MAXIM MAX354, MAX355 Technical data

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 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.

________________________Applications

Data-Acquisition Systems Industrial and Process Control Avionics ATE Equipment Signal Routing Redundant/Backup Systems

____________________________Features

♦ 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

______________Ordering Information

PART

MAX354CPE

MAX354CWE MAX354C/D 0°C to +70°C MAX354EPE MAX354EWE -40°C to +85°C MAX354MJE -55°C to +125°C 16 CERDIP** MAX355CPE MAX355CWE MAX355C/D 0°C to +70°C MAX355EPE MAX355EWE -40°C to +85°C MAX355MJE -55°C to +125°C 16 CERDIP**

* Dice are tested at TA = +25°C only. ** Contact factory for availability.

TEMP. RANGE PIN-PACKAGE

0°C to +70°C 0°C to +70°C

-40°C to +85°C 16 Plastic DIP

0°C to +70°C 16 Plastic DIP 0°C to +70°C

-40°C to +85°C 16 Plastic DIP

16 Plastic DIP 16 Wide SO Dice*

16 Wide SO

16 Wide SO Dice*

16 Wide SO

MAX354/MAX355

__________________________________________________________Pin Configurations

TOP VIEW

MAX354

LOGIC

V-

NO1

NO2

NO3

NO4

COM

DIP/SO

________________________________________________________________

A1 A2

GND

V+

13 12

NO5 NO6

NO7

NO8

A0 EN

VNO1A NO2A NO3A NO4A

COMA

MAX355

1 2

LOGIC

3 4 5 6 7 8

DIP/SO

16 15 14 13 12 11 10

Maxim Integrated Products

A1 GND V+ NO1B NO2B NO3B NO4B COMB

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800

Fault-Protected Analog Multiplexers

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

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

MAX354/MAX355

(V+ = +15V, V- = -15V, GND = 0V, VAH= V

= 2.4V, VAL= V

ENH

SWITCH

Analog Signal Range Fault-Free Analog

Signal Range

On-Resistance (Note 2)

On-Resistance Matching Between Channels

NO-Off Leakage Current (Note 4)

COM-Off Leakage Current (Note 4)

COM

∆R

NO(OFF)

COM(OFF)

(Note 1)

, V

V+ = +15V, V- = -15V (Note 1)

INO= 1.0mA, V

(Note 3) V

COM

= ±10V, VNO= ±10V, VEN= 0V

V V

COM NO

= ±10V,

VEN= 0V

= ±10V,

COM NO

= ±10V,

COM

VEN= 0V

= ±10V,

COM

COM-On Leakage Current (Note 4)

COM(ON)

= ±10V,

sequence each switch on

Peak Current into Any Terminal........................................±50mA

Continuous Power Dissipation (T

= +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

= 0.8V, TA= T

ENL

MIN

to T

, unless otherwise noted.)

MAX

CONDITIONS

-12 12 285 350

450 500

712

= ±10V

MAX354

MAX355

MAX354

MAX355

TA= +25°C TA= T

MIN

to T

MAX

TA= +25°C TA= T

MIN

TA= +25°C TA= T

MIN

to T

MAX

TA= +25°C TA= T

MIN

to T

MAX

TA= +25°C TA= T

MIN

to T

MAX

TA= +25°C TA= T

MIN

to T

MAX

TA= +25°C TA= T

MIN

to T

MAX

to T

C, E M

MAX

C, E M

-0.5 0.01 0.5

-5.0 5.0

-50 50

-0.5 0.02 0.5

-25 25

-100 100

-0.5 0.02 0.5

-15 15

-50 50

-0.5 0.02 0.5

-30 30

-200 200

-0.5 0.02 0.5

-15 15

-100 100

UNITSMIN TYP MAXSYMBOLPARAMETER

V(V+ - 40) (V- + 40) V

Ω

2 _______________________________________________________________________________________

Fault-Protected Analog Multiplexers

ELECTRICAL CHARACTERISTICS (continued)

(V+ = +15V, V- = -15V, GND = 0V, VAH= V

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

A_H

A_L

A_H

A_L

, V , V

, I

ENH ENL

ENH

ENL

SUPPLY

I+Positive Supply Current

I-Negative Supply Current

DYNAMIC

Transition Time

Enable Turn-On Time

Enable Turn-Off Time Break-Before-Make Interval Charge Injection

Off Isolation

TRANS

ON(EN)

OFF(EN)

