DATASHEET
ISL3330, ISL3331
3.3V, ±15kV ESD Protected, 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 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.
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, 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.
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
(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'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
ISL3332/ISL3333 data sheet.
FN6361
Rev 0.00
May 20, 2008
Features
• User Selectable RS-232 or RS-485/RS-422 Interface Port
(Two RS-232 Transceivers or One RS-485/RS-422
Transceiver)
• Operates From a Single 3.3V Supply
• ±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)
• 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)
• Logic Supply Pin (V
L
) Eases Operation in Mixed Supply
Systems (ISL3331 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
Related Literature
• Application Note AN1401 “Implementing a Three Pin,
Half-Duplex, Dual Protocol Interface”
TABLE 1. SUMMARY OF FEATURES
PART
NUMBER
ISL3330
ISL3331
NO. OF
PORTS
1
1
PACKAGE OPTIONS
20 Ld SSOP
40 Ld QFN (6mmx6mm)
RS-485 DATA
RATE (bps)
20M, 460k
20M, 460k, 115k
RS-232 DATA
RATE (kbps)
400
400
V
L
PIN?
No
Yes
ACTIVE H or L
Rx ENABLE?
H
Both
LOW POWER
SHUTDOWN?
Yes
Yes
FN6361 Rev 0.00
May 20, 2008
Page 1 of 25
ISL3330, ISL3331
Ordering Information
PART NUMBER (NOTE)
ISL3330IAZ
ISL3330IAZ-T*
ISL3331IRZ
ISL3331IRZ-T*
PART MARKING
3330 IAZ
3330 IAZ
ISL3331IRZ
ISL3331IRZ
TEMP. RANGE (°C)
-40 to +85
-40 to +85
-40 to +85
-40 to +85
PACKAGE (Pb-Free)
20 Ld SSOP
20 Ld SSOP (Tape and Reel)
40 Ld 6x6 QFN
40 Ld 6x6 QFN (Tape and Reel)
PKG. DWG. #
M20.209
M20.209
L40.6x6
L40.6x6
*Please refer to TB347 for details on reel specifications.
NOTE: These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100%
matte tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations).
Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J
STD-020.
Pinouts
ISL3330
(20 LD SSOP)
TOP VIEW
C1+ 1
C1- 2
V+
3
20 C2+
19 C2-
18 V
CC
17 R
A
16 R
B
15 D
Y
14 D
Z
/SLEW
13 ON
12 RXEN
11 V-
A 4
B 5
Y 6
Z 7
485/232 8
DEN 9
GND 10
ISL3331
(40 LD QFN)
TOP VIEW
V
CC
C1+
C2+
C1-
C2-
NC
NC
NC
NC
32
V
L
31
30 R
A
29 R
B
28 D
Y
27 D
Z
/SLEW
26 NC
25 NC
24 NC
23 NC
22 NC
21 ON
11
485/232
12
DEN
13
NC
14
SPB
15
GND
16
GND
17
RXEN
18
NC
19
V-
20
RXEN
40
V+
A
B
Y
Z
NC
NC
NC
NC
NC
1
2
3
4
5
6
7
8
9
10
39
38
37
36
35
34
33
FN6361 Rev 0.00
May 20, 2008
Page 2 of 25
ISL3330, ISL3331
TABLE 2. ISL3330 FUNCTION TABLE
INPUTS
485/232
0
0
0
0
0
0
0
X
1
1
1
1
1
NOTES:
