Low-Voltage, 60

4:1 Analog Multiplexer in QFN

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7

Detailed Description

The MAX4704 low-voltage, 4-channel analog multiplexer

operates from a single +1.8V to +5.5V supply. When

powered from a +2.7V supply, the device has a 60

Ω

and 5

+1.8V-logic compatible from a +2.7V to +3.3V supply.

Applications Information

Digital Control Inputs

The MAX4704 logic inputs are +1.8V CMOS logic com-

patible for 3V operation and TTL compatible for 5V

operation of V+. Driving ADD_ rail-to-rail minimizes

power consumption.

Analog Signal Levels

Analog signals that range over the entire supply volt-

age (V+ to GND) are passed with very little change in

on-resistance (see Typical Operating Characteristics).

The switches are bidirectional, so the NO_ and COM

pins can be either inputs or outputs.

Power-Supply Sequencing and

Overvoltage Protection

Caution: Do not exceed the absolute maximum rat-

ings because stresses beyond those listed may

cause permanent damage to devices.

Proper power-supply sequencing is recommended for

all CMOS devices. Always apply V+ before applying

analog signals, especially if the analog signal is not

current limited. If this sequencing is not possible, and if

the analog 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 range to a diode

drop (about 0.7V) below V+ (for D1), and a diode drop

above ground (for D2). On-resistance increases slightly

at low supply voltages. Maximum supply voltage (V+)

must not exceed +6V.

Adding protection diode D2 causes the logic threshold

to be shifted relative to GND. TTL compatibility is not

guaranteed when D2 is added.

Protection diodes D1 and D2 also protect against some

overvoltage situations. In the circuit in Figure 1, if the

supply voltage is below the absolute maximum rating,

and if a fault voltage up to the absolute maximum rating

is applied to an analog signal pin, no damage will result.

POSITIVE SUPPLY

COM

NO

D2

D1

GND

Vg

V+

MAX4704

Figure 1. Overvoltage Protection Using Two External Blocking

Diodes

Pin Description

PIN

µMAX

QFN

NAME

FUNCTION

10

1

V+

Positive Supply Voltage

—

2, 8

N.C.

No Connection. Not internally connected.

1

3

NO2

Analog Switch 2. Normally open.

2

4

NO3

Analog Switch 3. Normally open.

3

5

NO1

Analog Switch 1. Normally open.

4

6

INH

Inhibit. Connect to GND for normal operation. Connect to logic-level high to turn

all switches off.

5

7

GND

Ground

6

9

ADDB

Address Decoder Selection B

7

10

ADDA

Address Decoder Selection A

8

11

NO0

Analog Switch 0. Normally open.

9

12

COM

Analog Switch Common Terminal