNO
V+ = +15V, V- = -15V (Note 1)
TA = +25°C
RON
∆RON
INO = 1.0mA, VCOM = ±10V
INO = 1.0mA, VCOM = ±10V
(Note 3)
±
INO(OFF)
VCOM = ±10V,
VNO = ±10V,
VEN = 0V
±
COM-Off Leakage Current
(Note 4)
VCOM = ±10V,
VNO = ±10V,
VEN = 0V
ICOM(OFF)
VCOM = ±10V,
VNO = ±10V,
VEN = 0V
±
MAX354/MAX355
Fault-Protected Analog Multiplexers
TA = TMIN
to TMAX
285
450
M
500
TA = +25°C
7
TA = TMIN to TMAX
TA = +25°C
TA = TMIN
to TMAX
-5.0
5.0
-50
50
-0.5
COM-On Leakage Current
(Note 4)
2
ICOM(ON)
VCOM = ±10V,
VNO = ±10V,
sequence each
switch on
-25
25
M
-100
100
-0.5
0.02
0.5
C, E
-15
15
M
-50
50
-0.5
0.02
-30
30
M
-200
200
0.02
0.5
C, E
-15
15
M
-100
100
_______________________________________________________________________________________
nA
nA
0.5
C, E
-0.5
Ω
0.5
C, E
TA = +25°C
MAX355 TA = TMIN
to TMAX
0.02
Ω
0.5
M
TA = +25°C
MAX354 TA = TMIN
to TMAX
0.01
C, E
TA = +25°C
MAX355 TA = TMIN
to TMAX
12
15
-0.5
TA = +25°C
MAX354 TA = TMIN
to TMAX
350
C, E
nA
Fault-Protected Analog Multiplexers
(V+ = +15V, V- = -15V, GND = 0V, VAH = VENH = 2.4V, VAL = VENL = 0.8V, TA = TMIN to TMAX, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
TA = +25°C
-5
0.01
TA = TMIN to TMAX
-2
MAX
UNITS
5
nA
2
µA
FAULT
Output Leakage Current
(with Overvoltage)
VD = 0V,
analog overvoltage = ±33V
Input Leakage Current
(with Overvoltage)
VIN = ±25V, VO = ±10V
Input Leakage Current
(with Power Supplies Off)
VIN = ±25V, VEN = VO = 0V,
VA0 = VA1 = VA2 = 0V or 5V
TA = +25°C
TA = TMIN to TMAX
TA = +25°C
-0.1
0.001
-2
-0.1
TA = TMIN to TMAX
-2
2.4
0.1
2
0.001
0.1
2
µA
µA
DIGITAL LOGIC INPUT
Logic High Input Voltage
VA_H, VENH
TA = TMIN to TMAX
Logic Low Input Voltage
VA_L, VENL
TA = TMIN to TMAX
Input Current with
Input Voltage High
IA_H, IENH
VA = VEN = 2.4V
Input Current with
Input Voltage Low
IA_L, IENL
VA = VEN = 0.8V
V
0.8
TA = +25°C
-1
1
TA = TMIN to TMAX
-5
5
TA = +25°C
-1
1
TA = TMIN to TMAX
-5
5
V
µA
µA
SUPPLY
Power-Supply Range
Positive Supply Current
I+
VEN = VA = 5V
Negative Supply Current
I-
VEN = VA = 0V
±4.5
±18
TA = +25°C
-300
300
TA = TMIN to TMAX
-500
500
-1
1
-100
100
TA = +25°C
TA = TMIN to TMAX
V
µA
µA
DYNAMIC
TA = +25°C
Transition Time
tTRANS
Figure1
Enable Turn-On Time
tON(EN)
Figure 2
Enable Turn-Off Time
tOFF(EN)
Figure 2
Break-Before-Make Interval
tOPEN
Figure 3
TA = +25°C
Charge Injection
VCTE
CL = 10nF, VS = 0V, RS = 0Ω,
Figure 4
Off Isolation
180
TA = TMIN to TMAX
250
400
TA = +25°C
160
TA = TMIN to TMAX
250
400
TA = +25°C
80
TA = TMIN to TMAX
200
300
ns
ns
100
ns
TA = +25°C
80
pC
VISO
VEN = 0V, RL = 1kΩ, f = 100kHz,
TA = +25°C
Figure 5
100
dB
Crosstalk Between Channels
VCT
VEN = 2.4V, f = 100kHz,
VGEN = 1Vp-p, RL = 1kΩ,
Figure 6
TA = +25°C
92
dB
Logic Input Capacitance
CIN
f = 1MHz, Figure 7
TA = +25°C
2.5
pF
f = 1MHz, VEN = VD = 0V
TA = +25°C
1.6
pF
NO-Off Capacitance
CNO(OFF)
50
ns
pF
_______________________________________________________________________________________
3
MAX354/MAX355
ELECTRICAL CHARACTERISTICS (continued)
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
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DYNAMIC (cont’d)
COM-Off Capacitance
CCOM(OFF)
f = 1MHz, Figure 7, MAX354
TA = +25°C
VEN = VD = 0V
MAX355
11
COM-On Capacitance
CCOM(ON)
f = 1MHz, Figure 7, MAX354
TA = +25°C
VEN = VD = 0V
MAX355
28
Setting Time (Note 5)
tSETT
0.1%
pF
14
1
TA = +25°C
0.01%
pF
5
µs
2.5
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 +25°C.
