ISL41334IRZ-T7A Intersil, ISL41334IRZ-T7A Datasheet - Page 13

• 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

Test Circuits and Waveforms
Typical Application
RS-232 to RS-485 Converter
The ISL81334, ISL41334 are ideal for implementing a single
IC 2-wire (Tx Data, Rx Data) protocol converter, because
each port can be programmed for a different protocol.
Figure 8 illustrates the simple connections to create a single
transceiver RS-232 to RS-485 converter. Depending on the
RS-232 data rate, using an RS-422 bus as an RS-232
“extension cord” can extend the transmission distance up to
4000’ (1220m). A similar circuit on the other end of the cable
completes the conversion to/from RS-232.
Detailed Description
Each of the two ISL81334, ISL41334 ports supports dual
protocols: RS-485/422, and RS-232. RS-485 and RS-422 are
differential (balanced) data transmission standards for use in
high speed (up to 20Mbps) networks, or long haul and noisy
environments. The differential signaling, coupled with RS-485’s
requirement for extended common mode range (CMR) of +12V
to -7V make these transceivers extremely tolerant of ground
potential differences, as well as voltages induced in the cable
by external fields. Both of these effects are real concerns when
communicating over the RS-485, RS-422 maximum distance of
4000’ (1220m). It is important to note that the ISL81334,
ISL41334 don’t follow the RS-485 convention whereby the
inverting I/O is labeled “B/Z”, and the noninverting I/O is “A/Y”.
Thus, in the application diagrams below the 1334 A/Y (B/Z)
pins connect to the B/Z (A/Y) pins of the generic RS-485,
RS-422 ICs.
SIGNAL
GENERATOR
SIGNAL
GENERATOR
FIGURE 6A. TEST CIRCUIT
FIGURE 7A. TEST CIRCUIT
D
RXEN (QFN ONLY)
A, B
Y,Z
D
R
FIGURE 7. RS-232 RECEIVER PROPAGATION DELAY AND TRANSITION TIMES
FIGURE 6. RS-232 DRIVER PROPAGATION DELAY AND TRANSITION TIMES
13
R
A,
Y, Z
R
B
R
L
(Continued)
C
L
C
L
= 15pF
ISL81334, ISL41334
SKEW = |t
SKEW = |t
OUT (Y,Z)
RS-232 OUT
RS-485 OUT
FIGURE 8. SINGLE IC RS-232 TO RS-485 CONVERTER
R
D
A, B
RxD
A,
RS-485 IN
RS-232 IN
Y,Z
TxD
R
B
t
RPHL
0.1µF
0.1µF
DPHL
DPHL
+5V
V
NC
NC
FIGURE 6B. MEASUREMENT POINTS
FIGURE 7B. MEASUREMENT POINTS
C
C
CC
1
2
- t
NOTE: PINOUT FOR SOIC AND SSOP
- t
RPLH
+
+
+ 0.1µF
DPLH
28
27
11
10
13
12
1
2
4
5
6
7
8
9
t
1.5V
1.3V
RPHL
|
C1+
C1-
C2+
C2-
SEL1
B1
SEL2
A1
Y1
Z1
Y2
Z2
A2
B2
|
5kΩ
5kΩ
0V
0.8V
GND
V
CC
D
14
26
R
R
R
ON/OFF
D
D
R
R
D
D
R
DE2 18
D
V+
A1
B1
Y1
Z1
A2
Y2
V-
t
1.5V
1.7V
RPLH
3
15
24
19
25
22
23
20
17
NC
+ C
+
0V
0.1µF
C
0.1µF
V
2.4V
V
3
4
CC
CC
t
November 21, 2007
DPLH
3V
0V
3V
0V
V
V
V
V
OH
OL
FN6202.3
O+
O-