Applications Information

Operation with

Supply Voltages Other than 15V

Using supply voltages less than ±15V reduces the ana-

log signal range. The DG408/DG409 switches operate

with ±5V to ±20V bipolar supplies or with a +5V to

+40V single supply. Connect V- to GND when operat-

ing with a single supply. Both device types can also

operate with unbalanced supplies, such as +24V and

-5V. The

Typical Operating Characteristics graphs

show typical on-resistance with 20V, 15V, 10V, 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 may cause permanent damage to the devices.

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

logic inputs, S or D. If power-supply sequencing is not

possible, add two small signal diodes in series with

supply pins for overvoltage protection (Figure 1).

Adding diodes reduces the analog signal range to 1V

below V+ and 1V above V-, but does not affect the

devices’ low switch resistance and low leakage charac-

teristics. Device operation is unchanged, and the differ-

ence between V+ and V- should not exceed +44V.

Improved, 8-Channel/Dual 4-Channel,

CMOS Analog Multiplexers

6

_______________________________________________________________________________________

______________________________________________________________Pin Description

S

D

V-

V+

DG408

DG409

Figure 1. Overvoltage Protection Using External Blocking

Diodes

PIN

DG408

DG409

NAME

FUNCTION

1, 15, 16

A0, A2, A1

Address Inputs

—

—

A0, A1

Address Inputs

2

2

EN

Enable Input

3

3

V-

Negative Supply Voltage Input

4–7

—

S1–S4

Bidirectional Analog Inputs

—

4–7

S1A–S4A

Bidirectional Analog Inputs

8

—

D

Bidirectional Analog Output

—

8, 9

DA, DB

Bidirectional Analog Outputs

9–12

—

S8–S5

Bidirectional Analog Inputs

—

10–13

S4B–S1B

Bidirectional Analog Inputs

13

14

V+

Positive Supply Voltage Input

14

15

GND

Ground

1, 16