1. Charge pumps are on if in RS-232 mode and ON or DEN or RXEN are high.
2. Loopback is enabled when ON = 0, and DEN = RXEN = 1.
ON
1
1
1
1
0
0
0
0
1
X
X
1
0
RXEN
0
0
1
1
0
1
1
0
0
0
1
1
1
DEN SLEW
0
1
0
1
1
0
1
0
0
1
0
1
1
N/A
N/A
N/A
N/A
N/A
N/A
N/A
X
X
1/0
X
1/0
1/0
RECEIVER
OUTPUTS
R
A
High-Z
High-Z
ON
ON
High-Z
High-Z
ON
High-Z
High-Z
High-Z
ON
ON
ON
R
B
High-Z
High-Z
ON
ON
High-Z
ON
ON
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
DRIVER OUTPUTS
Y
High-Z
ON
High-Z
ON
ON
ON
ON
High-Z
High-Z
ON
High-Z
ON
ON
Z
High-Z
ON
High-Z
ON
High-Z
High-Z
ON
High-Z
High-Z
ON
High-Z
ON
ON
DRIVER
SPEED
(Mbps)
-
0.46
-
0.46
0.46
0.46
0.46
-
-
20/0.46
-
20/0.46
20/0.46
CHARGE
PUMPS
(Note 1)
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
OFF
OFF
OFF
OFF
LOOPBACK
(Note 2)
OFF
OFF
OFF
OFF
OFF
OFF
ON
OFF
OFF
OFF
OFF
OFF
ON
MODE
RS-232
RS-232
RS-232
RS-232
RS-232
RS-232
RS-232
Shutdown
RS-485
RS-485
RS-485
RS-485
RS-485
ISL3330 Truth Tables
RS-232 TRANSMITTING MODE
INPUTS (ON = 1)
485/232
0
0
0
0
0
DEN
1
1
1
1
0
D
Y
0
0
1
1
X
D
Z
0
1
0
1
X
OUTPUTS
Y
1
1
0
0
High-Z
Z
1
0
1
0
High-Z
485/232
1
1
1
1
1
DEN
1
1
1
1
0
RS-485 TRANSMITTING MODE
INPUTS (ON = 1)
D
Y
0
1
0
1
X
SLEW
1
1
0
0
X
Y
1
0
1
0
OUTPUTS
Z
0
1
0
1
DATA RATE
(Mbps)
20
20
0.46
0.46
-
High-Z High-Z
RS-232 RECEIVING MODE
INPUTS (ON = 1)
485/232
0
0
0
0
0
0
RXEN
1
1
1
1
1
0
A
0
0
1
1
Open
X
B
0
1
0
1
Open
X
OUTPUT
R
A
1
1
0
0
1
High-Z
R
B
1
0
1
0
1
High-Z
485/232
1
1
1
1
RXEN
1
1
1
0
RS-485 RECEIVING MODE
INPUTS (ON = 1)
B-A
-40mV
-200mV
Open or Shorted together
X
OUTPUT
R
A
1
0
1
High-Z
R
B
High-Z
High-Z
High-Z
High-Z
FN6361 Rev 0.00
May 20, 2008
Page 3 of 25
ISL3330, ISL3331
TABLE 3. ISL3331 FUNCTION TABLE
INPUTS
RXEN
AND/OR
RXEN
1 and 0
1 and 0
0 or 1
0 or 1
1 and 0
0 or 1
0 or 1
1 and 0
1 and 0
1 and 0
1 and 0
0 or 1
0 or 1
0 or 1
0 or 1
0 or 1
RECEIVER
OUTPUTS
DRIVER
OUTPUTS
DRIVER
DATA
RATE
(Mbps)
-
0.46
-
0.46
0.46
0.46
0.46
-
-
0.46/0.115
20
-
0.46/0.115
20
0.46/0.115
20
485/232
0
0
0
0
0
0
0
X
1
1
1
1
1
1
1
1
NOTES:
ON
1
1
1
1
0
0
0
0
1
X
X
X
1
1
0
0
DEN
0
1
0
1
1
0
1
0
0
1
1
0
1
1
1
1
SLEW
N/A
N/A
N/A
N/A
N/A
N/A
N/A
X
X
0
1
X
0
1
0
1
SPB
N/A
N/A
N/A
N/A
N/A
N/A
N/A
X
X
1/0
X
X
1/0
X
1/0
X
R
A
High-Z
High-Z
ON
ON
High-Z
High-Z
ON
High-Z
High-Z
High-Z
High-Z
ON
ON
ON
ON
ON
R
B
High-Z
High-Z
ON
ON
High-Z
ON
ON
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
Y
High-Z
ON
High-Z
ON
ON
ON
ON
High-Z
High-Z
ON
ON
High-Z
ON
ON
ON
ON
Z
High-Z
ON
High-Z
ON
High-Z
High-Z
ON
High-Z
High-Z
ON
ON
High-Z
ON
ON
ON
ON
CHARGE
PUMPS
(Note 3)
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
MODE
RS-232
RS-232
RS-232
RS-232
RS-232
RS-232
RS-232 (Note 4)
Shutdown
RS-485
RS-485
RS-485
RS-485
RS-485
RS-485
RS-485 (Note 4)
RS-485 (Note 4)
