DATASHEET

±15kV ESD Protected, 5V, Dual Protocol
(RS-232/RS-485) Transceivers
ISL81387, ISL41387
Features
These devices are BiCMOS interface ICs that are user
configured as either a single RS-422, RS-485 differential
transceiver, or as a dual (2 Tx, 2 Rx) RS-232 transceiver.
• 5V powered, user selectable RS-232 or RS-485, RS-422
interface port (two RS-232 transceivers or one RS-485,
RS-422 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.
• ±15kV (HBM) ESD protected bus pins (RS-232 or RS-485)
In RS-485 mode, the transceivers support both the RS-485
and RS-422 differential communication standards. The
RS-485 receiver features "full fail-safe" 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, RS-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 (35µA) 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 (VL) that sets
the VOH level of logic outputs, and the 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.
For a dual port version of these devices, please see the
ISL81334, ISL41334 datasheet.
• True flow-through pinouts simplify board layouts
• Pb-Free (RoHS compliant)
• Large (2.7V) differential VOUT for improved noise immunity
in RS-485, RS-422 networks
• Full fail-safe (open/short) Rx in RS-485, RS-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 (VL) eases operation in mixed supply
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
Related Literature
• AN1378, “Implementing a Three Pin, Half-Duplex, Dual
Protocol (RS-232/RS-485) Interface Using the ISL81387 or
ISL41387.”
TABLE 1. SUMMARY OF FEATURES
PART
NUMBER
NO. OF
PORTS
PACKAGE OPTIONS
RS-485 DATA RATE
(bps)
RS-232 DATA
RATE (kbps)
VL PIN?
ACTIVE H or L Rx
ENABLE?
LOW POWER
SHUTDOWN?
ISL81387
1
20 Ld SOIC, 20 Ld SSOP
20M, 460k
650
NO
H
YES
ISL41387
1
40 Ld QFN (6mmx6mm)
20M, 460k, 115k
650
YES
BOTH
YES
June 9, 2014
FN6201.4
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas LLC 2005, 2007, 2014. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
ISL81387, ISL41387
Ordering Information
PART NUMBER
(Notes 1, 2)
PART
MARKING
TEMP. RANGE
(°C)
PACKAGE
(Pb-Free)
PKG.
DWG. #
ISL81387IAZ
81387 IAZ
-40 to +85
20 Ld SSOP
M20.209
ISL81387IBZ
ISL81387IBZ
-40 to +85
20 Ld SOIC
M20.3
ISL41387IRZ
41387 IRZ
-40 to +85
40 Ld QFN
L40.6x6
NOTES:
1. Add “-T*” suffix for tape and reel. Please refer to TB347 for details on reel specifications.
2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte
tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil Pbfree products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.
Pin Configurations
ISL81387
(20 LD SOIC, SSOP)
TOP VIEW
C1+ 1
20 C2+
C1- 2
19 C2-
V+
3
18 VCC
A 4
17 RA
B 5
16 RB
Y 6
15 DY
Z 7
14 DZ/SLEW
13 ON
485/232 8
DEN 9
12 RXEN
GND 10
11 V-
NC
NC
C1-
C1+
C2+
C2-
VCC
NC
NC
VL
ISL41387
(40 LD QFN)
TOP VIEW
40
39
38
37
36
35
34
33
32
31
V+
1
30 RA
A
2
29 RB
B
3
28 DY
Y
4
27 DZ/SLEW
Z
5
26 NC
EP
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2
9
22 NC
NC
10
21 ON
11
12
13
14
15
16
17
18
19
20
RXEN
NC
V-
23 NC
NC
8
RXEN
NC
GND
24 NC
GND
7
SPB
NC
NC
25 NC
DEN
6
485/232
NC
FN6201.4
June 9, 2014
ISL81387, ISL41387
TABLE 2. ISL81387 FUNCTION TABLE
INPUTS
RECEIVER OUTPUTS
DRIVER OUTPUTS
CHARGE
PUMPS
(Note 3)
LOOPBACK
(Note 4)
MODE
485/232
ON
RXEN
DEN
SLEW
RA
RB
Y
Z
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:
