Precision, Low-Voltage Analog Switches

8

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__________Applications Information

Operation with Supply Voltages

Other than ±5V

The MAX381/MAX383/MAX385 switches operate with

±3.0V to ±8V bipolar supplies and a +3V to +15V single

supply. In either case, analog signals ranging from V+ to

V- can be switched. The

Typical Operating Characteristics

graphs show the typical on-resistance variation with ana-

log signal and supply voltage. The usual on-resistance

temperature coefficient is 0.5%/°C (typ).

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 3V

supply.

______________________________________________________________Pin Description

COM

V-

V+

NO

* INTERNAL PROTECTION DIODES

D2

D1

-5V

+5V

MAX381

MAX383

MAX385

*

*

*

*

Figure 1. Overvoltage Protection Using Two External Blocking

Diodes

1, 8

COM_

Analog Switch Common Terminal

2–7, 12

N.C.

Not Internally Connected

9, 16

NO_

Analog Switch Normally Open Terminal

—

NC_

Analog Switch Normally Closed Terminal

10, 15

IN_*

Logic Level Input (Normally Low)

11

V+

Analog Signal and Logic Positive Supply Input

14

V-

Analog Signal Negative Supply Input

NAME

FUNCTION

MAX381

1, 3, 6, 8

2, 7, 12

9, 16

4, 5

10, 15

11

14

MAX383

1, 3, 6, 8

2, 7, 12

4, 5, 9, 16

—

10, 15

11

14

MAX385

PIN

13

GND

Logic Negative Supply Input (Ground)

13

13

* IN1 controls COM1 and COM3; IN2 controls COM2 and COM4.