1

®

FN6201.3

ISL81387, ISL41387

±

15kV ESD Protected, 5V, Dual Protocol

(RS-232/RS-485) Transceivers

These devices are BiCMOS interface ICs that are user

configured as either a single RS-422, RS-485 differential

transceiver, or as a dual (2 Tx, 2 Rx) RS-232 transceiver.

In RS-232 mode, the on-board charge pump generates

RS-232 compliant ±5V Tx output levels, from a supply as low

as 4.5V. Four small 0.1µF 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

RS-485 receiver features "full failsafe" operation, so the Rx

output remains in a high state if the inputs are open or

shorted together. The RS-485 transmitter supports up to

three data rates, two of which are slew rate limited for

problem free communications. The charge pump disables in

RS-485 mode, thereby saving power, minimizing noise, and

eliminating the charge pump capacitors.

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

shutdown functions. The loopback mode internally connects

the Tx outputs to the corresponding Rx input, which

facilitates the implementation of board level self test

functions. The outputs remain connected to the loads during

loopback, so connection problems (e.g., shorted connectors

or cables) can be detected. The shutdown mode disables

the Tx and Rx outputs, disables the charge pump if in

RS-232 mode, and places the IC in a low current (20µA)

mode.

The ISL41387 is a QFN packaged device that offers

additional functionality, including a lower speed and edge

rate option (115kbps) for EMI sensitive designs, or to allow

longer bus lengths. It also features a logic supply voltage pin

switching points of logic inputs, to be compatible with

another supply voltage in mixed voltage systems. The QFN's

choice of active high or low Rx enable pins increases design

flexibility, allowing Tx/Rx direction control via a single signal

by connecting DEN and RXEN together.

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

ISL81334, ISL41334 data sheet.

Features

• 5V Powered, User Selectable RS-232 or RS-485, RS-422

Interface Port (Two RS-232 Transceivers or One RS-485,

RS-422 Transceiver)

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

RS-485)

• 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 . . . . . . . . . . 20Mbps

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

- Slew Rate Limited (ISL41387 Only) . . . . . . . . . 115kbps

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

• Low Current Shutdown Mode. . . . . . . . . . . . . . . . . . .35µA

• QFN Package Saves Board Space (ISL41387 Only)

Systems (ISL41387 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

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?

ISL81387

1

20 Ld SOIC, 20 Ld SSOP

20M, 460k

650

NO

H

YES

ISL41387

1

40 Ld QFN (6mmx6mm)

20M, 460k, 115k

650

YES

BOTH

YES

Data Sheet

November 21, 2007

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

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