intersil ISL81387, ISL41387 DATA SHEET

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ISL81387, ISL41387

Data Sheet December 20, 2005

±15kV ESD Protected, Dual Protocol

(RS-232/RS-485) Transceivers

These devices are BiCMOS interface ICs that are user
configured as either a single RS-422/485 differential
transceiver, or as a dual (2 Tx, 2 Rx) RS-232 transceiver.

In RS-232 mode, the on-board charge pump generates
RS-232 compliant ±5V Tx output levels, from a supply as low
as 4.5V. Four small 0.1µF capacitors are required for the
charge pump. The transceivers are RS-232 compliant, with
the Rx inputs handling up to ±25V, and the Tx outputs
handling ±12V.

In RS-485 mode, the transceivers support both the RS-485
and RS-422 differential communication standards. The
RS-485 receiver features "full failsafe" operation, so the Rx
output remains in a high state if the inputs are open or
shorted together. The RS-485 transmitter supports up to
three data rates, two of which are slew rate limited for
problem free communications. The charge pump disables in
RS-485 mode, thereby saving power, minimizing noise, and
eliminating the charge pump capacitors.

Both RS-232/485 modes feature loopback and shutdown
functions. The loopback mode internally connects the Tx
outputs to the corresponding Rx input, which facilitates the
implementation of board level self test functions. The outputs
remain connected to the loads during loopback, so
connection problems (e.g., shorted connectors or cables)
can be detected. The shutdown mode disables the Tx and
Rx outputs, disables the charge pump if in RS-232 mode,
and places the IC in a low current (20µA) mode.

The ISL41387 is a QFN packaged device that offers
additional functionality, including a lower speed and edge
rate option (115kbps) for EMI sensitive designs, or to allow
longer bus lengths. It also features a logic supply voltage pin
(V

) that sets the VOH level of logic outputs, and the

L

switching points of logic inputs, to be compatible with
another supply voltage in mixed voltage systems. The QFN's
choice of active high or low Rx enable pins increases design
flexibility, allowing Tx/Rx direction control via a single signal
by connecting DEN and RXEN

together.

FN6201.1

Features

• User Selectable RS-232 or RS-485/422 Interface Port
(Two RS-232 Transceivers or One RS-485/422
Transceiver)

• ±15kV (HBM) ESD Protected Bus Pins (RS-232 or
RS-485)

• Flow-Through Pinouts Simplify Board Layouts

• Pb-Free Plus Anneal Available (RoHS Compliant)

• Large (2.7V) Differential V

for Improved Noise

OUT

Immunity in RS-485/422 Networks

• Full Failsafe (Open/Short) Rx in RS-485/422 Mode

• Loopback Mode Facilitates Board Self Test Functions

• User Selectable RS-485 Data Rates . . . . . . . . . . 20Mbps

- Slew Rate Limited. . . . . . . . . . . . . . . . . . . . . . . 460kbps

- Slew Rate Limited (ISL41387 Only) . . . . . . . . . 115kbps

• Fast RS-232 Data Rate . . . . . . . . . . . . . . . Up to 650kbps

• Low Current Shutdown Mode. . . . . . . . . . . . . . . . . . .35µA

• QFN Package Saves Board Space (ISL41387 Only)

• Logic Supply Pin (V

) Eases Operation in Mixed Supply

L

Systems (ISL41387 Only)

Applications

• Gaming Applications (e.g., Slot machines)

• Single Board Computers

• Factory Automation

• Security Networks

• Industrial/Process Control Networks

• Level Translators (e.g., RS-232 to RS-422)

• Point of Sale Equipment

For a dual port version of these devices, please see the
ISL81334/ISL41334 data sheet.

TABLE 1. SUMMARY OF FEATURES

PART

NUMBER

ISL81387 1 20 Ld SOIC, 20 Ld SSOP 20M, 460k 650 NO H YES

ISL41387 1 40 Ld QFN (6 x 6mm) 20M, 460k, 115k 650 YES BOTH YES

NO. OF
PORTS

PACKAGE OPTIONS

1

RS-485 DATA

RATE (bps)

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

1-888-INTERSIL or 1-888-468-3774

RS-232 DATA

RATE (kbps)

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

V

PIN?

L

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

Copyright © Intersil Americas Inc. 2005. All Rights Reserved.

ACTIVE H or L

Rx ENABLE?

LOW POWER
SHUTDOWN?

ISL81387, ISL41387

Ordering Information

PART NUMBER (NOTE) PART MARKING TEMP. RANGE (°C) PACKAGE (Pb-Free) PKG. DWG. #

ISL81387IAZ 81387IAZ -40 to 85 20 Ld SSOP M20.209

ISL81387IAZ-T 81387IAZ -40 to 85 20 Ld SSOP Tape and Reel M20.209

ISL81387IBZ ISL81387IBZ -40 to 85 20 Ld SOIC M20.3

ISL81387IBZ-T ISL81387IBZ -40 to 85 20 Ld SOIC Tape and Reel M20.3

ISL41387IRZ 41387IRZ -40 to 85 40 Ld QFN L40.6x6

ISL41387IRZ-T 41387IRZ -40 to 85 40 Ld QFN Tape and Reel L40.6x6

NOTE: Intersil Pb-free plus anneal products employ special Pb-free material sets; molding compounds/die attach materials and 100% matte tin plate
termination finish, which are RoHS compliant and compatible with both SnPb and Pb-free soldering operations. Intersil Pb-free products are MSL
classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.

Pinouts

ISL81387 (SOIC, SSOP)

TOP VIEW

20

C1+

C1­V+

485/232

DEN

GND

1
2
3

A

4

B

5

Y

6

Z

7
8
9

10

C2+
C2-

19

V

18

CC

R

17

A

R

16

B

D

15

Y

D

/SLEW

14

Z

ON

13
12

RXEN

11

V-

V+

NC

NC

NC

NC

NC

ISL41387 (QFN)

TOP VIEW

NC

40

1

2

A

3

B

4

Y

5

Z

6

7

8

9

10

11 12 13 14 15 16 17 18 19 20

485/232

C1-

C1+

C2+

39 38 37 36 35 34 33 32 31

NC

DEN

SPB

GND

C2-NCV

GND

CC

RXEN

NC

NC

NC

V-

L

V

RXEN

30

29

28

27

26

25

24

23

22

21

R

A

R

B

D

Y

DZ/SLEW

NC

NC

NC

NC

NC

ON

2

FN6201.1

December 20, 2005

ISL81387, ISL41387

TABLE 2. ISL81387 FUNCTION TABLE

INPUTS

ON RXEN DEN SLEW R

RECEIVER

OUTPUTS DRIVER OUTPUTS

A

R

B

YZ

DRIVER

SPEED

(Mbps)

0 1 0 0 N.A. High-Z High-Z High-Z High-Z - ON OFF RS-232

0 1 0 1 N.A. High-Z High-Z ON ON 0.46 ON OFF RS-232

0 1 1 0 N.A. ON ON High-Z High-Z - ON OFF RS-232

0 1 1 1 N.A. ON ON ON ON 0.46 ON OFF RS-232

0 0 0 1 N.A. High-Z High-Z ON High-Z 0.46 ON OFF RS-232

0 0 1 0 N.A. High-Z ON ON High-Z 0.46 ON OFF RS-232

0 0 1 1 N.A. ON ON ON ON 0.46 ON ON RS-232

X 0 0 0 X High-Z High-Z High-Z High-Z - OFF OFF Shutdown

1 1 0 0 X High-Z High-Z High-Z High-Z - OFF OFF RS-485

1 X 0 1 1/0 High-Z High-Z ON ON 20/0.46 OFF OFF RS-485

1 X 1 0 X ON High-Z High-Z High-Z - OFF OFF RS-485

1 1 1 1 1/0 ON High-Z ON ON 20/0.46 OFF OFF RS-485

1 0 1 1 1/0 ON High-Z ON ON 20/0.46 OFF ON RS-485

NOTES:

1. Charge pumps are on if in RS-232 mode and ON or DEN or RXEN are high.

2. Loopback is enabled when ON = 0, and DEN = RXEN = 1.

CHARGE

PUMPS

(NOTE 1)

LOOPBACK

(NOTE 2) MODE485/232

ISL81387 Truth Tables

RS-232 TRANSMITTING MODE

INPUTS (ON = 1) OUTPUTS

485/232

010011

010110

011001

011100

0 0 X X High-Z High-Z

485/232

010011

010110

011001

011100

0 1 Open Open 1 1

0 0 X X High-Z High-Z

DEN D

Y

D

Z

YZ

RS-232 RECEIVING MODE

INPUTS (ON = 1) OUTPUT

RXEN A B R

A

R

RS-485 TRANSMITTING MODE

INPUTS (ON = 1) OUTPUTS

DATA RATE

485/232

DEN DYSLEW Y Z

(Mbps)

110110 20

111101 20

110010 0.46

111001 0.46

1 0 X X High-Z High-Z -

RS-485 RECEIVING MODE

INPUTS (ON = 1) OUTPUT

B

485/232

RXEN B-A R

R

A

B

11 ≥ -40mV 1 High-Z

11 ≤ -200mV 0 High-Z

1 1 Open or Shorted together 1 High-Z

1 0 X High-Z High-Z

3

FN6201.1

December 20, 2005

ISL81387, ISL41387

TABLE 3. ISL41387 FUNCTION TABLE

RECEIVER

OUTPUTS

R

A

B

ON

INPUTS

RXEN

and/or

RXEN

DEN SLEW SPB R

0 1 1 and 0 0 N.A. N.A. High-Z High-Z High-Z High-Z - ON RS-232

0 1 1 and 0 1 N.A. N.A. High-Z High-Z ON ON 0.46 ON RS-232

0 1 0 or 1 0 N.A. N.A. ON ON High-Z High-Z - ON RS-232

0 1 0 or 1 1 N.A. N.A. ON ON ON ON 0.46 ON RS-232

0 0 1 and 0 1 N.A. N.A. High-Z High-Z ON High-Z 0.46 ON RS-232

0 0 0 or 1 0 N.A. N.A. High-Z ON ON High-Z 0.46 ON RS-232

0 0 0 or 1 1 N.A. N.A. ON ON ON ON 0.46 ON RS-232 (Note 4)

X 0 1 and 0 0 X X High-Z High-Z High-Z High-Z - OFF Shutdown

1 1 1 and 0 0 X X High-Z High-Z High-Z High-Z - OFF RS-485

1 X 1 and 0 1 0 1/0 High-Z High-Z ON ON 0.46/0.115 OFF RS-485

1 X 1 and 0 1 1 X High-Z High-Z ON ON 20 OFF RS-485

1 X 0 or 1 0 X X ON High-Z High-Z High-Z - OFF RS-485

1 1 0 or 1 1 0 1/0 ON High-Z ON ON 0.46/0.115 OFF RS-485

1 1 0 or 1 1 1 X ON High-Z ON ON 20 OFF RS-485

1 0 0 or 1 1 0 1/0 ON High-Z ON ON 0.46/0.115 OFF RS-485 (Note 4)

1 0 0 or 1 1 1 X ON High-Z ON ON 20 OFF RS-485 (Note 4)

NOTES:

3. Charge pumps are on if in RS-232 mode and ON or DEN or RXEN is high, or RXEN

4. Loopback is enabled when ON = 0, and DEN = 1, and (RXEN = 1 or RXEN

= 0).

