1
FN6202.1
ISL81334, ISL41334
15kV ESD Protected, Two Port, Dual
Protocol Transceivers
The ISLX1334 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-485/422
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 4.5V. Four small 0.1
F
capacitors are required for the charge pump. The
transceivers are RS-232 compliant, with the Rx inputs
handling up to
25V, and the Tx outputs handling 12V.
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 (
A) mode.
The ISL41334 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 active low Rx enable
pins to increase design flexibility, allowing Tx/Rx direction
control, via a single signal per port, by connecting the
corresponding DE and RE pins together.
For a single port version of these devices, please see the
ISL81387/ ISL41387 data sheet.
Features
15kV (HBM) ESD Protected Bus Pins (RS-232 or
RS-485)
Two Independent Ports, Each User Selectable for RS-232
(2 Transceivers) or RS-485/422 (1 Transceiver)
Flow-Through Pinouts Simplify Board Layouts
Pb-Free Plus Anneal Available (RoHS Compliant)
Large (2.7V) Differential V
OUT
for Improved Noise
Immunity in RS-485/422 Networks
Full Failsafe (Open/Short) Rx in RS-485/422 Mode
Loopback Mode Facilitates Board Self Test Functions
User Selectable RS-485 Data Rates (ISL41334 Only)
- Fast Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Mbps
- Slew Rate Limited. . . . . . . . . . . . . . . . . . . . . . . 460kbps
- Slew Rate Limited. . . . . . . . . . . . . . . . . . . . . . . 115kbps
Fast RS-232 Data Rate . . . . . . . . . . . . . . . Up to 650kbps
Low Current Shutdown Mode. . . . . . . . . . . . . . . . . . .42
A
QFN Package Saves Board Space (ISL41334 Only)
Logic Supply Pin (V
L
) Eases Operation in Mixed Supply
Systems (ISL41334 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
PART NUMBER
NO. OF
PORTS
PACKAGE OPTIONS
RS-485 DATA
RATE (bps)
RS-232 DATA
RATE (kbps)
V
L
PIN?
ACTIVE H or L
Rx ENABLE?
LOW POWER
SHUTDOWN?
ISL81334
2
28 Ld SOIC, 28 Ld SSOP
20M
650
NO
NONE
YES
ISL41334
2
40 Ld QFN (6 x 6mm)
20M, 460k, 115k
650
YES
L
YES
Data Sheet
December 20, 2005
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774
|
Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2005. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
5
FN6202.1
December 20, 2005
Pin Descriptions
PIN
MODE
FUNCTION
GND
BOTH
Ground connection.
LB
BOTH
Enables loopback mode when low. Internally pulled-high.
NC
BOTH
No Connection.
ON/OFF
BOTH
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.
RXEN
BOTH
Active low receiver output enable. Rx is enabled when RXEN is low; Rx is high impedance when RXEN is high. Internally
pulled low. (QFN only)
SEL
BOTH
Interface Mode Select input. High puts corresponding port in RS-485 Mode, while a low puts it in RS-232 Mode.
V
CC
BOTH
System power supply input (5V).
V
L
BOTH
Logic-Level Supply. All TTL/CMOS inputs and outputs are powered by this supply. (QFN only)
A
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
RS-232 Driver input. A low on D
Z
forces output Z high. Similarly, a high on D
Z
forces output Z low.
DE
RS-485 Driver output enable. 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
RS-485 Speed control. Internally pulled-high. (QFN only)
C1+
RS-232 External capacitor (voltage doubler) is connected to this lead. Not needed if both ports in RS-485 Mode.
C1-
RS-232 External capacitor (voltage doubler) is connected to this lead. Not needed if both ports in RS-485 Mode.
C2+
RS-232 External capacitor (voltage inverter) is connected to this lead. Not needed if both ports in RS-485 Mode.
C2-
RS-232 External capacitor (voltage inverter) is connected to this lead. Not needed if both ports in RS-485 Mode.
V+
RS-232 Internally generated positive RS-232 transmitter supply (+5.5V). C3 not needed if both ports in RS-485 Mode.
V-
RS-232 Internally generated negative RS-232 transmitter supply (-5.5V). C4 not needed if both ports in RS-485 Mode.
ISL81334, ISL41334
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