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