DRIVER

OUTPUTS

YZ

is low.

DRIVER

DATA
RATE

(Mbps)

CHARGE

PUMPS

(NOTE 3) MODE 485/232

ISL41387 Truth Tables

RS-232 TRANSMITTING MODE

INPUTS (ON=1) OUTPUTS

485/232

DEN D

Y

0 1 0011

0 1 0110

0 1 1001

0 1 1100

0 0 X X High-Z High-Z

RS-232 RECEIVING MODE

INPUTS (ON=1) OUTPUT

485/232

RXEN and/or A B R

00 or 10011

00 or 10110

00 or 11001

00 or 11100

0 0 or 1 Open Open 1 1

0 1 and 0 X X High-Z High-Z

D

Z

YZ

R

A

B

RS-485 TRANSMITTING MODE

INPUTS (ON=1) OUTPUTS DATA

485/232

DEN SLEW SPB D

YZMbps

Y

1 1 0 0 0/1 1/0 0/1 0.115

1 1 0 1 0/1 1/0 0/1 0.460

1 1 1 X 0/1 1/0 0/1 20

1 0 X X X High-Z High-Z -

RS-485 RECEIVING MODE

INPUTS (ON=1) OUTPUT

485/232

RXEN and/or B-A R

A

10 or 1 ≥ -40mV 1 High-Z

10 or 1≤ -200mV 0 High-Z

1 0 or 1 Open or Shorted

1 High-Z

together

1 1 and 0 X High-Z High-Z

R

B

4

FN6201.1

December 20, 2005

ISL81387, ISL41387

Pin Descriptions

PIN MODE FUNCTION

485/232

DEN BOTH Driver output enable. The driver outputs, Y and Z, are enabled by bringing DEN high. They are high impedance when DEN

GND BOTH Ground connection.

NC BOTH No Connection.

ON BOTH In RS-232 mode only, ON high enables the charge pumps. ON low, with DEN and RXEN low (and RXEN

RXEN BOTH Receiver output enable. Rx is enabled when RXEN is high; Rx is high impedance when RXEN is low and, if using the QFN

RXEN

V

D

D

SLEW RS-485 Slew rate control. With the SLEW pin high, the drivers run at the maximum slew rate (20Mbps). With the SLEW pin low, the

SPB RS-485 Speed control. Works in conjunction with the SLEW pin to select the 20Mbps, 460kbps or 115kbps RS-485 data rate.

R

R

C1+ RS-232 External capacitor (voltage doubler) is connected to this lead. Not needed in RS-485 Mode.

C1- RS-232 External capacitor (voltage doubler) is connected to this lead. Not needed in RS-485 Mode.

C2+ RS-232 External capacitor (voltage inverter) is connected to this lead. Not needed in RS-485 Mode.

C2- RS-232 External capacitor (voltage inverter) is connected to this lead. Not needed in RS-485 Mode.

V+ RS-232 Internally generated positive RS-232 transmitter supply (+5.5V). C3 not needed in RS-485 Mode.

BOTH Interface Mode Select input. High for RS-485 Mode and low for RS-232 Mode.

is low.

high if QFN), turns
off the charge pumps (in RS-232 mode), and in either mode places the device in low power shutdown. In both modes, when
ON is low, and DEN is high, and RXEN is high or RXEN

package, RXEN

is high. When using the QFN and the active high Rx enable function, RXEN should be high or floating.

is low, loopback is enabled.

BOTH Active low receiver output enable. Rx is enabled when RXEN is low; Rx is high impedance when RXEN is high and RXEN

is low. (i.e., to use active low Rx enable function, tie RXEN to GND). For single signal Tx/Rx direction control, connect RXEN
to DEN. Internally pulled high. (QFN only)

BOTH System power supply input (5V).

CC

V

BOTH Logic-Level Supply. All TTL/CMOS inputs and outputs are powered by this supply. (QFN only)

L

A RS-232 Receiver input with ±15kV ESD protection. A low on A forces R

high; A high on A forces RA low.

A

RS-485 Inverting receiver input with ±15kV ESD protection.

B RS-232 Receiver input with ±15kV ESD protection. A low on B forces R

high; A high on B forces RB low.

B

RS-485 Noninverting receiver input with ±15kV ESD protection.

RS-232 Driver input. A low on DY forces output Y high. Similarly, a high on DY forces output Y low.

Y

RS-485 Driver input. A low on D

RS-232 Driver input. A low on DZ forces output Z high. Similarly, a high on DZ forces output Z low.

Z

forces output Y high and output Z low. Similarly, a high on DY forces output Y low and output Z high.

Y

drivers run at a reduced slew rate (460kbps). On the QFN version, works in conjunction with SPB to select one of three
RS-485 data rates. Internally pulled high in RS-485 mode.

Internally pulled high. (QFN only)

RS-232 Receiver output.

A

RS-485 Receiver output: If B > A by at least -40mV, R

is high; If B < A by -200mV or more, RA is low; RA = High if A and B are

A

unconnected (floating) or shorted together (i.e., full fail-safe).

RS-232 Receiver output.

B

RS-485 Not used. Output is high impedance, and unaffected by RXEN

and RXEN.

Y RS-232 Driver output with ±15kV ESD protection.

RS-485 Inverting driver output with ±15kV ESD protection.

Z RS-232 Driver output with ±15kV ESD protection.

RS-485 Noninverting driver output with ±15kV ESD protection.

V- RS-232 Internally generated negative RS-232 transmitter supply (-5.5V). C4 not needed in RS-485 Mode.

5

FN6201.1

December 20, 2005

/

Typical Operating Circuit

RS-232 MODE WITHOUT LOOPBACK

ISL81387, ISL41387

RS-232 MODE WITH LOOPBACK

+5V

C

0.1µF

C

0.1µF

V

CC

+

0.1µF

1

1

2

A

B

Y

Z

C1+

+

2

C1-

20

C2+

+

19

C2-

4

5kΩ

516

5kΩ

6

7

9

DEN

813

485/232

18

V

CC

R

R

D

D

V+

RXEN

ON

V-

3

C

3

+

0.1µF

11

C

4

0.1µF

+

17

R

A

R

B

15

D

Y

14

D

Z

12

V

CC

V

CC

GND

10

NOTE: PINOUT FOR SOIC AND SSOP

+5V

C

0.1µF

C

0.1µF

V

CC

+

A1

0.1µF

1

1

2

C1+

+

2

C1-

20

C2+

+

19

C2-

4

18

V

CC

R

5kΩ

5

B1

Y

Z

6

7

5kΩ

R

LB
Rx

D

D

9

DEN

8

485/232

GND

10

NOTE: PINOUT FOR SOIC AND SSOP

RXEN

ON

V+

V-

3

C

3

+

0.1µF

11

C

4

0.1µF

+

17

R

A

16

R

B

15

D

Y

14

D

Z

12

V

CC

13

RS-485 MODE WITHOUT LOOPBACK

+5V

+

C

0.1µF

C

0.1µF

V

CC

V

CC

0.1µF

1

1

2

A

B

Y

Z

C1+

+

2

C1-

20

C2+

+

19

C2-

4

5

6

7

9

DEN

813

485/232

V

CC

GND

18

R

D

RXEN

10

V+

V-

ON

RS-485 MODE WITH LOOPBACK

+5V

+

0.1µF

1

3

C

3

+

0.1µF

11

C

4

0.1µF

+

17

R

A

16

R

B

15

D

Y

C

0.1µF

C

0.1µF

1

2

Y

Z

14

SLEW

12

V

CC

V

CC

V

CC

V

CC

C1+

+

2

C1-

20

C2+

+

19

C2-

4

A

5

B

6

7

9

DEN

8

485/232

V

CC

R

LB
Rx

GND

18

3

C

3

V+

V-

D

RXEN

ON

+

0.1µF

11

C

4

0.1µF

+

17

R

A

16

R

B

15

D

Y

14

SLEW

12

V

CC

13

10

NOTE: PINOUT FOR SOIC AND SSOP

6

NOTE: PINOUT FOR SOIC AND SSOP

FN6201.1

December 20, 2005

ISL81387, ISL41387

Absolute Maximum Ratings (T

VCC to Ground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7V

V

(QFN Only) . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to VCC + 0.5V

L

Input Voltages

All Except A,B (non-QFN Package) . . . . . . -0.5V to (V

All Except A,B (QFN Package). . . . . . . . . . . -0.5V to (V

Input/Output Voltages

A, B (Any Mode) . . . . . . . . . . . . . . . . . . . . . . . . . . . . -25V to +25V

Y, Z (Any Mode, Note 5) . . . . . . . . . . . . . . . . . . . -12.5V to +12.5V

R

, RB (non-QFN Package). . . . . . . . . . . . -0.5V to (VCC + 0.5V)

A

R

, RB (QFN Package) . . . . . . . . . . . . . . . . -0.5V to (VL + 0.5V)

A

Output Short Circuit Duration

Y, Z , R

, RB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Indefinite

A

= 25°C) Thermal Information

A

Thermal Resistance (Typical, Note 6)

20 Ld SOIC Package . . . . . . . . . . . . . . . . . . . . . . . . 65

20 Ld SSOP Package . . . . . . . . . . . . . . . . . . . . . . . 60

CC

L

+ 0.5V)
+ 0.5V)

40 Ld QFN Package. . . . . . . . . . . . . . . . . . . . . . . . . 32

Maximum Junction Temperature (Plastic Package) . . . . . . . 150°C

Maximum Storage Temperature Range. . . . . . . . . . -65°C to 150°C

Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . 300°C

(SOIC and SSOP - Lead Tips Only)

Operating Conditions

Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . -40°C to 85°C

θ

JA

(°C/W)

ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . See Specification Table

CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the
device at these or any other conditions above those indicated in the operational sections of this specification is not implied.

NOTES:

5. One output at a time, I

6. QFN θ

θ

is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features.

JA

for other packages is measured with the component mounted on a high effective thermal conductivity test board in free air. See Tec h B r i e f

JA

≤ 100mA for ≤ 10 mins.

