1

®

FN6202.3

ISL81334, ISL41334

±

15kV ESD Protected, 5V, Two Port, Dual

Protocol (RS-232/RS-485) Transceivers

The ISL81334, ISL41334 are two port interface ICs where

each port can be independently configured as a single

RS-485, RS-422 transceiver, or as a dual (2 Tx, 2 Rx) RS-

232 transceiver. With both ports set to the same mode, two

RS-485, RS-422 transceivers, or four RS-232 transceivers

are available.

If either port is in RS-232 mode, the onboard charge pump

generates RS-232 compliant ±5V Tx output levels from a

capacitors are required for the charge pump. The

transceivers are RS-232 compliant, with the Rx inputs

handling up to ±25V, and the Tx outputs handling ±12V.

In RS-485 mode, the transceivers support both the RS-485

and RS-422 differential communication standards. The

receivers feature "full failsafe" operation, so the Rx outputs

remain in a high state if the inputs are open or shorted

together. The transmitters support up to three data rates, two

of which are slew rate limited for problem free

communications. The charge pump disables when both

ports are in RS-485 mode, thereby saving power, minimizing

noise, and eliminating the charge pump capacitors.

Both RS-232 and RS-485 modes feature loopback and

shutdown functions. Loopback internally connects the Tx

outputs to the corresponding Rx input, to facilitate board

level self test implementation. The outputs remain connected

to the loads during loopback, so connection problems (e.g.,

shorted connectors or cables) can be detected. Shutdown

mode disables the Tx and Rx outputs, disables the charge

pumps, and places the IC in a low current (µA) mode.

The ISL41334 is a QFN packaged device that includes two

additional user selectable, lower speed and edge rate

options for EMI sensitive designs, or to allow longer bus

inputs, to be compatible with another supply voltage in mixed

voltage systems. The QFN also adds active low Rx enable

pins to increase design flexibility, allowing Tx/Rx direction

control, via a single signal per port, by connecting the

corresponding DE and RXEN pins together.

For a single port version of these devices, please see the

ISL81387, ISL41387 data sheet.

Features

• ±15kV (HBM) ESD Protected Bus Pins (RS-232 or

RS-485)

• Two Independent Ports, Each User Selectable for RS-232

(2 Transceivers) or RS-485, RS-422 (1 Transceiver)

• Single 5V (10% Tolerance) Supply

• Flow-Through Pinouts Simplify Board Layouts

• Pb-Free (RoHS Compliant)

Immunity in RS-485, RS-422 Networks

• Full Failsafe (Open/Short) Rx in RS-485, RS-422 Mode

• Loopback Mode Facilitates Board Self Test Functions

• User Selectable RS-485 Data Rates (ISL41334 Only)

- Fast Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Mbps

- Slew Rate Limited. . . . . . . . . . . . . . . . . . . . . . . 460kbps

- Slew Rate Limited. . . . . . . . . . . . . . . . . . . . . . . 115kbps

• Fast RS-232 Data Rate . . . . . . . . . . . . . . . Up to 650kbps

• Low Current Shutdown Mode. . . . . . . . . . . . . . . . . . .42µA

• QFN Package Saves Board Space (ISL41334 Only)

Systems (ISL41334 Only)

Applications

• Gaming Applications (e.g., Slot Machines)

• Single Board Computers

• Factory Automation

• Security Networks

• Industrial/Process Control Networks

• Level Translators (e.g., RS-232 to RS-422)

• Point of Sale Equipment

• Dual Channel RS-485 Interfaces

TABLE 1. SUMMARY OF FEATURES

PART NUMBER

NO. OF

PORTS

PACKAGE OPTIONS

RS-485 DATA

RATE (bps)

RS-232 DATA

RATE (kbps)

ACTIVE H or L

Rx ENABLE?

LOW POWER

SHUTDOWN?

ISL81334

2

28 Ld SOIC, 28 Ld SSOP

20M

650

NO

NONE

YES

ISL41334

2

40 Ld QFN (6mmx6mm)

20M, 460k, 115k

650

YES

L

YES

Data Sheet

November 21, 2007

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

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