MAX13413EESA+T Datasheet MAX13413EESA+, MAX13412EESA+, MAX13412EESA+T | P19-P21

ESD Test Conditions

ESD performance depends on a variety of conditions.

Contact Maxim for a reliability report that documents

test setup, test methodology, and test results.

Human Body Model

Figure 8a shows the Human Body Model, and Figure

8b 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 1.5kΩ resistor.

Applications Information

Typical Applications

The MAX13410E–MAX13415E transceivers are designed

for half-duplex, bidirectional data communications on

multipoint bus transmission lines. To minimize reflections,

terminate the line at both ends in its characteristic

impedance, and keep stub lengths off the main line as

short as possible. The slew-rate-limited MAX13410E/

MAX13412E/MAX13414E are more tolerant of imperfect

termination.

Typical Application Circuit for the

MAX13410E and MAX13411E

This application circuit shows the MAX13410E/

MAX13411E being used in an isolated application (see

Figure 9). The MAX13410E/MAX13411E use the industry-

standard pin out but do not have a V

REG

output for

biasing external circuitry. The positive temperature coef-

ficient (PTC) and transient voltage suppressor (TVS)

clamp circuit on the RS-485 outputs are intended to pro-

vide overvoltage fault protection and are optional based

on the requirements of the design.

Typical Application Circuit for the

MAX13412E and MAX13413E

This application circuit shows the MAX13412E and

MAX13413E being used in an isolated application

where the AutoDirection feature is implemented to

reduce the number of optical isolators to two (see

Figure 10). The MAX13412E/MAX13413E provide a

REG

output that can be used to power external circuit-

ry up to 20mA.

Typical Application Circuit for the

MAX13414E and MAX13415E

This application circuit shows the MAX13414E/

MAX13415E being used in an isolated application using

an unregulated power supply with three optical isolators

(see Figure 11). The MAX13414E/MAX13415E provide a

REG

output that can be used to power external circuitry

up to 20mA.

256 Transceivers on the Bus

The RS-485 standard specifies the load each receiver

places on the bus in terms of unit loads. An RS-485-

compliant transmitter can drive 32 one-unit load

receivers when used with a 120Ω cable that is terminat-

ed on both ends over a -7V to +12V common-mode

range. The MAX13410E–MAX13415E are specified as

1/8 unit loads. This means a compliant transmitter can

drive up to 256 devices of the MAX13410E–MAX13415E.

Reducing the common mode, and/or changing the char-

acteristic impedance of the cable, changes the maxi-

mum number of receivers that can be used. Refer to the

TIA/EIA-485 specification for further details.

Proper Termination and Cabling/

Wiring Configurations

When the data rates for RS-485 are high relative to the

cable length it is driving, the system is subject to proper

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout

Regulator and AutoDirection Control

______________________________________________________________________________________ 19

CHARGE-CURRENT-

LIMIT RESISTOR

DISCHARGE

RESISTANCE

STORAGE

CAPACITOR

100pF

1MΩ

1500Ω

HIGH-

VOLTAGE

SOURCE

DEVICE

UNDER

TEST

Figure 8a. Human Body ESD Test Model

100%

90%

36.8%

TIME

CURRENT WAVEFORM

PEAK-TO-PEAK RINGING

(NOT DRAWN TO SCALE)

10%

AMPS

Figure 8b. Human Body Current Waveform

MAX13410E–MAX13415E

transmission line design. In most cases, a single, con-

trolled-impedance cable or trace should be used and

should be properly terminated on both ends with the

characteristic impedance of the cable/trace. RS-485

transceivers should be connected to the cable/ traces

with minimum-length wires to prevent stubs. Star config-

urations and improperly terminated cables can cause

data loss. Refer to the

Application Notes

section of the

Maxim website or to TIA/EIA publication TSB-89-A for

further information. While proper termination is always

desirable, in some cases, such as when data rates are

very low, it may be desirable and advantageous to not

properly terminate the cables. In such cases, it is up to

the designer to ensure that the improper termination

and resultant reflections (etc.) will not corrupt the data.

Reduced EMI and Reflections

The MAX13410E/MAX13412E/MAX13414E feature

reduced slew-rate drivers that minimize EMI and reduce

reflections caused by improperly terminated cables,

allowing error-free data transmission up to 500kbps.

Low-Power Shutdown Mode

Low-power shutdown mode is initiated in the

MAX13410E/MAX13411E by driving DE low and driving

RE high. In shutdown, the devices draw 65µA (typ) of

supply current.