OUT

TB379 and Tech Brief TB389 for details.

Electrical Specifications Test Conditions: V

Typicals are at V

= 4.5V to 5.5V, C1 - C4 = 0.1µF, VL = VCC (for QFN only), Unless Otherwise Specified.

CC

= 5V, TA = 25°C (Note 7)

CC

TEMP

PARAMETER SYMBOL TEST CONDITIONS

DC CHARACTERISTICS - RS-485 DRIVER (485/232

Driver Differential V

Driver Differential V

(no load) V

OUT

(with load) V

OUT

OD1

OD2

R = 50Ω (RS-422) (Figure 1) Full 2.5 3.1 - V

= VCC)

(°C) MIN TYP MAX UNITS

Full - - V

CC

V

R = 27Ω (RS-485) (Figure 1) Full 2.2 2.7 5 V

Change in Magnitude of Driver
Differential V
Complementary Output States

Driver Common-Mode V

OUT

for

OUT

Change in Magnitude of Driver
Common-Mode V

OUT

for

V

∆V

V

∆V

OD3

RD = 60Ω, R = 375Ω, VCM = -7V to 12V (Figure 1) Full 2 2.7 5 V

R = 27Ω or 50Ω (Figure 1) Full - 0.01 0.2 V

OD

R = 27Ω or 50Ω (Figure 1) (Note 11) Full - - 3.1 V

OC

R = 27Ω or 50Ω (Figure 1) (Note 11) Full - 0.01 0.2 V

OC

Complementary Output States

Driver Short-Circuit Current,
V

= High or Low

OUT

Driver Three-State Output Leakage
Current (Y, Z)

I

OS

I

OZ

DC CHARACTERISTICS - RS-232 DRIVER (485/232

Driver Output Voltage Swing V
Driver Output Short-Circuit Current I

OS

-7V ≤ (VY or VZ) ≤ 12V (Note 9) Full 35 - 250 mA

Outputs Disabled,
V

= 0V or 5.5V

CC

= 12V Full - - 150 µA

V

OUT

= -7V Full -150 - - µA

V

OUT

= 0V)

All T

O

V

OUT

Loaded with 3kΩ to Ground Full ±5.0 +6/-7 - V

OUTS

= 0V Full -60 25/-35 60 mA

DC CHARACTERISTICS - LOGIC PINS (i.e., DRIVER AND CONTROL INPUT PINS)

Input High Voltage V

V

V

VL = VCC if QFN Full 2 1.6 - V

IH1

VL = 3.3V (QFN Only) Full 2 1.2 - V

IH2

VL = 2.5V (QFN Only) Full 1.5 1 - V

IH3

7

FN6201.1

December 20, 2005

ISL81387, ISL41387

Electrical Specifications Test Conditions: V

Typicals are at V

= 4.5V to 5.5V, C1 - C4 = 0.1µF, VL = VCC (for QFN only), Unless Otherwise Specified.

CC

= 5V, TA = 25°C (Note 7) (Continued)

CC

TEMP

PARAMETER SYMBOL TEST CONDITIONS

Input Low Voltage V

Input Current I

V

V

IN1

I

IN2

VL = VCC if QFN Full - 1.4 0.8 V

IL1

VL = 3.3V (QFN Only) Full - 1 0.7 V

IL2

VL = 2.5V (QFN Only) Full - 0.8 0.5 V

IL3

Except SLEW, RXEN (QFN), and SPB (QFN) Full -2 - 2 µA

SLEW (Note 12), RXEN (QFN), and SPB (QFN) Full -25 - 25 µA

DC CHARACTERISTICS - RS-485 RECEIVER INPUTS (485/232

Receiver Differential Threshold
Voltage

Receiver Input Hysteresis ∆V

Receiver Input Current (A, B) I

V

-7V ≤ VCM ≤ 12V, Full Failsafe Full -0.2 - -0.04 V

TH

VCM = 0V 25 - 35 - mV

TH

VCC = 0V or 4.5 to 5.5V VIN = 12V Full - - 0.8 mA

IN

= VCC)

(°C) MIN TYP MAX UNITS

VIN = -7V Full -0.64 - - mA

Receiver Input Resistance R

-7V ≤ VCM ≤ 12V, VCC = 0 (Note 10), or

IN

4.5V ≤ V

CC

≤ 5.5V

Full 15 - - kΩ

DC CHARACTERISTICS - RS-232 RECEIVER INPUTS (485/232 = GND)

Receiver Input Voltage Range V
Receiver Input Threshold V

Receiver Input Hysteresis ∆V
Receiver Input Resistance R

IN

IL

V

IH

TH

VIN = ±15V, VCC Powered Up (Note 10) Full 3 5 7 kΩ

IN

Full -25 - 25 V

Full - 1.4 0.8 V

Full 2.4 1.9 - V

25 - 0.5 - V

DC CHARACTERISTICS - RECEIVER OUTPUTS (485 OR 232 MODE)

Receiver Output High Voltage V

V

V

Receiver Output Low Voltage V

Receiver Short-Circuit Current I

Receiver Three-State Output
Current

OH1IO

OH2IO

OH3IO

OL

OSR

I

OZR

= -2mA (VL = VCC if QFN) Full 3.5 4.6 - V

= -650µA, VL = 3V, QFN Only Full 2.6 2.9 - V

= -500µA, VL = 2.5V, QFN Only Full 2 2.4 - V

IO = 3mA Full - 0.1 0.4 V

0V ≤ VO ≤ V

CC

Full 7 - 85 mA

Output Disabled, 0V ≤ VO ≤ VCC (or VL for QFN) Full - - ±10 µA

POWER SUPPLY CHARACTERISTICS

No-Load Supply Current, Note 8 I

Shutdown Supply Current I

CC232

I

CC485

SHDN232

I

SHDN485

485/232 = 0V, ON = V

485/232 = VCC, ON = V

CC

CC

ON = DEN = RXEN = 0V
(RXEN

= SPB = V

CC

if QFN)

ON = DEN = RXEN = SLEW = 0V
(RXEN

= VCC, SPB = 0V if QFN)

Full - 3.7 7 mA

Full - 1.6 5 mA

Full - 5 30 µA

Full - 35 60 µA

ESD CHARACTERISTICS

Bus Pins (A, B, Y, Z) Any Mode Human Body Model 25 - 15 - kV

All Other Pins Human Body Model 25 - 4 - kV

RS-232 DRIVER and RECEIVER SWITCHING CHARACTERISTICS (485/232

Driver Output Transition Region

Slew Rate

SR R

=3kΩ, Measured From 3V to

L

-3V or -3V to 3V

= 0V, ALL VERSIONS AND SPEEDS)

CL ≥ 15pF Full - 18 30 V/µs

C

≤ 2500pF Full 4 12 - V/µs

L

8

FN6201.1

December 20, 2005

ISL81387, ISL41387

Electrical Specifications Test Conditions: V

Typicals are at V

= 4.5V to 5.5V, C1 - C4 = 0.1µF, VL = VCC (for QFN only), Unless Otherwise Specified.

CC

= 5V, TA = 25°C (Note 7) (Continued)

CC

TEMP

PARAMETER SYMBOL TEST CONDITIONS

Driver Output Transition Time t

Driver Propagation Delay t

Driver Propagation Delay Skew t

Driver Enable Time t

Driver Disable Time t

Driver Enable Time from Shutdown t

DPHL

t

DPLH

DSKEWtDPHL

DEN

DDIS

DENSDVOUT

Driver Maximum Data Rate DR

Receiver Propagation Delay t

Receiver Propagation Delay Skew t

RPHL

t

RPLH

RSKEWtRPHL

Receiver Maximum Data Rate DR

, t

r

RL=3kΩ, CL = 2500pF, 10% - 90% Full 0.22 1.2 3.1 µs

f

RL=3kΩ, C

RL=5kΩ, Measured at V

= 1000pF (Figure 6) Full - 1 2 µs

L

- t

(Figure 6) Full - 240 400 ns

DPLH

= ±3V 25 - 500 - ns

OUT

= ±3.0V (Note 13) 25 - 20 - µs

RL=3kΩ, CL= 1000pF, One Transmitter

D

Switching

C

= 15pF (Figure 7) Full - 50 120 ns

L

- t

(Figure 7) Full - 10 40 ns

RPLH

CL= 15pF Full 0.46 2 - Mbps

R

(°C) MIN TYP MAX UNITS

Full - 1.2 2 µs

25 - 800 - ns

Full 460 650 - kbps

Full - 40 120 ns

RS-485 DRIVER SWITCHING CHARACTERISTICS (FAST DATA RATE (20Mbps), 485/232 = VCC, SLEW = VCC, ALL VERSIONS)

Driver Differential Input to Output
Delay

Driver Output Skew t

Driver Differential Rise or Fall Time tR, t

Driver Enable to Output Low t

Driver Enable to Output High t

Driver Disable from Output Low t

Driver Disable from Output High t

Driver Enable from Shutdown to
Output Low

Driver Enable from Shutdown to
Output High

Driver Maximum Data Rate f

RS-485 DRIVER SWITCHING CHARACTERISTICS (MEDIUM DATA RATE (460kbps), 485/232

t

, t

DLH

DHLRDIFF

SKEW

F

ZL

ZH

LZ

HZ

t

ZL(SHDN)RL

t

ZH(SHDN)RL

MAX

= 54Ω, CL = 100pF (Figure 2) Full 15 30 50 ns

R

= 54Ω, CL = 100pF (Figure 2) Full - 0.5 10 ns

DIFF

R

= 54Ω, CL = 100pF (Figure 2) Full 3 11 20 ns

DIFF

CL = 100pF, SW = VCC (Figure 3) Full - 27 60 ns

CL = 100pF, SW = GND (Figure 3) Full - 24 60 ns

CL = 15pF, SW = VCC (Figure 3) Full - 31 60 ns

CL = 15pF, SW = GND (Figure 3) Full - 24 60 ns

= 500Ω, CL = 100pF, SW = VCC (Figure 3)

Full - 65 250 ns

(Note 13)

= 500Ω, CL = 100pF, SW = GND (Figure 3)

Full - 152 250 ns

(Note 13)

R

= 54Ω, CL = 100pF (Figure 2) Full - 30 - Mbps

DIFF

= VCC, SLEW = SPB (QFN Only) = GND, ALL

VERSIONS)

Driver Differential Input to Output
Delay

Driver Output Skew t

Driver Differential Rise or Fall Time t

Driver Enable to Output Low t

Driver Enable to Output High t

Driver Disable from Output Low t

Driver Disable from Output High t

Driver Enable from Shutdown to
Output Low

Driver Enable from Shutdown to
Output High

Driver Maximum Data Rate f

t

, t

DLH

DHLRDIFF

SKEW

, t

R

F

ZL

ZH

LZ

HZ

t

ZL(SHDN)RL

t

ZH(SHDN)RL

MAX

= 54Ω, CL = 100pF (Figure 2) Full 200 490 1000 ns

R

= 54Ω, CL = 100pF (Figure 2) Full - 110 400 ns

DIFF

R

= 54Ω, CL = 100pF (Figure 2) Full 300 600 1100 ns

DIFF

CL = 100pF, SW = VCC (Figure 3) Full - 30 300 ns

CL = 100pF, SW = GND (Figure 3) Full - 128 300 ns

CL = 15pF, SW = VCC (Figure 3) Full - 31 60 ns

CL = 15pF, SW = GND (Figure 3) Full - 24 60 ns

= 500Ω, CL = 100pF, SW = VCC (Figure 3)

Full - 65 500 ns

(Note 13)

= 500Ω, CL = 100pF, SW = GND (Figure 3)

Full - 255 500 ns

(Note 13)

R

= 54Ω, CL = 100pF (Figure 2) Full - 2000 - kbps

DIFF

9

FN6201.1

December 20, 2005

ISL81387, ISL41387

Electrical Specifications Test Conditions: V

Typicals are at V

= 4.5V to 5.5V, C1 - C4 = 0.1µF, VL = VCC (for QFN only), Unless Otherwise Specified.

