isl3330 Intersil Corporation, isl3330 Datasheet - Page 18

• Manufacturer Part Number: isl3330
• Description: 3.3v, ?15kv Esd Protected, Dual Protocol Rs-232/rs-485 Transceivers
• Manufacturer: Intersil Corporation

slew limited edges permit longer unterminated networks, or
longer stubs off terminated busses, and help minimize EMI
and reflections. Nevertheless, for the best jitter performance
when driving long cables, the faster speed options may be
preferable, even at lower data rates. The faster output
transitions deliver less variability (jitter) when loaded with the
large capacitance associated with long cables. Of course,
faster transitions require more attention to ensuring short
stub lengths and quality terminations, so there are trade-offs
to be made. Assuming a jitter budget of 10%, it is preferable
to go with the slow speed option for data rates of 115kbps or
less to minimize fast edge effects. Likewise, the medium
speed option is a good choice for data rates between
115kbps and 460kbps. For higher data rates, or when the
absolute best jitter is required, use the high speed option.
Tx/Rx
FIGURE 12. USING ACTIVE LOW vs ACTIVE HIGH RX
ACTIVE LOW RX ENABLE
ACTIVE HIGH RX ENABLE
Tx/Rx
OR NC
1kΩ
ENABLE
RA
RXEN
RXEN *
* QFN ONLY
DEN
RXEN *
DY
RXEN
DEN
RA
DY
ISL3331
D
ISL3331
R
D
18
R
GND
+3.3V
V
CC
B
A
Y
Z
GND
+3.3V
V
B
A
Y
Z
CC
+
0.1µF
+
0.1µF
ISL3330, ISL3331
Evaluation Board
An evaluation board, part number ISL3331EVAL1Z, is
available to assist in assessing the dual protocol IC’s
performance. The evaluation board contains a QFN
packaged device, but because the same die is used in all
packages, the board is also useful for evaluating the
functionality of the other versions. The board’s design allows
for evaluation of all standard features, plus the QFN specific
features. Refer to the evaluation board application note for
details, and contact your sales representative for ordering
information.
May 20, 2008
FN6361.0