Intersil ISL41387EVAL1Z User Manual

®

ISL41387EVAL1Z User’s Manual

Application Note May 30, 2006

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 (VL)
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.

AN1248.1

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 subsequ ent revisions:

• Jumper labels “J-SELX” (not numbered) should be
“J-SELX (NC)” because they are not used for the
ISL41387

• Jumper label “J-RXEN2
“J-RXEN2

• 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
“J-ON/OFF

• 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 50Ω termination
resistor to GND when the jumper is in the “LOW” position.

(NC)” because it is not used for the ISL41387

(NC)” because it is not used for the ISL41387

” (not numbered) should be

” (not numbered) should be

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
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
RXEN1
(DZ/SLEW) (13) = VH; DZ1/DE1(DY) (14) = LOW;
RXBIAS-V
V

-VHIGH (17) = installed.

L

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.

) (7) =VH; (DEN)(8) =VH; SPB(9) =VH;

(10) =VH; (RXEN)(11) = VH; (ON) (12) =VH;

(15) = installed; VCC-VL(16) = installed;

CC

shorted to VCC. To achieve

L

1

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

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| Intersil (and design) is a registered trademark of Intersil Americas Inc.

All other trademarks mentioned are the property of their respective owners.

Copyright Intersil Americas Inc. 2006. All Rights Reserved

Application Note 1248

Functional Diagram (Default Configuration)

+5V

C

0.1μF
C

0.1μF

A1
B1

Y1
Z1

V

V

(16)

+

0.1μF

37

1

+

38
36

2

+

35

2
3

4
5

12

H

11 21

H

C1+

V

C1­C2+

C2-

DEN
485 / 232

34

CC

GND

V

L

R

D

15, 16

31

(17)

V+

V-

RXEN
RXEN

D

Y

SLEW

SPB

ON

VHIGH (VH )

1

C

+

0.1μF

19

C

0.1μF

+

30

R

A

29

R

B

20

V

17

V

28

27

V

14

V

V

3

4

H
H

H

H

H

VL - The logic supply voltage that sets the ISL41387’s Rx

output V
points; the “VCC-VL” (16) jumper shorts this jack to V
remove this jumper if supplying a voltage other than V

levels, and the logic and Tx input switching

OH

CC

CC

, so

.

Getting Started

Connect a 5V, 500mA minimum, power supply to the VCC
and GND banana jacks. It is recommended that an ammeter
be used between the supply and the board, so that I
be monitored. Ensure that the “RXBIAS-VCC” (15),
“VCC-VL” (16) and “VL-VHIGH” (17) jumpers are installed in
the upper right hand corner of the board.

External Loopback Via Jumpers

T o evaluate the Rx and Tx performance at the same time, an
external loopback can be implemented simply by installing
jumpers “A1/Y1_LB (5) and “B1/Z1_LB (6). In this
configuration, the Tx output lines connect to the
corresponding Rx input lines, so the data driven on the Tx
input(s) appears at the Rx output(s). In RS-485 mode, data
driven on DY loops back through A and B to R
mode, DY loops back to R

, and DZ loops back to RB.

A

For RS-485 mode, installing resistors R7 and R9 allows
evaluation of performance with the Tx driving a double
terminated load.

A

can

CC

. In RS-232

Supply Banana Jacks

There are eight banana jacks at the top of the board for
power supply connections, but only V
required connections. The function and use of each jack
(from left to right) is:

VLOAD - This is a load voltage driving the load resistors
connected to the Rx and Tx outputs (Tx resistors - R5 and
R6 - not populated); used mostly during output enable and
disable time characterizations.

GND - Common connection for any supplies used.
RXBIAS - A voltage that can be applied to any or all Rx

inputs via jumpers “J9” and “J10” (3 & 2); the “RXBIAS-VCC”

(15) jumper shorts this jack to V

supplying a voltage other than V

CC

CC

V+ - Used to monitor the positive charge pump voltage in
RS-232 mode.

V- - Used to monitor the negative charge pump voltage in
RS-232 mode.

VCC - The 5V supply connection.
VHIGH - Connects to all the “VH” positions on the jumpers to

define the high level voltage for logic and Tx inputs; the
“VL-VHIGH” (17) jumper shorts this jack to V
this jumper if supplying a voltage other than V

and GND are

CC

, so remove this jumper if

.

, so remove

L

.

L

Basic RS-485 DC Evaluation

General Observations

should be approximately 1.6mA.

I

CC

Measure V+ and V- at the banana jacks - V+ = VCC and
V- = GND, indicating that the charge pumps are off for low
power and low noise.

R

is high - due to the “full failsafe” Rx - while RB is always

A

tri-stated because it is unused in RS-485 mode.
Note that this board isn’t populated with 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.

Receiver Tests

The “full failsafe” nature of the Rx can be evaluated by
manipulating the “A1” (1) and “B1” (4) input jumpers. In the
default configuration, A1 and B1 float, but RA (measure at
the “RB1(RA)” test point to the right of jumper (1)) remains
high due to the failsafe “open” functionality. Installing
jumpers “A1” (1) and “B1” (4) ef fectively shorts the two inputs
together (i.e., V
the Rx is also failsafe “shorted”. The combination of failsafe
“open” and “shorted” yields a “full-failsafe” Rx.

To switch the Rx output state leave the “B1” (4) jumper
installed, remove the “A1” (1) jumper, and install the A1 Rx
bias jumper, “J10” (2). The “RXBIAS-VCC” (15) jumper now
drives the A1 input voltage to V

=0). RA still remains high, indicating that

ID

, which switches RA low.