CC

= 5V, TA = 25°C (Note 7) (Continued)

CC

TEMP

PARAMETER SYMBOL TEST CONDITIONS

(°C) MIN TYP MAX UNITS

RS-485 DRIVER SWITCHING CHARACTERISTICS (SLOW DATA RATE (115kbps, QFN ONLY), 485/232 = VCC, SLEW = 0V, SPB = VCC)

Driver Differential Input to Output
Delay

Driver Output Skew t

Driver Differential Rise or Fall Time tR, t

Driver Enable to Output Low t

Driver Enable to Output High t

Driver Disable from Output Low t

Driver Disable from Output High t

Driver Enable from Shutdown to
Output Low

Driver Enable from Shutdown to

, t

t

DLH

DHLRDIFF

SKEW

F

ZL

ZH

LZ

HZ

t

ZL(SHDN)RL

t

ZH(SHDN)RL

Output High

Driver Maximum Data Rate f

MAX

RS-485 RECEIVER SWITCHING CHARACTERISTICS (485/232

Receiver Input to Output Delay t

Receiver Skew | t

PLH

- t

|t

PHL

Receiver Maximum Data Rate f

PLH

SKEW

, t

MAX

PHL

= 54Ω, CL = 100pF (Figure 2) Full 800 1500 2500 ns

R

= 54Ω, CL = 100pF (Figure 2) Full - 350 1250 ns

DIFF

R

= 54Ω, CL = 100pF (Figure 2) Full 1000 2000 3100 ns

DIFF

CL = 100pF, SW = VCC (Figure 3) Full - 32 600 ns

CL = 100pF, SW = GND (Figure 3) Full - 300 600 ns

CL = 15pF, SW = VCC (Figure 3) Full - 31 60 ns

CL = 15pF, SW = GND (Figure 3) Full - 24 60 ns

= 500Ω, CL = 100pF, SW = VCC (Figure 3)

Full - 65 800 ns

(Note 13)

= 500Ω, CL = 100pF, SW = GND (Figure 3)

Full - 420 800 ns

(Note 13)

R

= 54Ω, CL = 100pF (Figure 2) Full - 800 - kbps

DIFF

= VCC, ALL VERSIONS AND SPEEDS)

(Figure 4) Full 20 50 90 ns

(Figure 4) Full - 0.1 10 ns

Full - 40 - Mbps

RECEIVER ENABLE/DISABLE CHARACTERISTICS (ALL MODES AND VERSIONS AND SPEEDS)

Receiver Enable to Output Low t

Receiver Enable to Output High t

Receiver Disable from Output Low t

Receiver Disable from Output High t

Receiver Enable from Shutdown to
Output Low

Receiver Enable from Shutdown to
Output High

t

ZLSHDNCL

t

ZHSHDNCL

ZH

HZ

CL = 15pF, SW = VCC (Figure 5) Full - 22 60 ns

ZL

CL = 15pF, SW = GND (Figure 5) Full - 23 60 ns

CL = 15pF, SW = VCC (Figure 5) Full - 24 60 ns

LZ

CL = 15pF, SW = GND (Figure 5) Full - 25 60 ns

= 15pF, SW = VCC (Figure 5)

(Note 13)

= 15pF, SW = GND (Figure 5)

(Note 13)

RS-485 Mode Full - 260 700 ns

RS-232 Mode 25 - 35 - ns

RS-485 Mode Full - 260 700 ns

RS-232 Mode 25 - 25 - ns

NOTES:

7. All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to device ground unless
otherwise specified.

8. Supply current specification is valid for loaded drivers when DEN = 0V.

9. Applies to peak current. See “Typical Performance Curves” for more information.

defaults to RS-485 mode (>15kΩ) when the device is unpowered (VCC = 0V), regardless of the state of the 485/232 pin.

10. R

IN

11. V

12. The Slew pin has a pull-up resistor that enables only when in RS-485 mode (485/232

≤ 5.25V.

CC

= VCC).

13. ON, RXEN, and DEN all simultaneously switched Low-to-High.

10

FN6201.1

December 20, 2005

Test Circuits and Waveforms

ISL81387, ISL41387

V

CC

SIGNAL
GENERATOR

DEN

D

Y

DEN

V

CC

D

Y

Y

V

D

Z

R

OD

D

R

+

V

CM

-

R

V

OC

FIGURE 1. RS-485 DRIVER VOD AND VOC TEST CIRCUIT

D

Y

CL = 100pF

Y

D

Z

R

DIFF

= 100pF

C

L

OUT (Z)

OUT (Y)

DIFF OUT (Z - Y)

t

PLH

50% 50%

t

PHL

50% 50%

t

DLH

90% 90%

10% 10%

t

R

0V 0V

t

PHL

t

t

1.5V1.5V

PLH

DHL

3V

0V

V

OH

V

OL

V

OH

V

OL

+V

OD

-V

OD

t

F

FIGURE 2A. TEST CIRCUIT

FIGURE 2. RS-485 DRIVER PROPAGATION DELAY AND DIFFERENTIAL TRANSITION TIMES

DEN

DY

SIGNAL
GENERATOR

FOR SHDN TESTS, SWITCH ON AND DEN L- H SIMULTANEOUSLY

Y

D

Z

500Ω

C

L

SW

V
GND

PARAMETER OUTPUT RXEN DY SW CL (pF)

t

HZ

t

LZ

t

ZH

t

ZL

t

ZH(SHDN)

t

ZL(SHDN)

Y/Z X 0/1 GND 15

Y/Z X 1/0 V

CC

15

Y/Z X 0/1 GND 100

Y/Z X 1/0 V

CC

100

Y/Z 0 0/1 GND 100

Y/Z 0 1/0 V

CC

100

FIGURE 3A. TEST CIRCUIT

FIGURE 3. RS-485 DRIVER ENABLE AND DISABLE TIMES

11

CC

SKEW = |t

DEN

OUT (Y, Z)

t

OUT (Y, Z)

(Y or Z) - t

PLH

PHL

(Z or Y)|

FIGURE 2B. MEASUREMENT POINTS

ENABLED

t

ZH

t

ZH(SHDN)

ZL(SHDN)

t

ZL

OUTPUT HIGH

2.3V

2.3V
OUTPUT LOW

FIGURE 3B. MEASUREMENT POINTS

1.5V1.5V

t

HZ

t

LZ

3V

0V

VOH - 0.5V

VOL + 0.5V

December 20, 2005

V

OH

0V

V

CC

V

OL

FN6201.1

ISL81387, ISL41387

Test Circuits and Waveforms (Continued)

RXEN

V

CC

0V

SIGNAL
GENERATOR

A
B

R

A

R

15pF

FIGURE 4A. TEST CIRCUIT

FIGURE 4. RS-485 RECEIVER PROPAGATION DELAY

RXEN

A

SIGNAL
GENERATOR

FOR SHDN TESTS, SWITCH ON AND RXEN L- H SIMULTANEOUSLY

B

R

A

R

1kΩ

15pF

SW

V
GND

PAR AMETE R D EN B SW

t

HZ

t

LZ

t

ZH

t

ZL

t

ZH(SHDN)

t

ZL(SHDN)

X +1.5V GND

X-1.5VV

CC

X +1.5V GND

X-1.5VV

CC

0 +1.5V GND

0-1.5VV

CC

FIGURE 5A. TEST CIRCUIT

FIGURE 5. RS-485 RECEIVER ENABLE AND DISABLE TIMES

CC

B

t

PLH

R

A

1.5V 1.5V

FIGURE 4B. MEASUREMENT POINTS

ENABLED

RXEN

t

ZH

t

ZH(SHDN)

t

ZL(SHDN)

R

A

t

ZL

R

A

OUTPUT HIGH

1.5V

1.5V
OUTPUT LOW

FIGURE 5B. MEASUREMENT POINTS

t

t

HZ

t

0V0V

PHL

1.5V1.5V

LZ

+1.5V

-1.5V

3V

0V

VOH - 0.5V

VOL + 0.5V

V

CC

0V

V

OH

0V

V

CC

V

OL

V

CC

SIGNAL
GENERATOR

FIGURE 6A. TEST CIRCUIT

V

CC

SIGNAL
GENERATOR

FIGURE 7A. TEST CIRCUIT

DEN

D

Y,Z

RXEN

A, B

D

C

Y, Z

D

L

R

L

Y,Z

OUT (Y,Z)

SKEW = |t

t

DPHL

DPHL

- t

DPLH

0V 0V

|

1.5V1.5V

3V

0V

t

DPLH

V

O+

V

O-

FIGURE 6B. MEASUREMENT POINTS

FIGURE 6. RS-232 DRIVER PROPAGATION DELAY

2.4V

3V

0V

V

OH

V

OL

A, B

R

A, RB

R

CL = 15pF

R

A, RB

SKEW = |t

RPHL

- t

RPLH

t

RPHL

|

0.8V

1.7V1.3V

t

RPLH

FIGURE 7B. MEASUREMENT POINTS

FIGURE 7. RS-232 RECEIVER PROPAGATION DELAY

12

FN6201.1

December 20, 2005

ISL81387, ISL41387

Detailed Description

The ISLX1387 port 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 signalling, 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-485/422
maximum distance of 4000’ (1220m). It is important to note
that the ISLX1387 don’t follow the RS-485 convention
whereby the inverting I/O is labelled “B/Z”, and the
noninverting I/O is “A/Y”. Thus, in the application diagrams
below the 1387 A/Y (B/Z) pins connect to the B/Z (A/Y) pins
of the generic RS-485/422 ICs.

