Fault-Protected, High-Voltage,

Single 4-to-1/Dual 2-to-1 Multiplexers

Detailed Description

The MAX4534/MAX4535 differ considerably from tradi-

tional fault-protected multiplexers, offering several

advantages. First, they are constructed with two paral-

lel FETs, allowing very low resistance when the switch

is on. Second, they allow signals on the NO_ pins that

are within or beyond the supply rails to be passed

through the switch to the COM terminal. This allows rail-

to-rail signal operation. Third, when a signal on VNO_

exceeds the supply rails (i.e., a fault condition), the

voltage on COM_ is limited to the supply rails.

Operation is identical for both fault polarities.

When the NO_ voltage goes beyond supply rails (fault

condition), the NO_ input becomes high impedance

regardless of the switch state or load resistance. When

power is removed, and the fault protection is still in

effect, the NO_ terminals are a virtual open circuit. The

fault can be up to ±40V, with V+ = V- = 0. If the switch

is on, the COM_ output current is furnished from the V+

or V- pin by “booster” FETs connected to each supply

pin. These FETs can source or sink up to 10mA.

The COM_ pins are not fault-protected. If a voltage

source is connected to any COM_ pin, it should be lim-

ited to the supply voltages. Exceeding the supply volt-

age will cause high currents to flow through the ESD

protection diodes, damaging the device (see Absolute

Maximum Ratings).

Figure 1 shows the internal construction, with the ana-

log signal paths shown in bold. A single, normally open

(NO) switch is shown. The analog switch is formed by

the parallel combination of N-channel FET N1 and P-

channel FET P1, which are driven on and off simultane-

ously, according to the input fault condition and the

logic level state.

.

Pin Descriptions

Truth Tables

NAME

FUNCTION

1

A0

Address Bit 0

2

EN

Enable Input

PIN

3

V-

Negative Supply Voltage

4

NO1

Channel Input 1 (fault protected)

10

NO4

Channel Input 4 (fault protected)

7

COM

Analog Output

6, 8, 9

N.C.

No connection

5

NO2

Channel Input 2 (fault protected)

14

A1

Address Bit 1

13

GND

Ground

12

V+

Positive Supply Voltage

11

NO3

Channel Input 3 (fault protected)

MAX4534 (Single 4-to-1 Mux)

MAX4535 (Dual 2-to-1 Mux)

NAME

FUNCTION

1

A0

Address Bit 0

2

EN

Enable Input

PIN

3

V-

Negative Supply Voltage

4

NO1A

Channel Input 1A (fault protected)

8

COMB

Mux Output B

7

COMA

Mux Output A

6, 9, 14

N.C.

No connection

5

NO2A

Channel Input 2A (fault protected)

13

GND

Ground

12

V+

Positive Supply Voltage

11

NO1B

Channel Input 1B (fault protected)

10

NO2B

Channel Input 2B (fault protected)

X

X

0

0

0

1

1

0

1

1

0

1

1

1

1

None

NO1

NO2

NO3

NO4

A0

A1

EN

ON SWITCH

MAX4534 (Single 4-to-1 Mux)

MAX4535 (Dual 2-to-1 Mux)

_______________________________________________________________________________________

9

COMA

EN

COMB

A0

NO2A

NO1A

None

1

1

0

NO2B

1

NO1B

0

None

X