Fault-Protected, High-Voltage,

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

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11

Transient Fault Condition

When a fast rising or falling transient on NO_ exceeds

V+ or V-, the output (COM_) follows the input (NO_) to

the supply rail with only a few nanoseconds delay. This

delay is due to the switch on-resistance and circuit

capacitance to ground. When the input transient

returns to within the supply rails, however, there is a

longer output recovery time. For positive faults, the

recovery time is typically 2.5µs. For negative faults, the

recovery time is typically 1.3µs. These values depend

on the COM_ output resistance and capacitance. The

delays do not depend on the fault amplitude. Higher

COM_ output resistance and capacitance increase the

recovery times.

Non-Fault-Protected Pins

FETs N2 and P2 can source about ±10mA from V+ or

V- to the COM_ pin in the fault condition (Figure 1).

Ensure that if the COM_ pin is connected to a low -

impedance load, the 30mA absolute maximum current

rating is never exceeded, both in normal and fault con-

ditions.

The GND, COM_, EN, and A_ pins do not have fault

protection. Reverse ESD protection diodes are internal-

ly connected between GND, COM_, A_, EN, and both

V+ and V-. If a signal on GND, COM_, EN, or A_

exceeds V+ or V- by more than 300mV, one of these

diodes will conduct. During normal operation, these

reverse-biased ESD diodes leak a few nanoamps of

current to V+ and V-.

Fault Protection Voltage and Power-Off

The maximum fault voltage on the NO_ pins is ±40V

from ground when the power is off. With ±15V supply

voltages, the highest voltage on NO_ can be V- + 40V,

and the lowest voltage on NO_ can be V+ - 40V.

Caution: Exceeding these limits can damage the IC.

Logic-Level Thresholds

The logic-level thresholds are CMOS and TTL compati-

ble with V+ = 4.5V to 16.5V.

Applications Information

Ground

There is no connection between the analog signal

paths and GND. The analog signal paths consist of an

N-channel and a P-channel MOSFET with their sources

and drains paralleled, and their gates driven out of

phase to V+ and V- by the logic-level translators.

V+ and GND power the internal logic and logic-level

translators and set the input logic thresholds. The logic-

level translators convert the logic levels to switched V+

and V- signals to drive the gates of the channel

MOSFETs. This drive signal is the only connection

between the power supplies and the analog signals.

GND, A_, EN, and COM_ have ESD protection diodes

to V+ and V-.

Supply Current Reduction

When the logic signals are driven rail-to-rail from 0 to

+15V or -15V to +15V, the current consumption will be

reduced from 300µA (typ) to 180µA.

Power Supplies

The MAX4534/MAX4535 operate with bipolar supplies

between ±4.5V and ±20V. The V+ and V- supplies

need not be symmetrical, but their sum cannot exceed

the 44V absolute maximum rating.

The MAX4534/MAX4535 operate from single supplies

between +9V and +36V when V- is connected to GND.