Note 5: Guaranteed by design.
__________________________________________Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
600
RON (Ω)
RON (Ω)
0.1
+125°C
+85°C
+70°C
+25°C
500
V+ = +10V
V- = -10V
1200
A:
B:
C:
D:
V+ = +15V
V- = -15V
1400
1
1000
A
400
B
300
C
800
0.01
600
V+ = +15V
V- = -15V
200
200
0
0.0001
-15
-10
-5
0
5
10
-15
15
-10
10
100
-10
15
-5
INO(OFF)
V+ = +15V
V- = -15V
VCOM_ = ±10V
0
5
10
VCOM (V)
CHARGE INJECTION vs. VCOM
200
V+ = +15V
V- = -15V
150
100
Qj (pC)
1
ON LEAKAGE (nA)
10
ICOM(OFF)
0.1
5
100
MAX354-3
V+ = +15V
V- = -15V
VNO_ = ±10V
VCOM_ = 10V
0
ON LEAKAGE vs. TEMPERATURE
OFF LEAKAGE vs. TEMPERATURE
100
-5
ANALOG VOLTAGE (V)
ANALOG VOLTAGE (V)
10
D
400
MAX354-5
0.001
V+ = +15V
V- = -15V
MAX354-4
RON (MΩ)
V+ = +5V
V- = -5V
1600
700
MAX354/5-2
1800
MAX354/5-1b
V+ = +5V
V- = -5V
10
2000
MAX354/5-1a
100
ON-RESISTANCE vs.
VCOM AND TEMPERATURE
ON-RESISTANCE vs. ANALOG VOLTAGE
ON-RESISTANCE vs. ANALOG VOLTAGE
OFF LEAKAGE (nA)
MAX354/MAX355
Fault-Protected Analog Multiplexers
1
50
0
-50
-100
0.1
-150
-75 -50
-25
0
25
50
75 100 125
TEMPERATURE (°C)
4
-200
0.01
0.01
-75 -50
-25
0
25
50
75 100 125
TEMPERATURE (°C)
-10
-5
0
VCOM (V)
_______________________________________________________________________________________
5
10
Fault-Protected Analog Multiplexers
FAULT CURRENT vs. FAULT VOLTAGE
SUPPLY CURRENT vs. TEMPERATURE
I+ (VA_ = 5V)
1m
FAULT CURRENT (A)
I+, I- (µA)
100
V+ = +15V
V- = -15V
VEN = +5V
10m
MAX354-6
1000
I+ (VA_ = 0V)
10
1
V+ = V- = 0V
100µ
10µ
1µ
V+ = +15V
V- = -15V
100m
10n
1n
100p
I0.1
-75 -50
-25
0
25
50
75 100 125
10p
-70
-50
-30
-10
10
30
50
70
FAULT VOLTAGE (V)
TEMPERATURE (°C)
______________________________________________________________Pin Description
PIN
NAME
FUNCTION
MAX354
MAX355
1, 15, 16
—
A0, A2, A1
Address Logic Inputs
—
1, 16
A0, A1
Address Logic Inputs
2
2
EN
Enable Logic Input. See truth tables.
3
3
V-
Negative Supply Voltage Input. Connect to GND for single-supply operation.