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

GENERIC 1/2 DUPLEX 485 XCVR

+

RO RE DE DI

ISLX1387

RA

*

RXEN

Tx/Rx

* QFN ONLY,

CONNECT RXEN TO GND

DEN

DY

D

+5V

V

CC

B

R

A

Y

Z

GND

+

R

0.1µF

0.1µF
+5V

T

R

V

CC

FIGURE 8. TYPICAL HALF DUPLEX RS-485 NETWORK

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 9. Tx and Rx enables aren’t required, so
connect RXEN and DEN to V

through a 1kΩ resistor.

CC

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 8. A 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.
A port contains two transceivers (2 Tx and 2 Rx) in RS-232
mode.

Protocol selection is handled via the 485/232

GENERIC 1/2 DUPLEX 485 XCVR

D

GND

B/Z

A/Y

0.1µF

R

+

T

A/Y

+5V

V

B/Z

GND

logic pin.

CC

R

RO

RE

DE

DI

D

ISL81387 (MASTER)

.

1kΩ

DY

DEN

RXEN

RA

GENERIC 422 Rx (SLAVE)

+

RO RE

+5V

+

0.1µF

V

CC

D

Z

Y

A

R

B

GND

R

T

0.1µF

+5V

R

V

CC

B

GND

A

GENERIC FULL DUPLEX 422 XCVR (SLAVE)

+5V

+

0.1µF

V

B

Z

Y

A

GND

CC

RO

R

DI

D

R

T

FIGURE 9. TYPICAL RS-422 NETWORK

13

FN6201.1

December 20, 2005

ISL81387, ISL41387

ISLX1387 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

- Better Noise immunity and/or distance;

OUT

Full Failsafe RS-485 Rx - Eliminates bus biasing;
Selectable RS-485 Data Rate - Up to 20Mbps, or slew

rate limited for low EMI and fewer termination issues;
High RS-232 Data Rate - >460kbps
Lower Tx and Rx Skews - Wider, consistent bit widths;
Lower I

- Max ICC is 2-4X lower than competition;

CC

Flow-Thru Pinouts - Tx, Rx bus pins on one side/logic

pins on the other, for easy routing to connector/UART;
Smaller (SSOP and QFN) and Pb-free Packaging.

RS-232 Mode

Rx Features

RS-232 receivers invert and convert RS-232 input levels
(±3V to ±25V) to the standard TTL/CMOS levels required by
a UART, ASIC, or µcontroller serial port. Receivers are
designed to operate at faster data rates than the drivers, and
they feature very low skews (10ns) so the receivers
contribute negligibly to bit width distortion. Inputs include the
standards required 3kΩ to 7kΩ pulldown resistor, so unused
inputs may be left unconnected. Rx inputs also have built-in
hysteresis to increase noise immunity, and to decrease
erroneous triggering due to slowly transitioning input signals.

Rx outputs are short circuit protected, and are tri-statable via
the active high RXEN pin, when the IC is shutdown (SHDN;
see Tables 2 and 3, and the “Low Power Shutdown” section),
or via the active low RXEN
option (see “ISL41387 Special Features” for more details).

Tx Features

RS-232 drivers invert and convert the standard TTL/CMOS
levels from a UART, or µcontroller serial port to RS-232
compliant levels (±5V minimum). The Tx delivers these
compliant output levels even at data rates of 650kbps, and
with loads of 1000pF. The drivers are designed for low skew
(typically 12% of the 500kbps bit width), and are compliant to
the RS-232 slew rate spec (4 to 30V/µs) for a wide range of
load capacitances. Tx inputs float if left unconnected, and
may cause I

increases. For the best results, connect

CC

unused inputs to GND.

Tx outputs are short circuit protected, and incorporate a
thermal SHDN feature to protect the IC in situations of
severe power dissipation. See the RS-485 section for more
details. Drivers tri-state via the active high DEN pin, in SHDN
(see Tables 2 and 3, and the “Low Power Shutdown”
section), or when the 5V power supply is off.

pin available on the QFN package

Charge Pumps

The on-chip charge pumps create the RS-232 transmitter
power supplies (typically +6/-7V) from a single supply as low
as 4.5V, and are enabled only if the port is configured for
RS-232 operation, and not in SHDN. The efficient design
requires only four small 0.1µF capacitors for the voltage
doubler and inverter functions. By operating discontinuously
(i.e., turning off as soon as V+ and V- pump up to the
nominal values), the charge pump contribution to RS-232
mode I

is reduced significantly. Unlike competing devices

CC

that require the charge pump in RS-485 mode, disabling the
charge pump saves power, and minimizes noise. If the
application is a dedicated RS-485 port, then the charge
pump capacitors aren’t even required.

Data Rates and Cabling

Drivers operate at data rates up to 650kbps, and are
guaranteed for data rates up to 460kbps. The charge pumps
and drivers are designed such that one driver can be
operated at the rated load, and at 460kbps (see Figure 33).
Figure 33 also shows that drivers can easily drive several
thousands of picofarads at data rates up to 250kbps, while
still delivering compliant ±5V output levels.

Receivers operate at data rates up to 2Mbps. They are
designed for a higher data rate to facilitate faster factory
downloading of software into the final product, thereby
improving the user’s manufacturing throughput.

Figures 36 and 37 illustrate driver and receiver waveforms at
250kbps, and 500kbps, respectively. For these graphs, one
driver drives the specified capacitive load, and a receiver.

RS-232 doesn’t require anything special for cabling; just a
single bus wire per transmitter and receiver, and another
wire for GND. So an ISLX1387 RS-232 port uses a five
conductor cable for interconnection. Bus terminations are
not required, nor allowed, by the RS-232 standard.

RS-485 Mode

Rx Features

RS-485 receivers convert differential input signals as small
as 200mV, as required by the RS-485 and RS-422
standards, to TTL/CMOS output levels. The differential Rx
provides maximum sensitivity, noise immunity, and common
mode rejection. Per the RS-485 standard, receiver inputs
function with common mode voltages as great as ±7V
outside the power supplies (i.e., +12V and -7V), making
them ideal for long networks where induced voltages are a
realistic concern. Each RS-485/422 port includes a single
receiver (RA), and the unused Rx output (RB) is disabled.

Worst case receiver input currents are 20% lower than the 1
“unit load” (1mA) RS-485 limit, which translates to a 15kΩ
minimum input resistance.

14

FN6201.1

December 20, 2005

ISL81387, ISL41387

These receivers include a “full fail-safe” function that
guarantees a high level receiver output if the receiver inputs
are unconnected (floating), shorted together, or if the bus is
terminated but undriven (i.e., differential voltage collapses to
near zero due to termination). Failsafe with shorted, or
terminated and undriven inputs is accomplished by setting
the Rx upper switching point at -40mV, thereby ensuring that
the Rx recognizes a 0V differential as a high level.

All the Rx outputs are short circuit protected, and are tri­statable via the active high RXEN pin, or when the IC is
shutdown (see Tables 2 and 3, and the “Low Power
Shutdown” section). ISL41387 (QFN) receiver outputs are
also tri-statable via an active low RXEN

input (see

“ISL41387 Special Features” for more details).

For the ISL41387 (QFN), when using the active high RXEN
function, the RXEN
high), or should be connected to V
If using the active low RXEN

pin may be left floating (internally pulled

through a 1kΩ resistor.

CC

, then the RXEN pin must be

connected to GND.

Tx Features

The RS-485/422 driver is a differential output device that
delivers at least 2.2V across a 54Ω load (RS-485), and at
least 2.5V across a 100Ω load (RS-422). Both levels
significantly exceed the standards requirements, and these
exceptional output voltages increase system noise immunity,
and/or allow for transmission over longer distances. The
drivers feature low propagation delay skew to maximize bit
widths, and to minimize EMI.

To allow multiple drivers on a bus, the RS-485 spec requires
that drivers survive worst case bus contentions undamaged.
The ISLX1387 drivers meet this requirement via driver
output short circuit current limits, and on-chip thermal
shutdown circuitry. The output stages incorporate current
limiting circuitry that ensures that the output current never
exceeds the RS-485 spec, even at the common mode
voltage range extremes. In the event of a major short circuit
condition, devices also include a thermal shutdown feature
that disables the drivers whenever the die temperature
becomes excessive. This eliminates the power dissipation,
allowing the die to cool. The drivers automatically re-enable
after the die temperature drops about 15 degrees. If the
contention persists, the thermal shutdown/re-enable cycle
repeats until the fault is cleared. Receivers stay operational
during thermal shutdown.

RS-485 multi-driver operation also requires drivers to include
tri-state functionality, so the port has a DEN pin to control
this function. If the driver is used in an RS-422 network, such
that driver tri-state isn’t required, then the DEN pin should
connect to V

through a 1kΩ resistor. Drivers are also tri-

CC

stated when the IC is in SHDN, or when the 5V power supply
is off.

Speed Options

The ISL81387 (SOIC/SSOP) features two speed options
that are user selectable via the SLEW pin: a high slew rate
setting optimized for 20Mbps data rates (Fast), and a slew
rate limited option for operation up to 460kbps (Med). The
ISL41387 (QFN) offers an additional, more slew rate limited,
option for data rates up to 115kbps (Slow). See the “Data
Rate“ and “Slew Rate Limited Data Rates” sections for more
information.

Receiver performance is the same for all three speed
options.

Data Rate, Cables, and Terminations

RS-485/422 are intended for network lengths up to 4000’
(1220m), but the maximum system data rate decreases as
the transmission length increases. Devices operating at the
maximum data rate of 20Mbps are limited to lengths of 20­30’ (6-9m), while devices operating at or below 115kbps can
operate at the maximum length of 4000’ (1220m).

Higher data rates require faster edges, so both the
ISLX1387 versions offer an edge rate capable of 20Mbps
data rates. They both have a second option for 460kbps, but
the ISL41387 also offers another, very slew rate limited,
edge rate to minimize problems at slow data rates.
Nevertheless, for the best jitter performance when driving
long cables, the faster speed settings may be preferable,
even at low data rates. See the “RS-485 Slew Rate Limited
Data Rates” section for details.

Twisted pair is the cable of choice for RS-485/422 networks.
Twisted pair cables tend to pick up noise and other
electromagnetically induced voltages as common mode
signals, which are effectively rejected by the differential
receivers in these ICs.

