1
®
AN1248.1
ISL41387EVAL1Z User’s Manual
Description
The ISL41387 evaluation board is RoHS compliant, and
provides a quick and easy method for evaluating this Dual
Protocol IC. The eval board also accommodates the
ISL41334; see the “ISL41334EVAL1Z User’s Manual” for
details.
This board was designed to allow the user to evaluate all the
features available on the ISL81387 and ISL41387 products.
The ISL41387 is the full featured version (see “Features”
below), where the QFN package’s increased pin count gives
the user access to functionality not available on the pin
limited ISL81387. The same die is used in both products, so
other than minor package effects, evaluating the QFN
packaged ISL41387 is a reasonable substitute for evaluating
the ISL81387.
By changing jumper positions the user can quickly set the
board to evaluate any of the ISL41387’s many modes and
features, and the input states can also be set via jumpers.
Refer to the data sheet for complete details regarding the
functions and features of this device. These dual protocol
ICs feature many modes, so studying the device’s truth-table
along with its operating circuits and detailed description is
the best way to gain an understanding of how the part works.
Features
• QFN Version Demonstrates All Enhanced Features:
Logic Supply Pin (V
L
)
Three RS-485 Speed Options - 115kbps/460kbps/20Mbps
Active Low RS-485 Rx Enable for Simple Direction Control
• Quick Configuration Using Jumpers
• State of All Inputs Can be Set by Jumper Positions
• No Bus Termination Resistors; Allows RS-232 or RS-485
Evaluation
• Simple Operation Requires Only One, 5V, Power Supply
Important Notes
To facilitate locating jumpers on this board, Figure 3 is a
jumper locator and, in this Application Note, the
(#)
following
a jumper mention corresponds to the red jumper number on
the locator. See the “Jumper Definitions” section for a
description of the function of each jumper.
The base board is used to evaluate both the ISL41334
(2 port) and ISL41387 (1 port) products, so the jumper and
connector names reflect the functionality of both products.
Due to space limitations some jumper labels are
abbreviated, but the corresponding BNC connector has the
full label.
In most cases, a name that applies to both products contains
no parenthesis (e.g., “B1”), a name that applies to only the
ISL41334 is followed by “(NC)” (e.g., “B2 (NC)”), and a name
that applies to only the ISL41387 is preceded by “NC” and/or
has the name in parenthesis (e.g., “NC (DEN)” or “(DEN)”).
Note that on “Rev. A” of these boards the following minor errors
have been noted, and are corrected on subsequent revisions:
• Jumper labels “J-SELX”
(not numbered)
should be
“J-SELX (NC)” because they are not used for the
ISL41387
• Jumper label “J-RXEN2”
(not numbered)
should be
“J-RXEN2 (NC)” because it is not used for the ISL41387
• Jumper label “J-RXEN”
(11)
should be “J-(RXEN)”
because it is only used for the ISL41387
• Jumper label “J-DE2”
(not numbered)
should be “J-DE2
(NC)” because it is not used for the ISL41387
• Jumper label “J-DY2”
(not numbered)
should be “J-DY2
(NC)” because it is not used for the ISL41387
• Jumper label “J-ON/OFF”
(not numbered)
should be
“J-ON/OFF (NC)” because it is not used for the ISL41387
• Jumper label “J-(SLEW)”
(13)
should be “J-DY1 (SLEW)”
• Jumper label “J-DE1”
(14)
should be “J-DZ1/DE1 (DY)”.
It is important to note that the ISLX1387 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, the 1387 A/Y
(B/Z) pins connect to the B/Z (A/Y) pins of generic
RS-485/422 ICs.
Input signals that are likely to be driven by a generator
connect to a BNC connector, and there is a 50
Ω
termination
resistor to GND when the jumper is in the “LOW” position.
Default Configuration
As delivered (see “Functional Diagram”), the board is
configured for powered-up (not SHDN) RS-485 mode, driver
enabled, via DEN, and set for high speed (20Mbps)
operation, driver input (DY) low, Rx enabled via the RXEN
line, Rx inputs floating, and V
L
shorted to V
CC
. To achieve
this configuration, the jumpers are installed as follows
(unlisted jumpers are not installed, and
(#)
indicates the
jumper number on the Figure 3 jumper locator):
A2 (485/232)
(7)
= VH; (DEN)
(8)
= VH; SPB
(9)
= VH;
RXEN1
(10)
= VH; (RXEN)
(11)
= VH; (ON)
(12)
= VH;
(DZ/SLEW)
(13)
= VH; DZ1/DE1(DY)
(14)
= LOW;
RXBIAS-V
CC
(15)
= installed; V
CC
-V
L
(16)
= installed;
V
L
-VHIGH
(17)
= installed.
Note that there are no differential termination resistors on
either the Rx inputs nor the Tx outputs. If these resistors are
desired, they can be added at positions R9 and R7,
respectively.
Application Note
May 30, 2006
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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