4–7
—
NO1–NO4
—
4–7
NO1A–NO4A
8
—
COM
Analog Output—bidirectional
—
8, 9
COMA, COMB
Analog Outputs—bidirectional
9–12
—
NO8–NO5
—
10–13
NO4B–NO1B
13
14
V+
14
15
GND
Analog Inputs—bidirectional
Analog Inputs—bidirectional “A” switch
Analog Inputs—bidirectional
Analog Inputs—bidirectional “B” switch
Positive Supply Voltage Input
Ground
Note: Analog inputs and outputs are electrically identical and completely interchangeable.
_______________________________________________________________________________________
5
MAX354/MAX355
____________________________Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
MAX354/MAX355
Fault-Protected Analog Multiplexers
______________________________________________Test Circuits/Timing Diagrams
+15V
V+
NO1
A2
A1
+10V
NO2-NO7
A0
MAX354
VEN
NO8
EN
-10V
COM
GND
VOUT
V-
35pF
50Ω
LOGIC
INPUT
VEN
300Ω
-15V
50%
0V
VNO1
+15V
SWITCH
OUTPUT
VOUT
V+
NO1B
A1
+10V
90%
0V
90%
A0
VNO8
NO1A-NO4A
VEN
tR < 20ns
tF < 20ns
+3V
NO4B
MAX355
EN
-10V
GND
ON
VOUT
50Ω
tTRANS
tTRANS
COMB
V35pF
300Ω
-15V
Figure 1. Transition Time
+15V
VEN
V+
EN
NO1
+10V
NO2–NO8
A0
A1
MAX354
A2
COM
GND
50Ω
VOUT
V-
35pF
1k
LOGIC
INPUT
VEN
-15V
V+
EN
A1
50Ω
0V
tON(EN)
tOFF(EN)
NO1B
10%
SWITCH
OUTPUT
VOUT
+10V
NO1A–NO4A
NO2B–NO4B,
COMA
A0
50%
0V
+15V
VEN
tR < 20ns
tF < 20ns
+3V
90%
MAX355
GND
COMB
V-
VOUT
1k
35pF
-15V
Figure 2. Enable Switching Time
6
_______________________________________________________________________________________
Fault-Protected Analog Multiplexers
+15V
VEN
+2.4V
V+
EN
NO1–NO8
A0
+10V
50%
0V
MAX354
+5V
A1
VA
tR < 20ns
tF < 20ns
+3V
LOGIC
INPUT
VA
80%
A2
COM
GND
SWITCH
OUTPUT
VOUT
VOUT
V-
35pF
tOPEN
0V
300Ω
50Ω
-15V
Figure 3. Break-Before-Make Interval
+15V
RS
V+
NO
VEN
VS
CHANNEL
SELECT
LOGIC
INPUT
VEN
EN
A0
MAX354
COM
A1
+3V
OFF
ON
OFF
0V
VOUT
A2
CL = 1000nF
GND
V-
∆VOUT
VOUT
∆VOUT IS THE MEASURED VOLTAGE DUE TO CHARGE TRANSFER
ERROR VCTE WHEN THE CHANNEL TURNS OFF.
-15V
VCTE = ∆VOUT x CL
Figure 4. Charge Injection
_______________________________________________________________________________________
7
MAX354/MAX355
_________________________________Test Circuits/Timing Diagrams (continued)
MAX354/MAX355
Fault-Protected Analog Multiplexers
_________________________________Test Circuits/Timing Diagrams (continued)
+15V
NO1
VIN
RS = 50Ω
+15V
10nF
NO1
V+
NO8
R = 1kΩ
VIN
COM
A0
A1
A2
GND EN
V-
VOUT
V+
NO2
NO8
MAX354
MAX354
A0
RG = 50Ω
RL
1k
10nF
COM
A1
A2
GND EN
V-
VOUT
RL
1k
10nF
10nF
-15V
-15V
OFF ISOLATION = 20log
VOUT
CROSSTALK = 20log
VIN
Figure 5. Off Isolation
VOUT
VIN
Figure 6. Crosstalk
+15V
V+
A2
CHANNEL
SELECT
A1
NO1
NO8
MAX354
A0
GND
EN
V-
1MHz
CAPACITANCE
ANALYZER
COM
f = 1MHz
-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
8
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.
