±15kV ESD-Protected, Slew-Rate-Limited,

Low-Power, RS-485/RS-422 Transceivers

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9

__________Function Tables

(MAX481E/MAX483E/MAX485E/MAX487E/MAX1487E)

Table 1. Transmitting

Table 2. Receiving

INPUTS

OUTPUT

RE

DE

A-B

RO

0

0

0

1

0

0

0

0

> +0.2V

< -0.2V

Inputs open

X

1

0

1

High-Z

*

X = Don't care

High-Z = High impedance

INPUTS

OUTPUTS

RE

DE

DI

Z

Y

X

X

0

1

1

1

0

0

1

0

X

X

0

1

High-Z

High-Z

*

1

0

High-Z

High-Z

*

X = Don't care

High-Z = High impedance

__________Applications Information

The MAX481E/MAX483E/MAX485E/MAX487E–MAX491E

and MAX1487E are low-power transceivers for RS-485

and RS-422 communications. These “E” versions of the

MAX481, MAX483, MAX485, MAX487–MAX491, and

MAX1487 provide extra protection against ESD. The

rugged MAX481E, MAX483E, MAX485E, MAX497E–

MAX491E, and MAX1487E are intended for harsh envi-

ronments where high-speed communication is important.

These devices eliminate the need for transient suppres-

sor diodes and the associated high capacitance loading.

The standard (non-“E”) MAX481, MAX483, MAX485,

MAX487–MAX491, and MAX1487 are recommended for

applications where cost is critical.

The MAX481E, MAX485E, MAX490E, MAX491E, and

MAX1487E can transmit and receive at data rates up to

2.5Mbps, while the MAX483E, MAX487E, MAX488E,

and MAX489E are specified for data rates up to

250kbps. The MAX488E–MAX491E are full-duplex

transceivers, while the MAX481E, MAX483E, MAX487E,

and MAX1487E are half-duplex. In addition, driver-

enable (DE) and receiver-enable (RE) pins are included

on the MAX481E, MAX483E, MAX485E, MAX487E,

MAX489E, MAX491E, and MAX1487E. When disabled,

the driver and receiver outputs are high impedance.

±15kV ESD Protection

As with all Maxim devices, ESD-protection structures

are incorporated on all pins to protect against electro-

static discharges encountered during handling and

assembly. The driver outputs and receiver inputs have

extra protection against static electricity. Maxim’s engi-

neers developed state-of-the-art structures to protect

these pins against ESD of ±15kV without damage. The

ESD structures withstand high ESD in all states: normal

operation, shutdown, and powered down. After an ESD

event, Maxim’s MAX481E, MAX483E, MAX485E,

MAX487E–MAX491E, and MAX1487E keep working

without latchup.

ESD protection can be tested in various ways; the

transmitter outputs and receiver inputs of this product

family are characterized for protection to ±15kV using

the Human Body Model.

Other ESD test methodologies include IEC10004-2 con-

tact discharge and IEC1000-4-2 air-gap discharge (for-

merly IEC801-2).

ESD Test Conditions

ESD performance depends on a variety of conditions.

Contact Maxim for a reliability report that documents

test set-up, test methodology, and test results.

Human Body Model

Figure 4 shows the Human Body Model, and Figure 5

shows the current waveform it generates when dis-

charged into a low impedance. This model consists of

a 100pF capacitor charged to the ESD voltage of inter-

est, which is then discharged into the test device

through a 1.5k

Ω resistor.

IEC1000-4-2

The IEC1000-4-2 standard covers ESD testing and per-

formance of finished equipment; it does not specifically

refer to integrated circuits (Figure 6).