The preferred cable connection technique is “daisy­chaining”, where the cable runs from the connector of one
device directly to the connector of the next device, such that
cable stub lengths are negligible. A “backbone” structure,
where stubs run from the main backbone cable to each
device’s connector, is the next best choice, but care must be
taken to ensure that each stub is electrically “short”. See
Table 4 for recommended maximum stub lengths for each
speed option.

TABLE 4. RECOMMENDED STUB LENGTHS

SPEED OPTION

SLOW 350-500 (107-152)

MED 100-150 (30.5 - 46)

FAST 1-3 (0.3 - 0.9)

MAXIMUM STUB LENGTH

ft (m)

15

FN6201.1

December 20, 2005

ISL81387, ISL41387

Proper termination is imperative to minimize reflections
when using the 20Mbps speed option. Short networks using
the medium and slow speed options need not be terminated,
but terminations are recommended unless power dissipation
is an overriding concern. Note that the RS-485 spec allows a
maximum of two terminations on a network, otherwise the Tx
output voltage may not meet the required V

OD

.

In point-to-point, or point-to-multipoint (RS-422) networks,
the main cable should be terminated in its characteristic
impedance (typically 120Ω) at the end farthest from the
driver. In multi-receiver applications, stubs connecting
receivers to the main cable should be kept as short as
possible, but definitely shorter than the limits shown in Table

4. Multipoint (RS-485) systems require that the main cable
be terminated in its characteristic impedance at both ends.
Again, keep stubs connecting a transceiver to the main
cable as short as possible, and refer to Table 4. Avoid “star”,
and other configurations, where there are many “ends”
which would require more than the two allowed terminations
to prevent reflections.

High ESD

All pins on the ISLX1387 include ESD protection structures
rated at ±4kV (HBM), which is good enough to survive ESD
events commonly seen during manufacturing. But the bus
pins (Tx outputs and Rx inputs) are particularly vulnerable to
ESD events because they connect to an exposed port on the
exterior of the finished product. Simply touching the port
pins, or connecting a cable, can destroy an unprotected port.
ISLX1387 bus pins are fitted with advanced structures that
deliver ESD protection in excess of ±15kV (HBM), without
interfering with any signal in the RS-485 or the RS-232
range. This high level of protection may eliminate the need
for board level protection, or at the very least will increase
the robustness of any board level scheme.

Small Packages

Many competing dual protocol ICs are available only in
monstrously large 24 to 28 Ld SOIC packages. The
ISL81387’s 20 Ld SSOP is more than 50% smaller than
even a 24 Ld SOIC, and the ISL41387’s tiny 6x6mm QFN is
80% smaller than a 28 Ld SOIC.

Flow Through Pinouts

Even the ISLX1387 pinouts are features, in that the “flow­through” design simplifies board layout. Having the bus pins
all on one side of the package for easy routing to a cable
connector, and the Rx outputs and Tx inputs on the other
side for easy connection to a UART, avoids costly and
problematic crossovers. Figure 10 illustrates the flow­through nature of the pinout.

Low Power Shutdown (SHDN) Mode

The ISLX1387 enter the SHDN mode when ON = 0, and the
Tx and Rx are disabled (DEN = 0, RXEN = 0, and RXEN

1), and the already low supply current drops to as low as
5µA. SHDN disables the Tx and Rx outputs, and disables

=

the charge pumps if the port is in RS-232 mode, so V+
collapses to V

, and V- collapses to GND.

CC

All but 5µA of SHDN ICC current is due to control input (SPB,
SLEW, RXEN
I

varies depending on the ISLX1387 configuration. The

CC

) pull-up resistors (~20µA/resistor), so SHDN

spec tables indicate the worst case values, but careful
selection of the configuration yields lower currents. For
example, in RS-232 mode the SPB pin isn’t used, so floating
it or tying it high minimizes SHDN I

ISL81387

A
B

Y

CONNECTOR

FIGURE 10. ILLUSTRATION OF FLOW THROUGH PINOUT

Z

On the ISL41387, the SHDN I
decreases. V
its V

OH

powers each control pin input stage and sets

L

at VL rather than VCC. VCC powers the second

R

D

CC

.

CC

RA

DY

UART

OR

ASIC

OR

µCONTROLLER

increases as VL

stage, but the second stage input isn’t driven to the rail, so
some I

current flows. See Figure 20 for details.

CC

When enabling from SHDN in RS-232 mode, allow at least
20µs for the charge pumps to stabilize before transmitting
data. If fast enables are required, and I

isn’t the greatest

CC

concern, disable the drivers with the DEN pin to keep the
charge pumps active. The charge pumps aren’t used in
RS-485 mode, so the transceiver is ready to send or receive
data in less than 1µs, which is much faster than competing
devices that require the charge pump for all modes of
operation.

Internal Loopback Mode

Setting ON = 0, DEN = 1, and RXEN = 1 or RXEN = 0 (QFN
only), places the port in the loopback mode, a mode that
facilitates implementing board level self test functions. In
loopback, internal switches disconnect the Rx inputs from
the Rx outputs, and feed back the Tx outputs to the
appropriate Rx output. This way the data driven at the Tx
input appears at the corresponding Rx output (refer to
“Typical Operating Circuits”). The Tx outputs remain
connected to their terminals, so the external loads are
reflected in the loopback performance. This allows the
loopback function to potentially detect some common bus
faults such as one or both driver outputs shorted to GND, or
outputs shorted together.

Note that the loopback mode uses an additional set of
receivers, as shown in the “Typical Operating Circuits”.

16

FN6201.1

December 20, 2005

ISL81387, ISL41387

These loopback receivers are not standards compliant, so
the loopback mode can’t be used to implement a half-duplex
RS-485 transceiver.

ISL41387 (QFN Package) Special Features

Logic Supply (VL Pin)

The ISL41387 (QFN) includes a VL pin that powers the logic
inputs (Tx inputs and control pins) and Rx outputs. These
pins interface with “logic” devices such as UARTs, ASICs,
and µcontrollers, and today most of these devices use power
supplies significantly lower than 5V. Thus, a 5V output level
from a 5V powered dual protocol IC might seriously
overdrive and damage the logic device input. Similarly, the
the logic device’s low V
powered dual protocol input. Connecting the V
power supply of the logic device - as shown in Figure 11 ­limits the ISL41387’s Rx output V
and reduces the Tx and control input switching points to
values compatible with the logic device output levels.
Tailoring the logic pin input switching points and output levels
to the supply voltage of the UART, ASIC, or µcontroller
eliminates the need for a level shifter/translator between the
two ICs.

VCC = +5V

might not exceed the VIH of a 5V

OH

to VL (see Figure 14),

OH

VCC = +2V

pin to the

L

various V
particular V

The V
shown in Figures 19 and 20. All of the DC V

values so the user can ascertain whether or not a

L

voltage meets his needs.

L

TABLE 5. VIH AND VIL vs. VL FOR VCC = 5V

V

(V) VIH (V) VIL (V)

L

1.65V 0.79 0.50

1.8V 0.82 0.60

2.0V 0.87 0.69

2.5V 0.99 0.86

3.3V 1.19 1.05

supply current (IL) is typically less than 60µA, as

L

current is due

L

to inputs with internal pull-up resistors (SPB, SLEW, RXEN
being driven to the low input state. The worst case I

current

L

occurs when all three of the inputs are low (see Figure 19),
due to the I
input pull-up resistor is ~20µA, so the I
by about 40µA (at V

through the pull-up resistors. IIL through an

L

= 5V) when the SPB is high and 232

L

in Figure 19 drops

L

mode disables the SLEW pin pull-up (middle vs. top curve).
When all three inputs are driven high, I

drops to ~10nA, so

L

to minimize power dissipation drive these inputs high when
unneeded (e.g., SPB isn’t used in RS-232 mode, so drive it
high).

)

= 5V

V

OH

R

A

≥ 2V

V

IH

D

Y

GND

ISL81387

VCC = +5V

V

L

R

A

D

Y

GND

ISL41387

FIGURE 11. USING VL PIN TO ADJUST LOGIC LEVELS

V

can be anywhere from VCC down to 1.65V, but the input

L

V

V

OH

= 0.9V

IH

V

= 2V

V

R

T

≤ 2V

OH

UART/PROCESSOR

R

T

≤ 2V

OH

UART/PROCESSOR

XD

XD

VCC = +2V

XD

XD

ESD

DIODE

GND

ESD

DIODE

GND

switching points may not provide enough noise margin when
V

< 1.8V. Table 5 indicates typical VIH and VIL values for

L

Active Low Rx Enable (RXEN)

In many RS-485 applications, especially half duplex
configurations, users like to accomplish “echo cancellation”
by disabling the corresponding receiver while its driver is
transmitting data. This function is available on the QFN
package via an active low RXEN
also simplifies direction control, by allowing a single Tx/Rx

pin. The active low function

direction control line. If the active high RXEN were used,
either two valuable I/O pins would be used for direction
control, or an external inverter is required between DEN and
RXEN. Figure 12 details the advantage of using the RXEN
pin. When using RXEN

, ensure that RXEN is tied to GND.

RS-485 Slew Rate Limited Data Rates

The ISLX1387 FAST speed option (SLEW = High) utilizes Tx
output transitions optimized for a 20Mbps data rate. These
fast edges may increase EMI and reflection issues, even
though fast transitions aren’t required at the lower data rates
used by many applications. With the SLEW pin low, both
product types switch to a moderately slew rate limited output
transition targeted for 460kbps (MED) data rates. The
ISL41387 (QFN version) offers an additional, slew rate
limited data rate that is optimized for 115kbps (SLOW), and
is selected when SLEW = 0 and SPB = 0 (see Table 3). The
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

17

FN6201.1

December 20, 2005

ISL81387, ISL41387

1kΩ

OR NC

Tx/Rx

ACTIVE HIGH RX ENABLE

RXEN

RA

RXEN

Tx/Rx

RXEN *

RA

RXEN

DEN

DY

ISL41387

*

DEN

DY

* QFN ONLY

ISL41387

R

D

R

D

+5V

V

CC

B
A

Y

Z

GND

+5V

V

CC

B
A

Y

Z

GND

+

0.1µF

+

0.1µF

ACTIVE LOW RX ENABLE

FIGURE 12. USING ACTIVE LOW vs ACTIVE HIGH RX

ENABLE

large capacitance associated with long cables. Figures 42,
43, and 44 detail the jitter performance of the three speed
options while driving three different cable lengths. The
figures show that under all conditions the faster the edge
rate, the better the jitter performance. 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 likely better
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.

Evaluation Board

An evaluation board, part number ISL41387EVAL1, 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 eval board application note for details,
and contact your sales rep for ordering information.