_______________________________________________________________________________________
Fault-Protected Analog Multiplexers
Q1
-25V
OVERVOLTAGE S
-25V Q2
D
N-CHANNEL MOSFET
IS TURNED ON
BECAUSE VGS = +25V
S
S
D
G
G
P-CHANNEL
MOSFET IS OFF
Figure 8. -25V Overvoltage with Multiplexer Power Off
-15V
-25V
OVERVOLTAGE
N-CHANNEL MOSFET
IS TURNED ON
BECAUSE VGS = +10V
Q1
-15V FROM
DRIVERS
+15V
Q2
+15V FROM
DRIVERS
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.
Table 1. MAX354 Charge Injection
Supply Voltage
Analog Input Level
Injected Charge
±5V
+2V
0V
-2V
52pC
35pC
16pC
±10V
+5V
0V
-5V
105pC
65pC
25pC
±15V
+10V
0V
-10V
180pC
80pC
15pC
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.
Q3
D
G
Switching Characteristics
and Charge Injection
Q2
D
N-CHANNEL MOSFET
IS TURNED OFF
BECAUSE VGS = -25V
S
G
S
D
G
-15V
+25V FORCED
ON COMMON
OUTPUT LINE BY
EXTERNAL CIRCUITRY
N-CHANNEL
MOSFET IS OFF
Q3
D
G
Figure 9. +25V Overvoltage with Multiplexer Power Off
-15V
Q3
Q1
+25V
OVERVOLTAGE S
+25V
OVERVOLTAGE
N-CHANNEL MOSFET
IS TURNED OFF
BECAUSE VGS = -10V
Q1
+15V
13.5V Q2
-15V
Q3
13.5V
OUTPUT
VTN = 1.5V
+15V FROM
DRIVERS
-15V FROM
DRIVERS
N-CHANNEL
MOSFET IS ON
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
MAX354/MAX355
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 +25°C. For positive overvoltages, that
fault current will initially be 10µA or 20µA, 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.
MAX354/MAX355
Fault-Protected Analog Multiplexers
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.
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.
10
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 1µA.
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 10kΩ 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.
______________________________________________________________________________________
Fault-Protected Analog Multiplexers
Frequency
100kHz
1MHz
One Channel Driven
100dB
80dB
Table 2b. Typical Crosstalk Rejection Ratio
Test Conditions: V IN = 20Vp-p at the tabulated frequency,
RL = 1.5kΩ between OUT and ground, EN = 0V.
20Vp-p
VISO = 20log —————
VOUT (p-p)
Frequency
100kHz
1MHz
RL = 1.5kΩ
92dB
72dB
RL = 10kΩ
76dB
56dB
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
V+
V-
GND
MAX354
NO1
A2
A1
A0
EN
ON SWITCH
NO2
NO3
X
X
X
0
NONE
NO4
0
0
0
1
1
0
0
1
1
2
0
1
0
1
3
0
1
1
1
4
1
0
0
1
5
1
0
1
1
6
1
1
0
1
7
1
1
1
1
8
COM
NO5
NO6
NO7
NO8
DECODERS / DRIVERS
A0
MAX355
A1
V+
A2
V-
EN
LOGIC "O" VAL ≤ +0.8V, LOGIC "1" VAH ≥ +2.4V
GND
NO1A
NO2A
NO3A
MAX355
COMA
NO4A
NO1B
COMB
NO2B
NO3B
NO4B
A1
A0
EN
ON SWITCH
X
X
0
NONE
0
0
1
1
0
1
1
2
1
0
1
3
1
1
1
4
DECODERS / DRIVERS
LOGIC "O" VAL ≤ +0.8V, LOGIC "1" VAH ≥ +2.4V
A0
A1
EN
______________________________________________________________________________________
11
MAX354/MAX355
Table 2a. Typical Off-Isolation Rejection
Ratio
MAX354/MAX355
Fault-Protected Analog Multiplexers
__________________________________________________________Chip Topographies
MAX354
EN
A0
A1
A2
MAX355
EN
GND
A0
A1
GND
V-
V-
V+
N.C.
V+
N01
N01A
N05
N01B
0.130"
(3.30mm)
0.130"
(3.30mm)
N02
N06
N03
N.C.
N04
COM N08
N02A
N02B
N03A
N03B
N04A
N07
COMA COMB
N04B
0.115"
(2.92mm)
0.115"
(2.92mm)
TRANSISTOR COUNT: 256
SUBSTRATE CONNECTED TO V+
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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
© 1996 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.