Applications Information

Analog Signal Levels

Analog signals can range over the supply voltage (V+

to GND) with on-resistance changing very little over the

entire range (see Typical Operating Characteristics).

The MAX4599 is bidirectional, so the NO, NC, and

COM pins can be used either as inputs or outputs.

Power-Supply Sequencing and

Overvoltage Protection

Proper power-supply sequencing is recommended for

all CMOS devices. Always apply V+ before applying

analog signals or logic inputs, especially if the analog

or logic signals are not current limited. If this sequenc-

ing is not possible, and if the analog or logic inputs are

not current limited to < 20mA, add a small-signal diode

(D1) as shown in Figure 1. If the analog signal can dip

below GND, add D2. Adding protection diodes

reduces the analog signal range to a diode drop (about

0.7V) below V+ for D1 or to a diode drop above ground

for D2. The addition of diodes does not affect leakage.

On-resistance increases by a small amount at low sup-

ply voltages. Maximum supply voltage (V+) must not

exceed 6V.

Protection diodes D1 and D2 also protect against some

overvoltage situations. A fault voltage up to the

absolute maximum rating at an analog signal input

does not damage the device, even if the supply voltage

is below the signal voltage.

Low-Voltage, Single-Supply,

SPDT Analog Switch in SC70

6

_______________________________________________________________________________________

-95

0.01

0.1

1

10

100 200

FREQUENCY RESPONSE

-75

FREQUENCY (MHz)

-55

-35

-15

-25

-45

-65

-85

-5

ON-RESPONSE

OFF-ISOLATION

Typical Operating Characteristics (continued)

1

0.01

0.01

0.1

100

110

TOTAL HARMONIC DISTORTION PLUS

NOISE vs. FREQUENCY

0.1

FREQUENCY (kHz)

Ω

NAME

FUNCTION

1

IN

Digital Control Input

2

V+

Positive Supply Voltage

PIN

3

GND

Ground

4

NC

Analog Switch Normally Closed

6

NO

Analog Switch Normally Open

5

COM

Analog Switch Common

Pin Description

POSITIVE SUPPLY

COM

NO

OR

NC

D2

D1

GND

Vg

V+

Figure 1. Overvoltage Protection Using Two External Blocking

Diodes