3. Charge pumps are on if in RS-232 mode and ON or DEN or RXEN are high.
4. Loopback is enabled when ON = 0, and DEN = RXEN = 1.
ISL81387 Truth Tables
RS-485 TRANSMITTING MODE
INPUTS (ON = 1)
RS-232 TRANSMITTING MODE
INPUTS (ON = 1)
OUTPUTS
485/232
DEN
DY
DZ
Y
Z
0
1
0
0
1
1
0
1
0
1
1
0
0
1
1
0
0
1
0
1
1
1
0
0
0
0
X
X
High-Z
High-Z
485/232
DEN
DY
SLEW
Y
Z
DATA RATE
(Mbps)
1
1
0
1
1
0
20
1
1
1
1
0
1
20
1
1
0
0
1
0
0.46
1
1
1
0
0
1
0.46
1
0
X
X
High-Z
High-Z
-
RS-485 RECEIVING MODE
RS-232 RECEIVING MODE
INPUTS (ON = 1)
INPUTS (ON = 1)
OUTPUT
485/232
RXEN
A
B
RA
RB
0
1
0
0
1
1
0
1
0
1
1
0
0
1
1
0
0
1
0
1
1
1
0
0
0
1
Open
Open
1
1
0
0
X
X
High-Z
High-Z
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OUTPUTS
OUTPUT
485/232
RXEN
B-A
RA
RB
1
1
 -40mV
1
High-Z
1
1
 -200mV
0
High-Z
1
1
Open or Shorted together
1
High-Z
1
0
X
High-Z
High-Z
FN6201.4
June 9, 2014
ISL81387, ISL41387
TABLE 3. ISL41387 FUNCTION TABLE
RECEIVER
OUTPUTS
INPUTS
DRIVER
OUTPUTS
Z
DRIVER
DATA
RATE
(Mbps)
CHARGE
PUMPS
(Note 5)
MODE
485/232
ON
RXEN
and/or
RXEN
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 6)
DEN
SLEW
SPB
RA
RB
Y
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 6)
1
0
0 or 1
1
1
X
ON
High-Z
ON
ON
20
OFF
RS-485 (Note 6)
NOTES:
5. Charge pumps are on if in RS-232 mode and ON or DEN or RXEN is high, or RXEN is low.
6. Loopback is enabled when ON = 0, and DEN = 1, and (RXEN = 1 or RXEN = 0).
ISL41387 Truth Tables
RS-485 TRANSMITTING MODE
INPUTS (ON = 1)
RS-232 TRANSMITTING MODE
INPUTS (ON = 1)
OUTPUTS
OUTPUTS
DATA
485/232
DEN
SLEW
SPB
DY
Y
Z
Mbps
485/232
DEN
DY
DZ
Y
Z
1
1
0
0
0/1
1/0
0/1
0.115
0
1
0
0
1
1
1
1
0
1
0/1
1/0
0/1
0.460
0
1
0
1
1
0
1
1
1
X
0/1
1/0
0/1
20
0
1
1
0
0
1
1
0
X
X
X
High-Z
High-Z
-
0
1
1
1
0
0
0
0
X
X
High-Z
High-Z
RS-232 RECEIVING MODE
INPUTS (ON = 1)
OUTPUT
RS-485 RECEIVING MODE
INPUTS (ON = 1)
OUTPUT
485/232
RXEN and/or RXEN
B-A
RA
RB
1
0 or 1
 -40mV
1
High-Z
485/232
RXEN and/or RXEN
A
B
RA
RB
1
0 or 1
 -200mV
0
High-Z
0
0 or 1
0
0
1
1
1
0 or 1
1
High-Z
0
0 or 1
0
1
1
0
Open or Shorted
together
0
0 or 1
1
0
0
1
1
1 and 0
X
High-Z
High-Z
0
0 or 1
1
1
0
0
0
0 or 1
Open
Open
1
1
0
1 and 0
X
X
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ISL81387, ISL41387
Pin Descriptions
PIN
MODE
FUNCTION
485/232
BOTH
Interface mode select input. High for RS-485 Mode and low for RS-232 Mode.
