ISL41334IRZ-T7A Intersil, ISL41334IRZ-T7A Datasheet - Page 14

• Manufacturer Part Number: ISL41334IRZ-T7A
• Description: IC TXRX RS232/485 DL 2PRT 40QFN
• Manufacturer: Intersil

Specifications of ISL41334IRZ-T7A

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

RS-422 is typically a point-to-point (one driver talking to one
receiver on a bus), or a point-to-multipoint (multidrop)
standard that allows only one driver and up to 10 receivers
on each bus. Because of the one driver per bus limitation,
RS-422 networks use a two bus, full duplex structure for
bidirectional communication, and the Rx inputs and Tx
outputs (no tri-state required) connect to different busses, as
shown in Figure 10.
Conversely, RS-485 is a true multipoint standard, which
allows up to 32 devices (any combination of drivers- must be
tri-statable - and receivers) on each bus. Now bidirectional
communication takes place on a single bus, so the Rx inputs
and Tx outputs of a port connect to the same bus lines, as
shown in Figure 9. Each port set to RS-485 /422 mode
includes one Rx and one Tx.
RS-232 is a point-to-point, singled ended (signal voltages
referenced to GND) communication protocol targeting fairly
short (<150’, 46m) and low data rate (<1Mbps) applications.
Each port contains two transceivers (2 Tx and 2 Rx) in
RS-232 mode.
ISL81334, ISL41334 (MASTER)
Tx/Rx
ISL81334, ISL41334
OR NC
RXEN *
1kΩ
* QFN ONLY
DE
RA
DY
RA
DE
DY
D
D
R
R
+5V
GND
V
GND
V
+5V
B
A
Y
CC
Z
CC
A
B
Y
Z
14
+
+
R
R
0.1μF
0.1μF
T
T
+5V
0.1μF
FIGURE 9. TYPICAL HALF DUPLEX RS-485 NETWORK
GENERIC 1/2 DUPLEX 485 XCVR
ISL81334, ISL41334
V
FIGURE 10. TYPICAL RS-422 NETWORK
CC
RO
+5V
GENERIC 422 Rx (SLAVE)
0.1μF
R
RE
V
CC
B/Z
DE
RO
B
R
Protocol selection is handled via a logic pin (SELX) for each
port.
.
ISL81334, ISL41334 Advantages
These dual protocol ICs offer many parametric
improvements versus those offered on competing dual
protocol devices. Some of the major improvements are:
• 15kV Bus Pin ESD - Eases board level requirements
• 2.7V Diff V
• Full Failsafe RS-485 Rx - Eliminates bus biasing
• Selectable RS-485 Data Rate - Up to 20Mbps, or slewrate
• High RS-232 Data Rate - >460kbps
• Lower Tx and Rx Skews - Wider, consistent bit widths
• Lower I
• Flow-Thru Pinouts - Tx, Rx bus pins on one side/logic pins
• Smaller (SSOP and QFN) and Pb-free Packaging.
D
RE
A
DI
limited for low EMI and fewer termination issues
on the other, for easy routing to connector/UART
A/Y
GND
GND
CC
OUT
- Max I
GENERIC FULL DUPLEX 422 XCVR (SLAVE)
- Better Noise immunity and/or distance
CC
0.1μF
is 2x to 4x lower than competition
0.1μF
+
R
R
T
T
GENERIC 1/2 DUPLEX 485 XCVR
+
A
B
Z
Y
GND
+5V
V
A/Y
CC
B/Z
GND
V
+5V
CC
R
D
November 21, 2007
R
D
RO
DI
FN6202.3
RO
RE
DE
DI