OPEN

CTE

ISO

= 2.4V, VAL= V

ENH

= 0.8V, TA= T

ENL

CONDITIONS

VD= 0V, analog overvoltage = ±33V

VIN= ±25V, VO= ±10V

VIN= ±25V, VEN= VO= 0V, VA0= VA1= VA2= 0V or 5V

VA= VEN= 2.4V µA

VEN= VA= 5V

VEN= VA= 0V

Figure1

Figure 2

Figure 2 Figure 3

CL= 10nF, VS= 0V, RS= 0Ω, Figure 4

VEN= 0V, RL= 1kΩ, f = 100kHz, Figure 5

MIN

TA= +25°C TA= T

MIN

TA= +25°C TA= T

MIN

TA= +25°C TA= T

MIN

TA= T

MIN MIN

TA= +25°C TA= T

MIN

TA= +25°C TA= T

MIN

TA= +25°C TA= T

MIN

TA= +25°C TA= T

MIN

TA= +25°C TA= T

MIN

TA= +25°C TA= T

MIN

TA= +25°C TA= T

MIN

TA= +25°C TA= +25°C

TA= +25°C

to T

, unless otherwise noted.)

MAX

to T

MAX

-0.1 0.001 0.1

to T

MAX

-2 2

-0.1 0.001 0.1

to T

to T to T

MAX

MAX MAX

-2 2

-1 1

to T

MAX

-5 5

-1 1

to T

MAX

-5 5

-300 300

to T

MAX

-500 500

-1 1

to T

MAX

-100 100

0.8V

180 250

400

160 250

400

80 200

300

MAX354/MAX355

UNITSMIN TYP MAXSYMBOLPARAMETER

nA-5 0.01 5 µA-2 2

µA

V2.4V VTA= T

µAVA= VEN= 0.8V

V±4.5 ±18Power-Supply Range

µA

ns ns50 100t

pC80V

dB100V

VEN= 2.4V, f = 100kHz,

Crosstalk Between Channels dB92

GEN

= 1V

, RL= 1kΩ,

p-p

TA= +25°C

Figure 6

Logic Input Capacitance f = 1MHz, Figure 7 TA= +25°C NO-Off Capacitance

NO(OFF)

f = 1MHz, VEN= VD= 0V

TA= +25°C

_______________________________________________________________________________________ 3

pF pF2.5C pF1.6C

Fault-Protected Analog Multiplexers

ELECTRICAL CHARACTERISTICS (continued)

(V+ = +15V, V- = -15V, GND = 0V, VAH= V

= 2.4V, VAL= V

ENH

= 0.8V, TA= T

ENL

MIN

to T

, unless otherwise noted.)

MAX

CONDITIONS

DYNAMIC (cont’d)

COM-Off Capacitance pF

COM-On Capacitance pF

Setting Time (Note 5)

COM(OFF)

COM(ON)

SETT

f = 1MHz, Figure 7,

VEN= VD= 0V

f = 1MHz, Figure 7,

VEN= VD= 0V

0.1%

0.01%

MAX354 MAX355 MAX354 MAX355

TA= +25°C

5 28 14

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: ∆R

MAX354/MAX355

= R

ON(MAX)

- R

ON(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.)

ON-RESISTANCE vs. ANALOG VOLTAGE



100

(MΩ)

0.1

0.01

0.001

0.0001

-15 15

V+ = +5V V- = -5V

V+ = +15V V- = -15V

-10 -5 10

ANALOG VOLTAGE (V)



OFF LEAKAGE vs. TEMPERATURE

100

V+ = +15V V- = -15V

= ±10V

NO_

OFF LEAKAGE (nA)

0.1

0.01

= 10V

COM_

-75 75 100 125

-50 -25 50

TEMPERATURE (°C)

COM(OFF)

NO(OFF)

2000 1800

MAX354/5-1a

1600 1400 1200

(Ω)

1000

MAX354-3

ON LEAKAGE (nA)

0.01

ON-RESISTANCE vs. ANALOG VOLTAGE

800

V+ = +15V

600

V- = -15V

400 200

-15 15

-10 -5 10 ANALOG VOLTAGE (V)

ON LEAKAGE vs. TEMPERATURE

100

V+ = +15V V- = -15V

= ±10V

COM_

0.1

-75 75 100 125

-50 -25 50



V+ = +5V V- = -5V

V+ = +10V V- = -10V



TEMPERATURE (°C)

700

MAX354/5-1b

600

500

(Ω)

400

300



200

100

-10 -5 10

200

MAX354-4

150 100

(pC)

-50

-100

-150

-200

-10 5 10

4 _______________________________________________________________________________________

ON-RESISTANCE vs.

AND TEMPERATURE

COM

V+ = +15V V- = -15V

COM

CHARGE INJECTION vs. V

V+ = +15V V- = -15V



-5 V

COM

A: +125°C B: +85°C C: +70°C D: +25°C

(V)



(V)

UNITSMIN TYP MAXSYMBOLPARAMETER

µs

MAX354/5-2

A B

C D

COM

MAX354-5

Fault-Protected Analog Multiplexers

____________________________Typical Operating Characteristics (continued)

(TA = +25°C, unless otherwise noted.)