DEN
BOTH
Driver output enable. The driver outputs, Y and Z, are enabled by bringing DEN high. They are high impedance when DEN is low.
GND
BOTH
Ground connection. This is also the potential of the QFN's thermal exposed pad (EP).
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 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 is low, loopback is enabled.
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 package,
RXEN is high. When using the QFN and the active high Rx enable function, RXEN should be high or floating.
RXEN
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)
VCC
BOTH
System power supply input (5V).
VL
BOTH
Logic-Level Supply. All TTL/CMOS inputs and outputs are powered by this supply. (QFN only)
A
RS-232 Receiver input with 15kV ESD protection. A low on A forces RA high; a high on A forces RA low.
RS-485 Inverting receiver input with 15kV ESD protection.
B
RS-232 Receiver input with 15kV ESD protection. A low on B forces RB high; a high on B forces RB low.
RS-485 Noninverting receiver input with 15kV ESD protection.
DY
RS-232 Driver input. A low on DY forces output Y high. Similarly, a high on DY forces output Y low.
RS-485 Driver input. A low on DY forces output Y high and output Z low. Similarly, a high on DY forces output Y low and output Z high.
DZ
RS-232 Driver input. A low on DZ forces output Z high. Similarly, a high on DZ forces output Z low.
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 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.
SPB
RS-485 Speed control. Works in conjunction with the SLEW pin to select the 20Mbps, 460kbps or 115kbps RS-485 data rate. Internally
pulled high. (QFN only)
RA
RS-232 Receiver output.
RS-485 Receiver output: If B > A by at least -40mV, RA is high; If B < A by -200mV or more, RA is low; RA = High if A and B are unconnected
(floating) or shorted together (i.e., full fail-safe).
RB
RS-232 Receiver output.
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.
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.
V-
RS-232 Internally generated negative RS-232 transmitter supply (-5.5V). C4 not needed in RS-485 Mode.
/
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FN6201.4
June 9, 2014
ISL81387, ISL41387
Typical Operating Circuit
RS-232 MODE WITHOUT LOOPBACK
+5V
+
+5V
0.1µF
1
C1
0.1µF
+
C2
0.1µF
+
2
20
19
C1+
VCC
V+
C1C2+
3
V- 11
C2-
17
R
5k
5
B
+
18
4
A
RS-232 MODE WITH LOOPBACK
16
R
5k
+ C3
0.1µF
C4
0.1µF
+
C1
0.1µF
+
C2
0.1µF
+
18
C1+
2
VCC
V+
3
C1-
20
C2+
19
V- 11
5
B1
C4
0.1µF
+
17
R
RA
5k
RB
+ C3
0.1µF
C2-
4
A1
RA
0.1µF
1
16
R
5k
RB
LB
Rx
6
Y
15
D
7
Z
14
D
9
VCC
6
Y
DZ
VCC
RXEN
ON
485/232
13
9
C1
0.1µF
C2
0.1µF
A
B
485/232
Z
13
NOTE: PINOUT FOR SOIC AND SSOP
NOTE: PINOUT FOR SOIC AND SSOP
RS-485 MODE WITH LOOPBACK
+5V
0.1µF
2
19
+
18
C1+
VCC
C1C2+
V+
3
V- 11
C2-
4
17
R
5
+ C3
0.1µF
C4
0.1µF
+
+
2
20
C2
0.1µF
RA
0.1µF
1
C1
0.1µF
+
19
A
4
B
5
C1+
18
VCC
C1C2+
V+
17
R
15
D
14
9
VCC
16
DY
Y
VCC
RXEN
ON
485/232
6
15
D
7
SLEW
14
12
DEN
8
13
GND
+ C3
0.1µF
C4
0.1µF
+
RA
LB
Rx
6
7
3
V- 11
C2-
RB
Z
VCC
ON
GND
16
Y
VCC
RXEN
DEN
8
10
20
+
DZ
10
1
+
DY
12
VCC
VCC
RS-485 MODE WITHOUT LOOPBACK
+
14
D
GND
+5V
15
D
7
Z
12
DEN
8
DY
VCC
9
VCC
VCC
SLEW
12
VCC
RXEN
DEN
8
RB
DY
485/232
GND
ON
13
10
10
NOTE: PINOUT FOR SOIC AND SSOP
NOTE: PINOUT FOR SOIC AND SSOP
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June 9, 2014
ISL81387, ISL41387
Absolute Maximum Ratings (TA = +25°C)
Thermal Information