18

FN6201.1

December 20, 2005

ISL81387, ISL41387

Typical Performance Curves V

50

40

30

20

10

RECEIVER OUTPUT CURRENT (mA)

0

012345

RECEIVER OUTPUT VOLTAGE (V)

V

OH

, 85°C

V

OH

= VL = 5V, TA = 25°C; Unless Otherwise Specified

CC

V

, 25°C

OL

V

, 85°C

OL

, 25°C

FIGURE 13. RECEIVER OUTPUT CURRENT vs RECEIVER

OUTPUT VOLTAGE

100

90

80

70

60

50

40

30

20

DRIVER OUTPUT CURRENT (mA)

10

0

012345

DIFFERENTIAL OUTPUT VOLTAGE (V)

FIGURE 15. RS-485, DRIVER OUTPUT CURRENT vs

DIFFERENTIAL OUTPUT VOLTAGE

5

4

3

IOH = -1mA

2

IOH = -8mA

1

HIGH OUTPUT VOLTAGE (V)

0

012345

VL (V)

IOH = -4mA

FIGURE 14. RECEIVER HIGH OUTPUT VOLTAGE vs LOGIC

SUPPLY VOLTAGE (V

3.6

3.5

3.4

3.3

3.2

3.1

DIFFERENTIAL OUTPUT VOLTAGE (V)

3

-40 0 50 85

-25 25 75
TEMPERATURE (°C)

R

DIFF

)

L

= 100Ω

R

DIFF

= 54Ω

FIGURE 16. RS-485, DRIVER DIFFERENTIAL OUTPUT

VOLTAGE vs TEMPERATURE

150

85°C

-40°C

Y OR Z = LOW

25°C

OUTPUT VOLTAGE (V)

100

50

0

-50

OUTPUT CURRENT (mA)

-100

-150

-7 -6 -4 -2 0 2 4 6 8 10 12

FULL TEMP RANGE

Y OR Z = HIGH

FIGURE 17. RS-485, DRIVER OUTPUT CURRENT vs SHORT

CIRCUIT VOLTAGE

19

4

3.5

3

2.5

(mA)

CC

I

2

1.5

1

-40 0 50 85

RS-232, RXEN, RXEN, ON = X, DEN = V

RS-232, RXEN, RXEN = X, ON = VCC, DEN = GND

RS-485, HALF DUPLEX, DEN = VCC, RXEN, RXEN, ON = X

RS-485, FULL DUPLEX, DEN = VCC, RXEN, RXEN, ON = X

RS-485, DEN = GND, RXEN, RXEN = X, ON = V

-25 25 75

TEMPERATURE (°C)

CC

FIGURE 18. SUPPLY CURRENT vs TEMPERATURE

December 20, 2005

CC

FN6201.1

ISL81387, ISL41387

Typical Performance Curves V

10m

NO LOAD
V

= VL or GND

IN

1m

DEN, RXEN, ON = GND

100µ

RS-485, SLEW, SPB, RXEN = GND

10µ

(A)
I

RS-232, RXEN = GND, SPB = V

L

1µ

100n

RS-232, SPB, RXEN = VL or

10n

RS-485, SLEW, SPB, RXEN = V

1n

23456

VL ≤ V

L

L

VL (V)

= VL = 5V, TA = 25°C; Unless Otherwise Specified (Continued)

CC

CCVL

> V

CC

FIGURE 19. RS-232, VL SUPPLY CURRENT vs VL VO LTA GE

(QFN ONLY)

1700

R

= 54Ω, CL = 100pF

DIFF

1650

1600

t

1550

1500

PROPAGATION DELAY (ns)

1450

DHL

t

DLH

t

DHL

500

400

300

(mA)

L

and I

200

CC

I

100

0

FIGURE 20. V

400

350

300

250

200

150

SKEW (ns)

100

50

RS-232/RS-485 I

SPB = V

RS-232 I

22.533.544.55

and VL SHDN SUPPLY CURRENTS vs VL

CC

VOLTAGE (QFN ONLY)

R

= 54Ω, CL = 100pF

DIFF

|t

DEN, RXEN, DY, DZ/SLEW, ON = GND

CC

L

L

VL (V)

- t

PLHY

|t

|

DLH

|t

- t

PLHZ

DHL

- t

PHLY

|

PHLZ

NO LOAD
V

= VL or GND

IN

= V

RXEN

SPB = GND

|

L

RS-485 I

L

1400

-40 0 50 85

-25 25 75

TEMPERATURE (°C)

FIGURE 21. RS-485, DRIVER PROPAGATION DELAY vs

TEMPERATURE (SLOW DATA RATE, QFN ONLY)

560

R

= 54Ω, CL = 100pF

DIFF

550

540

530

520

510

500

490

PROPAGATION DELAY (ns)

480

470

-40 0 50 85

t

DHL

t

DLH

t

DHL

-25 25 75

TEMPERATURE (°C)

FIGURE 23. RS-485, DRIVER PROPAGATION DELAY vs

TEMPERATURE (MEDIUM DATA RATE, QFN
ONLY)

-40 0 50 85

-25 25 75

TEMPERATURE (°C)

FIGURE 22. RS-485, DRIVER SKEW vs TEMPERATURE

(SLOW DATA RATE, QFN ONLY)

120

R

= 54Ω, CL = 100pF

DIFF

100

|t

- t

PHLZ

80

60

40

SKEW (ns)

20

0

-40 0 50 85

|

PLHY

|t

- t

PLHZ

-25 25 75

|

PHLY

|t

- t

DLH

DHL

TEMPERATURE (°C)

|

FIGURE 24. RS-485, DRIVER SKEW vs TEMPERATURE

(MEDIUM DATA RATE, QFN ONLY)

20

FN6201.1

December 20, 2005

ISL81387, ISL41387

Typical Performance Curves V

40

R

= 54Ω, CL = 100pF

DIFF

35

t

DHL

30

t

DLH

25

PROPAGATION DELAY (ns)

20

-40 0 50 85

-25 25 75
TEMPERATURE (°C)

= VL = 5V, TA = 25°C; Unless Otherwise Specified (Continued)

CC

FIGURE 25. RS-485, DRIVER PROPAGATION DELAY vs

TEMPERATURE (FAST DATA RATE)

R

= 60Ω, CL = 100pF

DIFF

D

Y

5
0

RECEIVER OUTPUT (V)

5

4

Y

3

2

Z

1

0

DRIVER OUTPUT (V)

R

A

TIME (400ns/DIV)

FIGURE 27. RS-485, DRIVER AND RECEIVER WAVEFORMS,

LOW TO HIGH (SLOW DATA RATE, QFN ONLY)

2.5

R

= 54Ω, CL = 100pF

DIFF

2

|t

- t

DLH

1.5

1

|t

- t

PLHZ

SKEW (ns)

0.5

|t

- t

PHLZ

0

-40 0 50 85

PLHY

-25 25 75

PHLY

|

TEMPERATURE (°C)

|

DHL

|

FIGURE 26. RS-485, DRIVER SKEW vs TEMPERATURE

(FAST DATA RATE)

R

= 60Ω, CL = 100pF

5
0

DRIVER INPUT (V)

5
0

RECEIVER OUTPUT (V)

5

4

3

2

1

0

DRIVER OUTPUT (V)

D

Y

Z

Y

TIME (400ns/DIV)

DIFF

R

A

5
0

DRIVER INPUT (V)

FIGURE 28. RS-485, DRIVER AND RECEIVER WAVEFORMS,

HIGH TO LOW (SLOW DATA RATE, QFN ONLY)

R

= 60Ω, CL = 100pF

DIFF

D

Y

5
0

RECEIVER OUTPUT (V)

5

4

Y

3

2

Z

1

0

DRIVER OUTPUT (V)

R

A

TIME (200ns/DIV)

5
0

FIGURE 29. RS-485, DRIVER AND RECEIVER WAVEFORMS,

LOW TO HIGH (MEDIUM DATA RATE, QFN ONLY)

21

R

= 60Ω, CL = 100pF

DIFF

D

Y

DRIVER INPUT (V)

5
0

RECEIVER OUTPUT (V)

5

4

Z

3

2

Y

1

0

DRIVER OUTPUT (V)

R

A

TIME (200ns/DIV)

5
0

DRIVER INPUT (V)

FIGURE 30. RS-485, DRIVER AND RECEIVER WAVEFORMS,

HIGH TO LOW (MEDIUM DATA RATE, QFN ONLY)

FN6201.1

December 20, 2005

ISL81387, ISL41387

Typical Performance Curves V

R

= 60Ω, CL = 100pF

DIFF

D

Y

5
0

RECEIVER OUTPUT (V)

5

4

Y

3

2

Z

1

0

DRIVER OUTPUT (V)

TIME (10ns/DIV)

R

A

= VL = 5V, TA = 25°C; Unless Otherwise Specified (Continued)

CC

FIGURE 31. RS-485, DRIVER AND RECEIVER WAVEFORMS,

LOW TO HIGH (FAST DATA RATE)

7.5

V

5

2.5

0

-2.5

+

OUT

ALL T

1 TRANSMITTER AT 250kbps or 500kbps,
OTHER TRANSMITTER AT 30kbps

LOADED WITH 3kΩ TO GND

OUTS

250kbps

500kbps

R

= 60Ω, CL = 100pF

5
0

DRIVER INPUT (V)

5
0

RECEIVER OUTPUT (V)

5

4

3

2

1

0

DRIVER OUTPUT (V)

D

Y

Z

Y

TIME (10ns/DIV)

DIFF

R

A

5
0

DRIVER INPUT (V)

FIGURE 32. RS-485, DRIVER AND RECEIVER WAVEFORMS,

HIGH TO LOW (FAST DATA RATE)

7.5

5

2.5

OUTPUTS STATIC
ALL T

0

-2.5

LOADED WITH 3kΩ TO GND

OUTS

V

OUT

+

500kbps

250kbps

TRANSMITTER OUTPUT VOLTAGE (V)

-7.5

-5
V

-

OUT

1000 2000 3000 4000 50000

LOAD CAPACITANCE (pF)

FIGURE 33. RS-232, TRANSMITTER OUTPUT VOLTAGE vs

LOAD CAPACITANCE

40

30

20

10

V

SHORTED TO GND

OUT

0

-10

-20

-30

TRANSMITTER OUTPUT CURRENT (mA)

-40

-40 0 50 85

-25 25 75
TEMPERATURE (°C)

Y or Z = LOW

Y or Z = HIGH

FIGURE 35. RS-232, TRANSMITTER SHORT CIRCUIT

CURRENT vs TEMPERATURE

RS-232 REGION OF NONCOMPLIANCE

-5

TRANSMITTER OUTPUT VOLTAGE (V)

-7.5

-40 0 50 85

-25 25 75
TEMPERATURE (°C)

V

OUT

-

FIGURE 34. RS-232, TRANSMITTER OUTPUT VOLTAGE vs

TEMPERATURE

CL = 3500pF, 2 CHANNELS SWITCHING

5

DY

0

5

0

Y/A

-5

5

RA

0

2µs/DIV.