SUPPLY CURRENT vs. TEMPERATURE



1000

V+ = +15V V- = -15V

= +5V

100

I+, I- (µA)

0.1

-75 75 100 125

-50 -25 50

TEMPERATURE (°C)

I+ (VA_ = 5V)

I+ (VA_ = 0V)

I-

MAX354-6

FAULT CURRENT vs. FAULT VOLTAGE

10m

100µ

10µ

1µ

100m

10n

FAULT CURRENT (A)

100p

10p

-50

-70 -10 10 30 50 70

-30



V+ = V- = 0V

V+ = +15V V- = -15V

FAULT VOLTAGE (V)

______________________________________________________________Pin Description

MAX354/MAX355

FUNCTIONNAME

MAX355MAX354

—

1, 16

Address Logic InputsA0, A2, A11, 15, 16 Address Logic InputsA0, A1 Enable Logic Input. See truth tables.EN22 Negative Supply Voltage Input. Connect to GND for single-supply operation.V-33 Analog Inputs—bidirectionalNO1–NO4—4–7 Analog Inputs—bidirectional “A” switchNO1A–NO4A4–7— Analog Output—bidirectionalCOM—8 Analog Outputs—bidirectionalCOMA, COMB8, 9— Analog Inputs—bidirectionalNO8–NO5—9–12 Analog Inputs—bidirectional “B” switchNO4B–NO1B10–13— Positive Supply Voltage InputV+1413 GroundGND1514

Note: Analog inputs and outputs are electrically identical and completely interchangeable.

_______________________________________________________________________________________ 5

Fault-Protected Analog Multiplexers

______________________________________________Test Circuits/Timing Diagrams

+15V

V+

NO2-NO7

-15V

V+

NO1A-NO4A

-15V

V-

COMB

V-

NO1

NO8

COM

NO1B

NO4B

300Ω

+10V

-10V

+10V

-10V

35pF

LOGIC

OUT

INPUT V

SWITCH OUTPUT V

OUT

+3V

NO1

NO8

TRANS

50%

90%

tR < 20ns

< 20ns

90%

TRANS

A1 A0

MAX354

50Ω

MAX354/MAX355

50Ω

GND

+15V

A1 A0

MAX355

GND

Figure 1. Transition Time

+15V

GND

V+

MAX354

+15V

V+

NO1A–NO4A

NO2B–NO4B,

MAX355

NO1

NO2–NO8

COM

V-

-15V

NO1B

COMA

COMB

V-

-15V

+10V

OUT

+10V

35pF

OUT

LOGIC INPUT V

SWITCH OUTPUT V

OUT

+3V

ON(EN)

50%

90%

50Ω



50Ω

Figure 2. Enable Switching Time

6 _______________________________________________________________________________________

tR < 20ns

< 20ns

10%

OFF(EN)

Fault-Protected Analog Multiplexers

_________________________________Test Circuits/Timing Diagrams (continued)

+15V

GND

V+

MAX354

NO EN

A0 A1 A2

GND

NO1–NO8

COM

V-

-15V

+15V

V+

MAX354

300Ω

V-

-15V

COM

+10V

OUT

35pF

OUT

CL = 1000nF

LOGIC INPUT V

OUT

+3V

LOGIC INPUT

+5V

SWITCH OUTPUT V

OUT

IS THE MEASURED VOLTAGE DUE TO CHARGE TRANSFER

∆V

OUT

ERROR V  V

WHEN THE CHANNEL TURNS OFF.

CTE

= ∆V

CTE

OUT x CL

50%

80%

ONOFF OFF

OPEN

tR < 20ns

< 20ns

∆V

OUT

+2.4V

A0 A1

50Ω

Figure 3. Break-Before-Make Interval

CHANNEL

SELECT

MAX354/MAX355

Figure 4. Charge Injection

_______________________________________________________________________________________ 7

Fault-Protected Analog Multiplexers

_________________________________Test Circuits/Timing Diagrams (continued)

10nF

+15V

10nF

+15V

= 50Ω

NO1

NO8

V+

R = 1kΩ

MAX354

A1 A2

GND

MAX354/MAX355

10nF

COM

V-

-15V

OFF ISOLATION = 20log

OUT

L

OUT

= 50Ω

Figure 5. Off Isolation Figure 6. Crosstalk

+15V

GND

V+

MAX354

V-

-15V

NO1

NO8

COM

1MHz

CAPACITANCE

ANALYZER

f = 1MHz

CHANNEL

SELECT

GND

V+

MAX354

10nF

COM

V-

-15V CROSSTALK = 20log

OUT

L



OUT

NO1

NO2

NO8 A0

A1 A2

Figure 7. NO/COM Capacitance

_______________Detailed Description

1.5V below the supply rails and maintains the correct polarity. There are no glitches or polarity reversals

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 _______________________________________________________________________________________

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 V

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

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 VTNis typically 1.5V and VTPis 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.