VCC to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7V
VL (QFN Only). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to VCC + 0.5V
Input Voltages
All Except A, B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to 7V
Input/Output Voltages
A, B (Any Mode) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -25V to +25V
Y, Z (Any Mode, Note 7) . . . . . . . . . . . . . . . . . . . . . . . . . -12.5V to +12.5V
RA, RB (non-QFN Package) . . . . . . . . . . . . . . . . . . . -0.5V to (VCC + 0.5V)
RA, RB (QFN Package) . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to (VL + 0.5V)
Output Short Circuit Duration
Y, Z, RA, RB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Indefinite
ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Specification Table
Thermal Resistance
JA (°C/W)
65
20 Ld SOIC Package (Note 9) . . . . . . . . . . . . . . . . . . . . .
20 Ld SSOP Package (Note 9) . . . . . . . . . . . . . . . . . . . .
60
40 Ld QFN Package (Note 8) . . . . . . . . . . . . . . . . . . . . .
32
Maximum Junction Temperature (Plastic Package) . . . . . . . . . . . +150°C
Maximum Storage Temperature Range . . . . . . . . . . . . . -65°C to +150°C
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see TB493
Operating Conditions
Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40°C to +85°C
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product
reliability and result in failures not covered by warranty.
NOTES:
7. One output at a time, IOUT  100mA for  10 mins.
8. JA is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See Tech
Brief TB379.
9. JA is measured with the component mounted on a high effective thermal conductivity test board in free air. See Tech Brief TB379 for details.
Electrical Specifications
Test Conditions: VCC = 4.5V to 5.5V, C1 - C4 = 0.1µF, VL = VCC (for QFN only), Unless Otherwise Specified.
Typicals are at VCC = 5V, TA = +25°C (Note 10).
PARAMETER
MAX
(Note 17) UNITS
TEMP
(°C)
MIN
(Note 17)
TYP
Full
-
-
VCC
V
R = 50 (RS-422) ( Figure 1)
Full
2.5
3.1
-
V
R = 27 (RS-485) (Figure 1)
Full
2.2
2.7
5
V
VOD3
RD = 60, R = 375, VCM = -7V to 12V (Figure 1)
Full
2
2.7
5
V
VOD
R = 27 or 50 (Figure 1)
Full
-
0.01
0.2
V
SYMBOL
TEST CONDITIONS
DC CHARACTERISTICS - RS-485 DRIVER (485/232 = VCC)
Driver Differential VOUT (no load)
VOD1
Driver Differential VOUT (with load)
VOD2
Change in Magnitude of Driver
Differential VOUT for
Complementary Output States
Driver Common-Mode VOUT
VOC
R = 27 or 50 (Figure 1) (Note 14)
Full
-
-
3.1
V
Change in Magnitude of Driver
Common-Mode VOUT for
Complementary Output States
VOC
R = 27 or 50 (Figure 1) (Note 14)
Full
-
0.01
0.2
V
Full
35
-
250
mA
VOUT = 12V
Full
-
-
150
µA
VOUT = -7V
Full
-150
-
-
µA
Driver Short-Circuit Current,
VOUT = High or Low
IOS
-7V  (VY or VZ)  12V (Note 12)
Driver Three-State Output Leakage
Current (Y, Z)
IOZ
Outputs Disabled,
VCC = 0V or 5.5V
DC CHARACTERISTICS - RS-232 DRIVER (485/232 = 0V)
Driver Output Voltage Swing
VO
All TOUTS Loaded with 3k to Ground
Full
±5.0
+6/-7
-
V
Driver Output Short-Circuit Current
IOS
VOUT = 0V
Full
-60
25/-35
60
mA
DC CHARACTERISTICS - LOGIC PINS (i.e., DRIVER AND CONTROL INPUT PINS)
Input High Voltage
Submit Document Feedback
7
VIH1
VL = VCC if QFN
Full
2
1.6
-
V
VIH2
VL = 3.3V (QFN Only)
Full
2
1.2
-
V
VIH3
VL = 2.5V (QFN Only)
Full
1.5
1
-
V
FN6201.4
June 9, 2014
ISL81387, ISL41387
Electrical Specifications
Test Conditions: VCC = 4.5V to 5.5V, C1 - C4 = 0.1µF, VL = VCC (for QFN only), Unless Otherwise Specified.
