Low-Voltage, 8-Channel/Dual 4-Channel

Multiplexers with Latchable Inputs

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7

______________________________________________________________Pin Description

2, 17

PIN

MAX382

MAX384

NAME*

FUNCTION

1

WR

WRITE Logic Input

—

1

A0, A1

Address Logic Inputs (see

Truth Tables at end of data sheet)

3

3

EN

Enable Logic Input (see

Truth Tables at end of data sheet)

4

4

V-

Negative Supply Voltage Input. Connect to GND for single-supply operation.

5–8

—

NO1–NO4

Analog Signal Inputs—bidirectional

—

5–8

NO1A–NO4A

Analog Signal Inputs—bidirectional

9

—

COM

Analog Signal Output—bidirectional

—

9, 10

COMA, COMB

Analog Signal Outputs—bidirectional

10–13

—

NO8–NO5

Analog Signal Inputs—bidirectional

—

11–14

NO4B–NO1B

Analog Signal Inputs—bidirectional

14

15

V+

Positive Supply Voltage Input

15

16

GND

Ground

2, 16, 17

A0, A2, A1

Address Logic Inputs (see

Truth Tables at end of data sheet)

—

18

18

RS

RESET Logic Input

__________Applications Information

The internal structures of the MAX382/MAX384 include

translators for the A2/A1/EN/WR/RS digital inputs, latch-

es, and a decode section for channel selection (see

Truth Tables). The analog-signal switches consist of

parallel combinations of N and P MOSFETs.

WRITE (WR) and RESET (RS) strobes are provided for

interfacing with µP-bus lines, alleviating the need for the

µP to provide constant address inputs to the mux to

hold a particular channel (Figures 2–7).

When the WR strobe is in the low state (less than 0.8V)

and the RS strobe is in the high state (greater than

2.4V), the muxes are in the transparent mode—they

act similar to nonlatching devices, such as the

MAX398/MAX399.

When the WR goes high, the previous BCD address

input is latched and held in that state indefinitely.

RS turns off all channels when it is low. All switches stay

off until RS and EN are high and WR is low.

The MAX382/MAX384 work with both single and dual

supplies and function over the +2.4V to +16V single-

supply range. For example, with a single +5V power

supply, analog signals in the 0V to +5V range can be

switched normally. If negative signals around 0V are

expected, a negative supply is needed.

The EN latch allows all switches to be turned off under

program control. This is useful when two or more are

cascaded to build 16-line and larger analog-signal mul-

tiplexers.

*Analog inputs and outputs are names of convenience only. Inputs and outputs are identical and interchangeable.