ISL3330, ISL3331
®
Data Sheet
May 20, 2008
FN6361.0
3.3V, ±15kV ESD Protected, Dual Protocol
Features
(RS-232/RS-485) Transceivers
• User Selectable RS-232 or RS-485/RS-422 Interface Port
(Two RS-232 Transceivers or One RS-485/RS-422
Transceiver)
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.
• Operates From a Single 3.3V Supply
In RS-232 mode, the on-board charge pump generates
RS-232 compliant ±5V Tx output levels, from a supply as low
as 3.15V. 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.
• ±15kV (HBM) ESD Protected Bus Pins (RS-232 or
RS-485)
• 5V Tolerant Logic Inputs
• True Flow-Through Pinouts Simplify Board Layouts
• Pb-Free (RoHS Compliant)
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.
• 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 (ISL3331 Only) . . . . . . . . . . 115kbps
• Fast RS-232 Data Rate . . . . . . . . . . . . . . . Up to 400kbps
• Low Current Shutdown Mode. . . . . . . . . . . . . . . . . . 30µA
• QFN Package Saves Board Space (ISL3331 Only)
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, where
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 (30µA) mode.
• Logic Supply Pin (V ) Eases Operation in Mixed Supply
L
Systems (ISL3331 Only)
Applications
• Gaming Applications (e.g., Slot machines)
• Single Board Computers
• Factory Automation
The ISL3331 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
• Security Networks
• Industrial/Process Control Networks
• Level Translators (e.g., RS-232 to RS-422)
• Point of Sale Equipment
(V ) that sets the V
level of logic outputs, and the
L
OH
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.
Related Literature
• Application Note AN1401 “Implementing a Three Pin,
Half-Duplex, Dual Protocol Interface”
For a dual port version of these devices, please see the
ISL3332/ISL3333 data sheet.
TABLE 1. SUMMARY OF FEATURES
PART
NUMBER
NO. OF
PORTS
RS-485 DATA
RATE (bps)
RS-232 DATA
RATE (kbps)
ACTIVE H or L
Rx ENABLE?
LOW POWER
SHUTDOWN?
PACKAGE OPTIONS
V
PIN?
L
ISL3330
ISL3331
1
1
20 Ld SSOP
20M, 460k
400
400
No
H
Yes
Yes
40 Ld QFN (6mmx6mm) 20M, 460k, 115k
Yes
Both
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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1
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