The devices are guaranteed not to enter shutdown if

DE is low (while RE is high) for less than 50ns. If the

inputs are in this state for at least 700ns, the devices

are guaranteed to enter shutdown.

Enable times t

and t

(see the switching character-

istics table) assume the devices were not in a low-power

shutdown state. Enable times t

ZH(SHDN)

and t

ZL(SHDN)

assume the devices were in shutdown state. It takes dri-

vers and receivers longer to become enabled from low-

power shutdown mode (t

ZH(SHDN)

, t

ZL(SHDN)

) than from

driver/receiver disable mode (t

, t

Line Length

The Telecommunications Industry Association (TIA) pub-

lished the document TSB-89-A:

Application Guidelines

for TIA/EIA-485-A

, which is a good reference for deter-

mining maximum data rate vs. line length.

Isolated RS-485 Interface

An isolated RS-485 interface electrically isolates different

nodes on the bus to protect the bus from problems due

to high common-mode voltages that exceed the RS-485

common-mode voltage range, conductive noise, and

RS-485 Transceiver with Integrated Low-Dropout

Regulator and AutoDirection Control

20 ______________________________________________________________________________________

GND

MAX13410E

MAX13411E

LDO

ISO_V

MCU AND

CIRCUITRY

SYS

ISO_V

UNREGULATED ISOLATED

POWER SUPPLY

0.1μF

ISO_V

Figure 9. Typical Application Circuit for the MAX13410E/MAX13411E

ground loops. The typical application circuits show an

isolated RS-485 interface using the MAX13410E–

MAX13415E. The transceiver is powered separately from

the controlling circuitry. The AutoDirection feature of the

MAX13412E/MAX13413E (see the

AutoDirection Circuitry

section) requires only two optocouplers to electrically

isolate the transceiver.

An isolated RS-485 interface electrically isolates differ-

ent nodes on the bus to protect the bus from problems

due to high common-mode voltages that exceed the

RS-485 common-mode voltage range. An isolated RS-

485 interface has two additional design challenges not

normally associated with RS-485 design. These are 1)

isolating the control signals and 2) getting isolated

power to the transceiver. Optical isolators are the most

common way of getting the control signals across the

isolation barrier.

Isolated power is typically done using a transformer in

either a push-pull or flyback configuration. The MAX845

is an example of an inexpensive, unregulated push-pull

converter (see Figure 12). While in theory, the output of

an unregulated push-pull converter is predictable, the

output voltage can vary significantly due to the non-ideal

characteristics of the transformer, load variations, and

temperature drift of the diodes, etc. Variances of ±20%

or more would not be uncommon. This would require the

addition of a linear regulator to get standard RS-485

transceivers to work. Since the MAX13410E–

MAX13415E have the linear regulator built in, this exter-

nal regulator and its associated cost and size penalties

are not necessary. A nominal +7.5V output with a ±20%

tolerance would provide a +6V to +9V supply voltage.

This is well within the operating range of the

MAX13410E–MAX13415E. If the output tolerance is even

greater than ±20%, adjust the design of the power sup-

ply for a higher output voltage to ensure the minimum

input voltage requirements are met.

Flyback converters are typically regulated. A TL431 type

error amplifier and an optical isolator usually close the

loop. The MAX5021 is an example of a small, inexpen-

sive, flyback controller (see Figure 13). While the prima-

ry output of the flyback converter is tightly regulated,

secondary outputs will not be. As with the unregulated

push-pull converter, the MAX13410E–MAX13415E are

ideally suited for use with these secondary outputs.

MAX13410E–MAX13415E

RS-485 Transceiver with Integrated Low-Dropout

Regulator and AutoDirection Control

GND

REG

MAX13412E

MAX13413E

LDO

ISO_V

MCU AND

CIRCUITRY

SYS

0.1μF

ISO_V

1μF

DETECT

CIRCUIT

ISO_V

UNREGULATED ISOLATED

POWER SUPPLY

Figure 10. Typical Application Circuit for the MAX13412E/MAX13413E

______________________________________________________________________________________ 21

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P21 P22-P24

MAX13413EESA+T

Mfr. #:

Buy MAX13413EESA+T

Manufacturer:

Maxim Integrated

Description:

RS-485 Interface IC Ic Txrx RS-485 Ldo/Ctrl

Lifecycle:

New from this manufacturer.

Delivery:

DHL FedEx Ups TNT EMS

Payment:

T/T Paypal Visa MoneyGram Western Union

MAX13413EESA+T

MAX13413EESA+T

Products related to this Datasheet