FIGURE 36. RS-232, TRANSMITTER AND RECEIVER

WAVEFORMS AT 250kbps

22

FN6201.1

December 20, 2005

ISL81387, ISL41387

Typical Performance Curves V

CL = 1000pF, 2 CHANNELS SWITCHING

5

DY

0

5

0

Y/A

-5

5

RA

0

1µs/DIV.

= VL = 5V, TA = 25°C; Unless Otherwise Specified (Continued)

CC

FIGURE 37. RS-232, TRANSMITTER AND RECEIVER

WAVEFORMS AT 500kbps

1100

1000

900

800

700

600

500

400

DATA RATE (kbps)

300

1 TRANSMITTER AT 85°C

200

100

100 1000 2000 3000 4000 5000

ALL T

2 TRANSMITTERS AT 85°C

LOAD CAPACITANCE (pF)

LOADED WITH 5kΩ TO GND

OUTS

2 TRANSMITTERS AT 25°C

1 TRANSMITTER AT 25°C

V

OUT

≥ ±4V

FIGURE 39. RS-232, TRANSMITTER MAXIMUM DATA RATE vs

LOAD CAPACITANCE

450

2 TRANSMITTERS SWITCHING

400

350

300

ALL T

LOADED WITH 3kΩ TO GND, CL = 1000pF

OUTS

85°C

60

58

56

54

SR IN = 15V/µs

52

50

RECEIVER + DUTY CYCLE (%)

48

50

500 1000 1500 2000

DATA RATE (kbps)

FULL TEMP RANGE

VIN = ±5V

SR IN = 100V/µs

FIGURE 38. RS-232, RECEIVER OUTPUT +DUTY CYCLE vs

DATA RATE

7.5

V

5

2.5

0

-2.5

-5

TRANSMITTER OUTPUT VOLTAGE (V)

-7.5

+

OUT

2 TRANSMITTERS SWITCHING

ALL T

V

OUT

0 100 200 300 400 500 600 700 800

LOADED WITH 5kΩ TO GND, CL = 1000pF

OUTS

-

DATA RATE (kbps)

25°C

85°C

85°C

25°C

FIGURE 40. RS-232, TRANSMITTER OUTPUT VOLTAGE vs

DATA RATE

100

SLOW

10

MED

FAST

RS-232 REGION OF NONCOMPLIANCE

SKEW (ns)

250

200

150

50 150 250 350 450 550 650 750

DATA RATE (kbps)

25°C

JITTER (%)

1

0.1
32 100 200 300 400 500 600 700 800 900 1000

DOUBLE TERM’ED WITH 121Ω

DATA RATE (kbps)

FIGURE 41. RS-232, TRANSMITTER SKEW vs DATA RATE FIGURE 42. RS-485, TRANSMITTER JITTER vs DATA RATE

WITH 2000’ CAT 5 CABLE

23

FN6201.1

December 20, 2005

ISL81387, ISL41387

Typical Performance Curves V

100

SLOW

10

JITTER (%)

1

0.1
32 100 200 300 400 500 600 700 800 900 1000

DOUBLE TERM’ED WITH 121Ω

DATA RATE (kbps)

= VL = 5V, TA = 25°C; Unless Otherwise Specified (Continued)

CC

MED

FAST

FIGURE 43. RS-485, TRANSMITTER JITTER vs DATA RATE

WITH 1000’ CAT 5 CABLE

Die Characteristics

SUBSTRATE POTENTIAL (POWERED UP):

GND

TRANSISTOR COUNT:

2490

100

SLOW

10

JITTER (%)

1

0.1
32 100 200 300 400 500 600 700 800 900 1000

DOUBLE TERM’ED WITH 121Ω

DATA RATE (kbps)

MED

FAST

FIGURE 44. RS-485, TRANSMITTER JITTER vs DATA RATE

WITH 350’ CAT 5 CABLE

PROCESS:

BiCMOS

24

FN6201.1

December 20, 2005

ISL81387, ISL41387

Small Outline Plastic Packages (SOIC)

N

INDEX
AREA

123

-A-

0.25(0.010) B

H

E

-B-

SEATING PLANE

D

A

-C-

M

L

M

h x 45°

α

e

B

0.25(0.010) C AMB

M

NOTES:

1. Symbols are defined in the “MO Series Symbol List” in Section

2.2 of Publication Number 95.

2. Dimensioning and tolerancing per ANSI Y14.5M-1982.

3. Dimension “D” does not include mold flash, protrusions or gate
burrs. Mold flash, protrusion and gate burrs shall not exceed

0.15mm (0.006 inch) per side.

4. Dimension “E” does not include interlead flash or protrusions.
Interlead flash and protrusions shall not exceed 0.25mm (0.010
inch) per side.

5. The chamfer on the body is optional. If it is not present, a visual
index feature must be located within the crosshatched area.

6. “L” is the length of terminal for soldering to a substrate.

7. “N” is the number of terminal positions.

8. Terminal numbers are shown for reference only.

9. The lead width “B”, as measured 0.36mm (0.014 inch) or greater
above the seating plane, shall not exceed a maximum value of

0.61mm (0.024 inch)

10. Controlling dimension: MILLIMETER. Converted inch
dimensions are not necessarily exact.

A1

0.10(0.004)

S

M20.3 (JEDEC MS-013-AC ISSUE C)

20 LEAD WIDE BODY SMALL OUTLINE PLASTIC PACKAGE

INCHES MILLIMETERS

SYMBOL

A 0.0926 0.1043 2.35 2.65 -

A1 0.0040 0.0118 0.10 0.30 -

B 0.014 0.019 0.35 0.49 9

C 0.0091 0.0125 0.23 0.32 -

D 0.4961 0.5118 12.60 13.00 3

E 0.2914 0.2992 7.40 7.60 4

e 0.050 BSC 1.27 BSC -

H 0.394 0.419 10.00 10.65 -

C

h 0.010 0.029 0.25 0.75 5

L 0.016 0.050 0.40 1.27 6

N20 207

α

0° 8° 0° 8° -

NOTESMIN MAX MIN MAX

Rev. 2 6/05

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December 20, 2005

ISL81387, ISL41387

Shrink Small Outline Plastic Packages (SSOP)

N

INDEX
AREA

123

-A­D

e

B

0.25(0.010) C AMB

H

E

-B-

SEATING PLANE

A

-C-

A1

S

M

0.25(0.010) B

GAUGE

PLANE

α

0.10(0.004)

M

0.25

0.010

A2

M

L

NOTES:

1. Symbols are defined in the “MO Series Symbol List” in Section

2.2 of Publication Number 95.

2. Dimensioning and tolerancing per ANSI Y14.5M-1982.

3. Dimension “D” does not include mold flash, protrusions or gate
burrs. Mold flash, protrusion and gate burrs shall not exceed

0.20mm (0.0078 inch) per side.

4. Dimension “E” does not include interlead flash or protrusions. In­terlead flash and protrusions shall not exceed 0.20mm (0.0078
inch) per side.

5. The chamfer on the body is optional. If it is not present, a visual
index feature must be located within the crosshatched area.

6. “L” is the length of terminal for soldering to a substrate.

7. “N” is the number of terminal positions.

8. Terminal numbers are shown for reference only.

9. Dimension “B” does not include dambar protrusion. Allowable
dambar protrusion shall be 0.13mm (0.005 inch) total in excess
of “B” dimension at maximum material condition.

10. Controlling dimension: MILLIMETER. Converted inch dimen­sions are not necessarily exact.

M20.209 (JEDEC MO-150-AE ISSUE B)

20 LEAD SHRINK SMALL OUTLINE PLASTIC PACKAGE

INCHES MILLIMETERS

SYMBOL

A 0.068 0.078 1.73 1.99
A1 0.002 0.008’ 0.05 0.21
A2 0.066 0.070’ 1.68 1.78

B 0.010’ 0.015 0.25 0.38 9

C 0.004 0.008 0.09 0.20’
D 0.278 0.289 7.07 7.33 3

E 0.205 0.212 5.20’ 5.38 4

C

e 0.026 BSC 0.65 BSC

H 0.301 0.311 7.65 7.90’

L 0.025 0.037 0.63 0.95 6

N20 207

α

0 deg. 8 deg. 0 deg. 8 deg.

NOTESMIN MAX MIN MAX

Rev. 3 11/02

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FN6201.1

December 20, 2005

ISL81387, ISL41387

Quad Flat No-Lead Plastic Package (QFN)
Micro Lead Frame Plastic Package (MLFP)

L40.6x6

40 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE
(COMPLIANT TO JEDEC MO-220VJJD-2 ISSUE C)

MILLIMETERS

SYMBOL

A 0.80 0.90 1.00 -

A1 - - 0.05 -

A2 - - 1.00 9

A3 0.20 REF 9

b 0.18 0.23 0.30 5, 8

D 6.00 BSC -

D1 5.75 BSC 9

D2 3.95 4.10 4.25 7, 8

E 6.00 BSC -

E1 5.75 BSC 9

E2 3.95 4.10 4.25 7, 8

e 0.50 BSC -

k0.25 - - -

L 0.30 0.40 0.50 8

L1 - - 0.15 10

N402

Nd 10 3

Ne 10 3

P- -0.609

θ --129

NOTES:

1. Dimensioning and tolerancing conform to ASME Y14.5-1994.

2. N is the number of terminals.

3. Nd and Ne refer to the number of terminals on each D and E.

4. All dimensions are in millimeters. Angles are in degrees.

5. Dimension b applies to the metallized terminal and is measured
between 0.15mm and 0.30mm from the terminal tip.

6. The configuration of the pin #1 identifier is optional, but must be
located within the zone indicated. The pin #1 identifier may be
either a mold or mark feature.

7. Dimensions D2 and E2 are for the exposed pads which provide
improved electrical and thermal performance.

8. Nominal dimensions are provided to a ssist with PCB Land Pattern
Design efforts, see Intersil Technical Brief TB389.

9. Features and dimensions A2, A3, D1, E1, P & θ are present when
Anvil singulation method is used and not present for saw
singulation.

10. Depending on the method of lead termination at the edge of the
package, a maximum 0.15mm pull back (L1) maybe present. L
minus L1 to be equal to or greater than 0.3mm.

NOTESMIN NOMINAL MAX

Rev. 1 10/02

All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems.

Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality

Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without
notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.

For information regarding Intersil Corporation and its products, see www.intersil.com

27

FN6201.1

December 20, 2005