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ISL3332, ISL3333
Data Sheet
May 27, 2008
FN6362.0
3.3V, ±15kV ESD Protected, Two Port, Dual
Protocol (RS-232/RS-485) Transceivers
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 V
CC
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 (V
L
) that sets the
V
OH
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 (V
L
) 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
TABLE 1. SUMMARY OF FEATURES
NO. OF
PART NUMBER PORTS PACKAGE OPTIONS
ISL3332
ISL3333
2
2
28 Ld SSOP
RS-485 DATA
RATE (bps)
20M
RS-232 DATA
RATE (kbps) V
L
PIN?
400
400
NO
YES
RS-232 Tx
ENABLE?
NO
YES
ACTIVE H or L LOW POWER
Rx ENABLE? SHUTDOWN?
NONE
L
YES
YES
40 Ld QFN (6 x 6mm) 20M, 460k, 115k
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774
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Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright © Intersil Americas Inc. 2008. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
ISL3332, ISL3333
Pin Descriptions
PIN
GND
LB
NC
ON/OFF
RXEN
SEL
V
CC
V
L
DEN
A
MODE
BOTH
BOTH
BOTH
BOTH
BOTH
BOTH
BOTH
BOTH
Ground connection.
Enables loopback mode when low. Internally pulled-high.
No Connection.
If either port is in RS-232 mode, a low on ON/OFF disables the charge pumps. In either mode, a low disables all the outputs,
and places the device in low power shutdown. Internally pulled-high. ON = 1 for normal operation.
Active low receiver output enable. The corresponding port’s Rx is enabled when RXEN is low; Rx is high impedance when
RXEN is high. Internally pulled low. (QFN only)
Interface Mode Select input. High puts corresponding port in RS-485 Mode, while a low puts it in RS-232 Mode.
System power supply input (3.3V).
Logic-Level Supply. All TTL/CMOS inputs and outputs are powered by this supply. QFN logic input pins that are externally
tied high in an application, should use the V
L
supply for the high voltage level. (QFN only)
FUNCTION
RS-232 Active high driver output enable. The corresponding port’s 232 mode drivers are enabled when DEN is high; drivers are
disabled when DEN is low. Internally pulled high. (QFN only).
RS-232 Receiver input with
±15kV
ESD protection. A low on A forces R
A
high; A high on A forces R
A
low.
RS-485 Inverting receiver input with
±15kV
ESD protection.
B
RS-232 Receiver input with
±15kV
ESD protection. A low on B forces R
B
high; A high on B forces R
B
low.
RS-485 Noninverting receiver input with
±15kV
ESD protection.
D
Y
RS-232 Driver input. A low on D
Y
forces output Y high. Similarly, a high on D
Y
forces output Y low.
RS-485 Driver input. A low on D
Y
forces output Y high and output Z low. Similarly, a high on D
Y
forces output Y low and output Z high.
D
Z
/ DE
RS-232 Driver input. A low on D
Z
forces output Z high. Similarly, a high on D
Z
forces output Z low.
RS-485 Driver output enable (DE). The driver outputs, Y and Z, are enabled by bringing DE high. They are high impedance when
DE is low. Internally pulled high when port selected for RS-485 mode.
R
A
RS-232 Receiver output.
RS-485 Receiver output: If B > A by at least -40mV, R
A
is high; If B < A by -200mV or more, R
A
is low; R
A
= High if A and B are
unconnected (floating) or shorted together (i.e., full fail-safe).
R
B
RS-232 Receiver output.
RS-485 Not used. Internally pulled-high, and unaffected by RXEN.
Y
RS-232 Driver output with
±15kV
ESD protection.
RS-485 Inverting driver output with
±15kV
ESD protection.
Z
RS-232 Driver output with
±15kV
ESD protection.
RS-485 Noninverting driver output with
±15kV
ESD protection.
SP
C1+
C1-
C2+
C2-
V+
V-
RS-485 Speed control. Internally pulled-high. (QFN only)
RS-232 External capacitor (voltage doubler) is connected to this lead. Not needed if both ports in RS-485 Mode.
RS-232 External capacitor (voltage doubler) is connected to this lead. Not needed if both ports in RS-485 Mode.
RS-232 External capacitor (voltage inverter) is connected to this lead. Not needed if both ports in RS-485 Mode.
RS-232 External capacitor (voltage inverter) is connected to this lead. Not needed if both ports in RS-485 Mode.
RS-232 Internally generated positive RS-232 transmitter supply (+5.5V). C3 not needed if both ports in RS-485 Mode.
RS-232 Internally generated negative RS-232 transmitter supply (-5.5V). C4 not needed if both ports in RS-485 Mode.
5
FN6362.0
May 27, 2008
Embedded System
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