Typicals are at VCC = 5V, TA = +25°C (Note 10). (Continued)
PARAMETER
SYMBOL
Input Low Voltage
Input Current
TEMP
(°C)
TEST CONDITIONS
MIN
(Note 17)
TYP
MAX
(Note 17) UNITS
VIL1
VL = VCC if QFN
Full
-
1.4
0.8
V
VIL2
VL = 3.3V (QFN Only)
Full
-
1
0.7
V
VIL3
VL = 2.5V (QFN Only)
Full
-
0.8
0.5
V
IIN1
Except SLEW, RXEN (QFN), and SPB (QFN)
Full
-2
-
2
µA
IIN2
SLEW (Note 15), RXEN (QFN), and SPB (QFN)
Full
-25
-
25
µA
-7V  VCM  12V, Full fail-safe
Full
-0.2
-
-0.04
V
VCM = 0V
25
-
35
-
mV
VIN = 12V
Full
-
-
0.8
mA
VIN = -7V
Full
-0.64
-
-
mA
Full
15
-
-
k
DC CHARACTERISTICS - RS-485 RECEIVER INPUTS (485/232 = VCC)
Receiver Differential Threshold
Voltage
V TH
V TH
Receiver Input Hysteresis
Receiver Input Current (A, B)
IIN
Receiver Input Resistance
RIN
VCC = 0V or 4.5V to 5.5V
-7V  VCM  12V, VCC = 0 (Note 13), or
4.5V  VCC  5.5V
DC CHARACTERISTICS - RS-232 RECEIVER INPUTS (485/232 = GND)
Receiver Input Voltage Range
VIN
Full
-25
-
25
V
Receiver Input Threshold
VIL
Full
-
1.4
0.8
V
VIH
Full
2.4
1.9
-
V
Receiver Input Hysteresis
V TH
25
-
0.5
-
V
Receiver Input Resistance
RIN
Full
3
5
7
k
VIN = 15V, VCC Powered up (Note 13)
DC CHARACTERISTICS - RECEIVER OUTPUTS (485 OR 232 MODE)
Receiver Output High Voltage
VOH1
IO = -2mA (VL = VCC if QFN)
Full
3.5
4.6
-
V
VOH2
IO = -650A, VL = 3V (QFN Only)
Full
2.6
2.9
-
V
VOH3
IO = -500A, VL = 2.5V (QFN Only)
Full
2
2.4
-
V
Receiver Output Low Voltage
VOL
IO = 3mA
Full
-
0.1
0.4
V
Receiver Short-Circuit Current
IOSR
0V  VO  VCC
Full
7
-
85
mA
Receiver Three-State Output
Current
IOZR
Output Disabled, 0V  VO  VCC (or VL for QFN)
Full
-
-
10
µA
ICC232
485/232 = 0V, ON = VCC
Full
-
3.7
7
mA
ICC485
485/232 = VCC, ON = VCC
Full
-
1.6
5
mA
ISHDN232
ON = DEN = RXEN = 0V
(RXEN = SPB = VCC if QFN)
Full
-
5
30
µA
ISHDN485
ON = DEN = RXEN = SLEW = 0V
(RXEN = VCC, SPB = 0V if QFN)
Full
-
35
60
µA
Bus Pins (A, B, Y, Z) Any Mode
Human Body Model
25
-
15
-
kV
All Other Pins
Human Body Model
25
-
4
-
kV
POWER SUPPLY CHARACTERISTICS
No-Load Supply Current (Note 11)
Shutdown Supply Current
ESD CHARACTERISTICS
RS-232 DRIVER and RECEIVER SWITCHING CHARACTERISTICS (485/232 = 0V, ALL VERSIONS AND SPEEDS)
Driver Output Transition Region
Slew Rate
Submit Document Feedback
SR
8
RL = 3kMeasured From 3V to
-3V or -3V to 3V
CL  15pF
Full
-
18
30
V/µs
CL  2500pF
Full
4
12
-
V/µs
FN6201.4
June 9, 2014
ISL81387, ISL41387
Electrical Specifications
Test Conditions: VCC = 4.5V to 5.5V, C1 - C4 = 0.1µF, VL = VCC (for QFN only), Unless Otherwise Specified.