3. Charge pumps are on if in RS-232 mode and ON or DEN or RXEN is high, or RXEN is low.
4. Loopback is enabled when ON = 0, and DEN = 1, and (RXEN = 1 or RXEN = 0).
ISL3331 Truth Tables
RS-232 TRANSMITTING MODE
INPUTS (ON = 1)
485/232
0
0
0
0
0
DEN
1
1
1
1
0
D
Y
0
0
1
1
X
D
Z
0
1
0
1
X
OUTPUTS
Y
1
1
0
0
High-Z
Z
1
0
1
0
High-Z
485/232
1
1
1
1
DEN
1
1
1
0
RS-485 TRANSMITTING MODE
INPUTS (ON = 1)
SLEW
0
0
1
X
SPB
0
1
X
X
D
Y
0/1
0/1
0/1
X
OUTPUTS
Y
1/0
1/0
1/0
Z
0/1
0/1
0/1
DATA
Mbps
0.115
0.460
20
-
High-Z High-Z
RS-485 RECEIVING MODE
INPUTS (ON = 1)
OUTPUT
B-A
-40mV
-200mV
Open or Shorted
together
X
R
A
1
0
1
R
B
High-Z
High-Z
High-Z
RS-232 RECEIVING MODE
INPUTS (ON = 1)
485/232 RXEN and/or RXEN
0
0
0
0
0
0
0 or 1
0 or 1
0 or 1
0 or 1
0 or 1
1 and 0
A
0
0
1
1
Open
X
B
0
1
0
1
Open
X
OUTPUT
R
A
1
1
0
0
1
R
B
1
0
1
0
1
485/232 RXEN and/or RXEN
1
1
1
1
0 or 1
0 or 1
0 or 1
1 and 0
High-Z High-Z
High-Z High-Z
FN6361 Rev 0.00
May 20, 2008
Page 4 of 25
ISL3330, ISL3331
Pin Descriptions
PIN
485/232
DEN
GND
NC
ON
MODE
BOTH
BOTH
BOTH
BOTH
BOTH
FUNCTION
Interface Mode Select input. High for RS-485 Mode and low for RS-232 Mode.
Driver output enable. The driver outputs, Y and Z, are enabled by bringing DEN high. They are high impedance when DEN
is low.
Ground connection.
No Connection.
In RS-232 mode only, ON high enables the charge pumps. ON low, with DEN and RXEN low (and RXEN high if QFN), turns
off the charge pumps (in RS-232 mode), and in either mode places the device in low power shutdown. In both modes, when
ON is low, and DEN is high, and RXEN is high or RXEN is low, loopback is enabled.
Receiver output enable. Rx is enabled when RXEN is high; Rx is high impedance when RXEN is low and, if using the QFN
package, RXEN is high. When using the QFN and the active high Rx enable function, RXEN should be high or floating.
Active low receiver output enable. Rx is enabled when RXEN is low; Rx is high impedance when RXEN is high and RXEN
is low. (i.e., to use active low Rx enable function, tie RXEN to GND). For single signal Tx/Rx direction control, connect RXEN
to DEN. Internally pulled high. (QFN only)
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)
RXEN
RXEN
BOTH
BOTH
V
CC
V
L
A
BOTH
BOTH
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
/SLEW 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 Slew rate control. With the SLEW pin high, the drivers run at the maximum slew rate (20Mbps). With the SLEW pin low, the
drivers run at a reduced slew rate (460kbps). The QFN version works in conjunction with SPB to select one of three RS-485
data rates. Internally pulled high in RS-485 mode.
SPB
R
A
RS-485 Speed control. Works in conjunction with the SLEW pin to select the 20Mbps, 460kbps or 115kbps RS-485 data rate.
Internally pulled high. (QFN only)
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. Output is high impedance, and unaffected by RXEN and 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.
C1+
C1-
C2+
C2-
V+
V-
RS-232 External capacitor (voltage doubler) is connected to this lead. Not needed in RS-485 Mode.
RS-232 External capacitor (voltage doubler) is connected to this lead. Not needed in RS-485 Mode.
RS-232 External capacitor (voltage inverter) is connected to this lead. Not needed in RS-485 Mode.
RS-232 External capacitor (voltage inverter) is connected to this lead. Not needed in RS-485 Mode.
RS-232 Internally generated positive RS-232 transmitter supply (+5.5V). C3 not needed in RS-485 Mode.
RS-232 Internally generated negative RS-232 transmitter supply (-5.5V). C4 not needed in RS-485 Mode.
FN6361 Rev 0.00
May 20, 2008
Page 5 of 25
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