Table 1. MAX354 Charge Injection

Supply Voltage Analog Input Level Injected Charge

+2V

±5V

-2V

+5V

±10V

-5V

+10V

±15V

-10V

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, V

= VA2= 0V, VOis toggled at

a 2kHz rate between 0V and 3V. +100pC of charge creates a +100mV step when injected into a 1000pF load capacitance.

52pC 35pC 16pC

105pC

65pC 25pC

180pC

80pC 15pC

MAX354/MAX355

-25V

OVERVOLTAGE

N-CHANNEL MOSFET

IS TURNED ON

BECAUSE V

= +25V

P-CHANNEL

MOSFET IS OFF

-25V S

Figure 8. -25V Overvoltage with Multiplexer Power Off

+15V-15V -15V

-25V

OVERVOLTAGE

N-CHANNEL MOSFET

IS TURNED ON

BECAUSE V

= +10V

-15V FROM DRIVERS

P-CHANNEL

MOSFET IS OFF

Q2 Q3

+15V FROM

DRIVERS

+25V FORCED

ON COMMON

OUTPUT LINE BY

EXTERNAL CIRCUITRY

N-CHANNEL

MOSFET IS OFF

Figure 10. -25V Overvoltage on an Off Channel with Multiplexer Power Supply On

_______________________________________________________________________________________ 9

+25V

OVERVOLTAGE

N-CHANNEL MOSFET

IS TURNED OFF

BECAUSE V

= -25V

Figure 9. +25V Overvoltage with Multiplexer Power Off

+15V-15V -15V

+25V

OVERVOLTAGE

N-CHANNEL MOSFET

IS TURNED OFF

BECAUSE V

= -10V

+15V FROM

DRIVERS

13.5V

= 1.5V

-15V FROM DRIVERS

Q2 Q3

13.5V

OUTPUT

N-CHANNEL

MOSFET IS ON

Figure 11. +25V Overvoltage Input to the On Channel

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 RONplus 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

MAX354/MAX355

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

Operating Characteristics

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 RON, 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.

show RONfor +15V and ±5V

Other than ±15V

Typical

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 RONplus 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.

10 ______________________________________________________________________________________

Fault-Protected Analog Multiplexers

Table 2a. Typical Off-Isolation Rejection Ratio

Frequency 100kHz 1MHz

One Channel Driven 100dB 80dB

Test Conditions: V

= 1.5kΩ between OUT and ground, EN = 0V.

= 20Vp-p at the tabulated frequency,

= 20log —————

ISO

20Vp-p

OUT

(p-p)

Table 2b. Typical Crosstalk Rejection Ratio

Frequency 100kHz 1MHz

RL= 1.5kΩ 92dB 72dB

RL= 10kΩ 76dB 56dB

Test Conditions: Specified RLconnected from OUT to ground, EN = +5V, A 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.

= A1= A2= +5V (Channel 1 selected). 20Vp-p

__________________________________________Functional Diagrams/Truth Tables

MAX354

NO1 NO2

NO3 NO4

NO5 NO6

NO7 NO8

V+ V- GND

DECODERS / DRIVERS

A0 A1 A2 EN

COM

MAX354

A0A1A2 EN ON SWITCH

X

0

NONE

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

LOGIC "O" VAL ≤ +0.8V, LOGIC "1" VAH ≥ +2.4V

1 2 3 4 5 6 7 8

MAX354/MAX355

MAX355

NO1A NO2A

NO3A NO4A

NO1B NO2B

NO3B NO4B

V+ V- GND

DECODERS / DRIVERS

A0 A1 EN

COMA

COMB

X 0 0 1 1

LOGIC "O" VAL ≤ +0.8V, LOGIC "1" VAH ≥ +2.4V

MAX355

A0A1 EN ON SWITCH

X

0

NONE

0

1

0

1

1 2 3 4

______________________________________________________________________________________ 11

Fault-Protected Analog Multiplexers

__________________________________________________________Chip Topographies

MAX354

V-

N01

MAX354/MAX355

N02

N03

N04 COM N08 N07

A0 A1 A2 GND

0.115"

(2.92mm)

V-

V+

N05

0.130"

(3.30mm)

N06

N.C.

N01A

N02A

N03A

N04A

TRANSISTOR COUNT: 256 SUBSTRATE CONNECTED TO V+

MAX355

A0 A1 GND

V+ N.C.

N01B

0.130"

(3.30mm)

N02B

N03B

COMA COMB N04B

0.115"

(2.92mm)

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.

__________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600

MAXIM MAX354, MAX355 Technical data

Specifications and Main Features

Frequently Asked Questions

User Manual