CC

2

AN1248.1

May 30, 2006

Application Note 1248

Removing the “RXBIAS-VCC” (15) jumper , and connecting a
power supply between the “RXBIAS” banana jack and GND
now sets the Rx differential input voltage, via “A1”, and
varying this supply switches the Rx output state. For
example, with the RXBIAS supply = 0V (V

=0V) the

ID

output is high, and increasing RXBIAS to at least +200mV
(V

= -200mV) switches RA low.

ID

To disable the Rx output via the active high RXEN pin,
ensure that the “RXEN1

” (10) jumper is in the “VH” position,
and move jumper “(RXEN)” (11) to the “LOW” position. To
disable the Rx output via the active low RXEN

pin, ensure
that the “(RXEN)” jumper is in the “LOW” position, and move
jumper “RXEN1

” to the “VH” position.

Return the “RXEN1” and “(RXEN)” jumpers to the “VH”
position, remove the “RXBIAS” power supply and jumpers
“J10” and “B1”, and reinstall the “RXBIAS-VCC” jumper.

Driver Tests

Tx DC output levels are independent of Tx speed setting. In
the default configuration, the driver input, DY, is low, so the
Tx noninverting output, Z1, is low, while the inverting output,
Y1, is high. To switch the output states, simply move the
“DZ1/DE1 (DY) (14) jumper to the “VH” position. In either
state, note the exceptionally large differential voltage (V
of ≈3.5V. To evaluate the double terminated V

OD

OD

(≈3.3V),
install resistors R7 and R9, and configure the board for
“external loopback”, as described previously (i.e., install
jumpers (5) and (6)).

To disable the Tx output via the active high DEN pin, move
the “(DEN)” (8) jumper from the “VH” to the “LOW” position.

When finished, return the “DZ1/DE1 (DY)” and “(DEN)”
jumpers to the “LOW” and “VH” positions respectively, and
remove the “external loopback” jumpers.

Internal Loopback

To configure the ISL41387 for internal loopback mode,
simply move the “(ON)” (12) jumper to the “LOW” position,
while ensuring that the “(DEN)” (8) and “(RXEN)” (11)
jumpers are set to “VH”. Note that I

increases by ≈1.4mA,

CC

due to the enabling of the loopback receivers. RA is now low
due to the Tx outputs internally driving the Rx. You can
repeat the previous Rx switching tests to confirm that the
external Rx input pins now have no affect on RA.

The internal loopback receivers are not RS-485/422
compliant, so internal loopback can’t be used to create a
half duplex transceiver.

Low Power SHDN

With the “(ON)” (12) jumper still in the “LOW” position, move
the “(DEN)” (8) and “(RXEN)” (11) jumpers to the “LOW”
position, while ensuring that the “RXEN1

” (10) jumper is set
to “VH”. This setting places the ISL41387 into shutdown
(SHDN), which disables the Tx and Rx outputs, and places

the IC in its lowest power mode. Note that I

drops to less

CC

than 5µA.
Return jumpers “(ON)”, “(DEN)”, and “(RXEN)” to the “VH”

position.

Basic RS-485 AC Evaluation

Remember that there aren’t any differential term resistors,
so if they are desired they must be added at positions R7 ­for the Tx - and R9 for the Rx.

Receiver Tests

Before starting, ensure that the jumpers are back in the
default positions. Note that the RS-485 Rx operates at high
speed, regardless of the Tx speed selection.

Add jumper “B1” (4) to connect that input to GND, and add
jumper “A1” (1) to engage the 50Ω term. Connect a
generator to the “A1” BNC, and set it for a -1.5V to +1.5V
swing. Monitoring test points “TP6” (input), and “RB1 (RA)”
(output) with a scope allows the Rx prop delays and skews
to be measured. If desired, you can load the Rx output with a
1kΩ resistor by adding jumper “J6” (not numbered), located
below test point “RB1 (RA)”. This resistor terminates to the
“VLOAD” banana jack (upper left hand corner), allowing the

)

resistor to be terminated to GND by shorting “VLOAD” to
GND, or terminated to any voltage by connecting “VLOAD”
to an external supply.

You can also measure the Rx enable/disable time to/from a
low output state via the active high RXEN pin. From the
previous jumper configuration, leave the “B1” and “J6”
jumpers installed, remove the “A1” jumper, and install the A1
Rx bias jumper, “J10” (2). Connect the “VLOAD” jack to V

CC

switch the “(RXEN)” (11) jumper to the low position to
engage the 50Ω term, set the generator to swing from 0V to
3V, and move the generator to the “NC (RXEN)” BNC.
Monitoring test points “TP12” (input), and “RB1 (RA)”
(output) with a scope allows the Rx enable and disable times
to be measured. To evaluate the Rx enable/disable time
to/from a high output state, simply remove “J10”, and
connect “VLOAD” to GND.

To evaluate the Rx enable/disable times using the active low
RXEN

pin, repeat the previous test but leave the “(RXEN)”

jumper in the “LOW” position, move the “RXEN1

” (10)
jumper to the “LOW” position to connect the 50Ω term, and
connect the generator to the “RXEN1

” BNC.

Tx Speed Selection

Before performing any Tx switching tests, ensur e th at the
jumpers are in their default positions, and then configure the
“DZ/(SLEW)” (13) and “SPB” (9) jumpers for the desired Tx
speed setting. Table 1 details the jumper settings for each of
the speed options.

,

3

AN1248.1

May 30, 2006