Applications Information

Operation with Supply Voltages

Other than ±5V

Using supply voltages less than ±5V reduces the analog

signal range. The MAX398/MAX399 muxes operate with

±3V to ±8V bipolar supplies or with a +3V to +15V single

supply. Connect V- to GND when operating with a single

supply. Both device types can also operate with unbal-

anced supplies, such as +10V and -5V. The Typical

Operating Characteristics graphs show typical on-resis-

tance with ±3V, ±5V, +3V, and +5V supplies. (Switching

times increase by a factor of two or more for operation at

+5V.)

Overvoltage Protection

Proper power-supply sequencing is recommended for

all CMOS devices. Do not exceed the absolute maxi-

mum ratings, because stresses beyond the listed rat-

ings can cause permanent damage to the devices.

Always sequence V+ on first, then V-, followed by the

logic inputs, NO, or COM. If power-supply sequencing

is not possible, add two small signal diodes (D1, D2) in

series with supply pins for overvoltage protection

(Figure 1). Adding diodes reduces the analog signal

range to one diode drop below V+ and one diode drop

above V-, but does not affect the devices’ low switch

resistance and low leakage characteristics. Device

operation is unchanged, and the difference between

V+ and V- should not exceed 17V. These protection

diodes are not recommended when using a single supply.

Precision, 8-Channel/Dual 4-Channel,

Low-Voltage, CMOS Analog Multiplexers

8

_______________________________________________________________________________________

Test Circuits/Timing Diagrams

COM

V-

V+

NO

* INTERNAL PROTECTION DIODES

D2

D1

-5V

+5V

MAX398

MAX399

*

*

*

*

Figure 1. Overvoltage Protection Using External Blocking Diodes

50%

tR < 20ns

tF < 20ns

+3V

0

0

LOGIC

INPUT

SWITCH

OUTPUT

+5V

VOUT

-5V

GND

V+

A1

V-

A2

A0

EN

NO1

NO2–NO7

NO8

COM

+5V

-5V

50

Ω

MAX398

300

Ω

35pF

+5V

VOUT

-5V

GND

V+

A0

V-

A1

EN

NO1B

NO1A–NO4A

NO4B

COMB

+5V

50

Ω

MAX399

300

Ω

35pF

90%

90%

ON

-5V

Figure 2. Transition Time