Typicals are at VCC = 5V, TA = +25°C (Note 10). (Continued)
PARAMETER
TEMP
(°C)
MIN
(Note 17)
TYP
RL = 3k, CL = 2500pF, 10% to 90%
Full
0.22
1.2
3.1
µs
RL = 3kCL = 1000pF (Figure 6)
Full
-
1
2
µs
Full
-
1.2
2
µs
tDPHL - tDPLH (Figure 6)
Full
-
240
400
ns
25
-
800
-
ns
RL = 5kMeasured at VOUT = ±3V
25
-
500
-
ns
VOUT = ±3.0V (Note 16)
25
-
20
-
µs
SYMBOL
Driver Output Transition Time
tr, tf
Driver Propagation Delay
tDPHL
TEST CONDITIONS
tDPLH
Driver Propagation Delay Skew
tDSKEW
Driver Enable Time
tDEN
Driver Disable Time
tDDIS
Driver Enable Time from Shutdown
tDENSD
MAX
(Note 17) UNITS
Driver Maximum Data Rate
DRD
RL = 3kCL = 1000pF, One Transmitter
Switching
Full
460
650
-
kbps
Receiver Propagation Delay
tRPHL
CL = 15pF (Figure 7)
Full
-
50
120
ns
Full
-
40
120
ns
tRPHL - tRPLH (Figure 7)
Full
-
10
40
ns
CL = 15pF
Full
0.46
2
-
Mbps
15
30
50
ns
tRPLH
Receiver Propagation Delay Skew
tRSKEW
Receiver Maximum Data Rate
DRR
RS-485 DRIVER SWITCHING CHARACTERISTICS (FAST DATA RATE (20Mbps), 485/232 = VCC, SLEW = VCC, ALL VERSIONS)
Driver Differential Input to Output
Delay
tDLH, tDHL
RDIFF = 54, CL = 100pF (Figure 2)
Full
Driver Output Skew
tSKEW
RDIFF = 54, CL = 100pF (Figure 2)
Full
-
0.5
10
ns
Driver Differential Rise or Fall Time
tR, tF
RDIFF = 54, CL = 100pF (Figure 2)
Full
3
11
20
ns
Full
-
27
60
ns
Driver Enable to Output Low
tZL
CL = 100pF, SW = VCC (Figure 3)
Driver Enable to Output High
tZH
CL = 100pF, SW = GND (Figure 3)
Full
-
24
60
ns
Driver Disable from Output Low
tLZ
CL = 15pF, SW = VCC (Figure 3)
Full
-
31
60
ns
Driver Disable from Output High
tHZ
CL = 15pF, SW = GND (Figure 3)
Full
-
24
60
ns
Driver Enable from Shutdown to
Output Low
tZL(SHDN)
RL = 500, CL = 100pF, SW = VCC (Figure 3)
(Note 16)
Full
-
65
250
ns
Driver Enable from Shutdown to
Output High
tZH(SHDN)
RL = 500, CL = 100pF, SW = GND (Figure 3)
(Note 16)
Full
-
152
250
ns
RDIFF = 54, CL = 100pF (Figure 2)
Full
-
30
-
Mbps
Driver Maximum Data Rate
fMAX
RS-485 DRIVER SWITCHING CHARACTERISTICS (MEDIUM DATA RATE (460kbps), 485/232 = VCC, SLEW = 0V, SPB = VCC (QFN Only), ALL VERSIONS)
Driver Differential Input to Output
Delay
tDLH, tDHL
RDIFF = 54, CL = 100pF (Figure 2)
Full
200
490
1000
ns
Driver Output Skew
tSKEW
RDIFF = 54, CL = 100pF (Figure 2)
Full
-
110
400
ns
