The ISL3332, ISL3333 are two port interface ICs where each

port can be independently configured as a single

RS-485/422 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

single VCC supply as low as 3.15V. The transceivers are

RS-232 compliant, with the Rx inputs handling up to ±25V.

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 (35μA) mode.

The ISL3333 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

lengths. It also features a logic supply pin (VL) that sets the

VOH level of logic outputs, and the switching points of logic

inputs, to be compatible with another supply voltage in mixed

voltage systems. The QFN also adds RS-232 mode Tx EN

pins (DEN), and active low Rx enable pins (RXEN) to

increase design flexibility. In RS-485 applications, active low

Rx enable pins allow 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

ISL3330, ISL3331 data sheet.

Features

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

RS-485)

? Operates From a Single 3.3V Supply

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

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

? True Flow-Through Pinouts Simplify Board Layouts

? Pb-free (RoHS compliant)

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

? Loopback Mode Facilitates Board Self Test Functions

? User Selectable RS-485 Data Rates (ISL3333 Only)

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

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

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

? Fast RS-232 Data Rate . . . . . . . . . . . . . . . Up to 400kbps

? RS-232 Tx and Rx Enable Pins (ISL3333 Only)

? Small Charge Pump Caps . . . . . . . . . . . . . . . . . 4 x 0.1μF

? Low Current Shutdown Mode. . . . . . . . . . . . . . . . . . .35μA

? QFN Package Saves Board Space (ISL3333 Only)

? Logic Supply Pin (VL) Eases Operation in Mixed Supply

Systems (ISL3333 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