Switches with Negative Rail Capability

8

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Detailed Description

The MAX4901–MAX4905 are low on-resistance, low-volt-

age, dual-SPST and single-SPDT analog switches that

operate from a +1.8V to +5.5V supply and are fully speci-

fied for nominal 3.0V applications. The devices feature a

negative signal capability that allows signals below

ground to pass through without distortion and

have break-before-make switching (MAX4903/

MAX4904/MAX4905).

The MAX4905 features a comparator that can be used for

headphone or mute detection. The comparator threshold

The MAX4902/MAX4904/MAX4905 feature an internal

shunt resistor to discharge any capacitance at NO_ and

NC connection points. This reduces the click-and-pop

sounds that occur when switching audio signals.

Applications Information

Digital Control Inputs

The MAX4901–MAX4905 logic inputs accept up to

+5.5V, regardless of supply voltage. For example, with

a +3.3V supply, IN_ can be driven low to GND and

high to +5.5V, allowing for mixing of logic levels in a

system. Driving IN_ rail-to-rail minimizes power

consumption. For a +1.8V supply voltage, the logic

thresholds are 0.5V (low) and 1.4V (high). For a +5V

supply voltage, the logic thresholds are 0.8V (low) and

2.0V (high).

Analog Signal Levels

The on-resistance of the MAX4901–MAX4905 changes

very little for analog input signals across the entire sup-

ply-voltage range (see the Typical Operating

Characteristics). The switches are bidirectional.

5.5V, including signals below ground with minimal dis-

tortion. Note that there are shunt resistors on NO_ and

NC when they are unconnected to COM_ for the

MAX4902/MAX4904/MAX4905.

Comparator (MAX4905)

The MAX4905 includes a comparator that can be used

for mute and headphone detection functions. The posi-

When the negative terminal (CMP-) is below the thresh-

old, the comparator output (CMPO) is a logic high.

of headphones because headphone audio signals are

Shunt Resistor

(MAX4902/MAX4904/MAX4905)

The 50

Ω shunt resistors on the MAX4902/MAX4904/

MAX4905 automatically discharge any capacitance at

the NC or NO_ terminals when they are unconnected to

COM_. This reduces audio click-and-pop sounds that

occur when switching between audio sources.

MAX4905

COM

IN

CMP-

GND

MUTE

BUTTON

SPEAKER

AUDIO

SOURCE

1

NC

NO

CMPO

3

AUDIO

SOURCE

2

DirectDrive

SOURCE

Typical Operating Circuit