Driver Differential Rise or Fall Time
tR, tF
RDIFF = 54, CL = 100pF (Figure 2)
Full
300
600
1100
ns
Driver Enable to Output Low
tZL
CL = 100pF, SW = VCC (Figure 3)
Full
-
30
300
ns
Driver Enable to Output High
tZH
CL = 100pF, SW = GND (Figure 3)
Full
-
128
300
ns
Driver Disable from Output Low
tLZ
CL = 15pF, SW = VCC (Figure 3)
Full
-
31
60
ns
Driver Disable from Output High
tHZ
CL = 15pF, SW = GND (Figure 3)
Full
-
24
60
ns
Driver Enable from Shutdown to
Output Low
tZL(SHDN)
RL = 500, CL = 100pF, SW = VCC (Figure 3)
(Note 16)
Full
-
65
500
ns
Driver Enable from Shutdown to
Output High
tZH(SHDN)
RL = 500, CL = 100pF, SW = GND (Figure 3)
(Note 16)
Full
-
255
500
ns
RDIFF = 54, CL = 100pF (Figure 2)
Full
-
2000
-
kbps
Driver Maximum Data Rate
Submit Document Feedback
fMAX
9
FN6201.4
June 9, 2014
ISL81387, ISL41387
Electrical Specifications
Test Conditions: VCC = 4.5V to 5.5V, C1 - C4 = 0.1µF, VL = VCC (for QFN only), Unless Otherwise Specified.
Typicals are at VCC = 5V, TA = +25°C (Note 10). (Continued)
PARAMETER
SYMBOL
TEMP
(°C)
TEST CONDITIONS
MIN
(Note 17)
TYP
MAX
(Note 17) UNITS
RS-485 DRIVER SWITCHING CHARACTERISTICS (SLOW DATA RATE (115kbps, QFN ONLY), 485/232 = VCC, SLEW = SPB = GND)
Driver Differential Input to Output
Delay
tDLH, tDHL
RDIFF = 54, CL = 100pF (Figure 2)
Full
800
1500
2500
ns
Driver Output Skew
tSKEW
RDIFF = 54, CL = 100pF (Figure 2)
Full
-
350
1250
ns
Driver Differential Rise or Fall Time
tR, tF
RDIFF = 54, CL = 100pF (Figure 2)
Full
1000
2000
3100
ns
Driver Enable to Output Low
tZL
CL = 100pF, SW = VCC (Figure 3)
Full
-
32
600
ns
Driver Enable to Output High
tZH
CL = 100pF, SW = GND (Figure 3)
Full
-
300
600
ns
Driver Disable from Output Low
tLZ
CL = 15pF, SW = VCC (Figure 3)
Full
-
31
60
ns
Driver Disable from Output High
tHZ
CL = 15pF, SW = GND (Figure 3)
Full
-
24
60
ns
Driver Enable from Shutdown to
Output Low
tZL(SHDN)
RL = 500, CL = 100pF, SW = VCC (Figure 3)
(Note 16)
Full
-
65
800
ns
Driver Enable from Shutdown to
Output High
tZH(SHDN)
RL = 500, CL = 100pF, SW = GND (Figure 3)
(Note 16)
Full
-
420
800
ns
RDIFF = 54, CL = 100pF (Figure 2)
Full
-
800
-
kbps
Driver Maximum Data Rate
fMAX
RS-485 RECEIVER SWITCHING CHARACTERISTICS (485/232 = VCC, ALL VERSIONS AND SPEEDS)
Receiver Input to Output Delay
tPLH, tPHL
(Figure 4)
Full
20
50
90
ns
Receiver Skew | tPLH - tPHL |
tSKEW
(Figure 4)
Full
-
3
10
ns
Receiver Maximum Data Rate
fMAX
Full
-
40
-
Mbps
RECEIVER ENABLE/DISABLE CHARACTERISTICS (ALL MODES AND VERSIONS AND SPEEDS)
Receiver Enable to Output Low
tZL
CL = 15pF, SW = VCC (Figure 5)
Full
-
22
60
ns
Receiver Enable to Output High
tZH
CL = 15pF, SW = GND (Figure 5)
Full
-
23
60
ns
Receiver Disable from Output Low
tLZ
CL = 15pF, SW = VCC (Figure 5)
Full
-
24
60
ns
Receiver Disable from Output High
tHZ
CL = 15pF, SW = GND (Figure 5)
Full
-
25
60
ns
Receiver Enable from Shutdown to
Output Low
tZLSHDN
CL = 15pF, SW = VCC (Figure 5)
(Note 16)
RS-485 Mode
Full
-
260
700
ns
RS-232 Mode
25
-
35
-
ns
Receiver Enable from Shutdown to
Output High
tZHSHDN
CL = 15pF, SW = GND (Figure 5)
(Note 16)
RS-485 Mode
Full
-
260
700
ns
RS-232 Mode
25
-
25
-
ns
NOTES:
10. 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.
11. Supply current specification is valid for loaded drivers when DEN = 0V.
12. Applies to peak current. See “Typical Performance Curves” beginning on page 18 for more information.
13. RIN defaults to RS-485 mode (>15k) when the device is unpowered (VCC = 0V), or in SHDN, regardless of the state of the 485/232 pin.
14. VCC  5.25V.
15. The Slew pin has a pull-up resistor that enables only when in RS-485 mode (485/232 = VCC).
16. ON, RXEN, and DEN all simultaneously switched Low-to-High.
17. Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established by characterization
and are not production tested.
Submit Document Feedback
10
FN6201.4
June 9, 2014
ISL81387, ISL41387
Test Circuits and Waveforms
R
DEN
VCC
Y
DY
RD
D
VOD
Z
+
-
VCM
VOC
R
FIGURE 1. RS-485 DRIVER VOD AND VOC TEST CIRCUIT
3V
DY
1.5V
1.5V
0V
tPLH
tPHL
VOH
VCC
CL = 100pF
DEN
50%
OUT (Z)
50%
VOL
Y
DY
tPHL
RDIFF
D
Z
CL = 100pF
tPLH
VOH
OUT (Y)
50%
SIGNAL
GENERATOR
50%
VOL
tDLH
tDHL
90%
DIFF OUT (Z - Y)
+VOD
90%
0V
10%
0V
10%
tR
-VOD
tF
SKEW = |tPLH (Y OR Z) - tPHL (Z OR Y)|
FIGURE 2A. TEST CIRCUIT
FIGURE 2B. MEASUREMENT POINTS
FIGURE 2. RS-485 DRIVER PROPAGATION DELAY AND DIFFERENTIAL TRANSITION TIMES
DEN
Y
DY
500
D
SIGNAL
GENERATOR
SW
Z
ENABLED
VCC
GND
DEN
1.5V
3V
1.5V
0V
CL
tZH
tZH(SHDN)
FOR SHDN TESTS, SWITCH ON AND DEN L- H SIMULTANEOUSLY
PARAMETER
OUTPUT
tHZ
Y/Z
tLZ
Y/Z
tZH
Y/Z
tZL
RXEN
OUT (Y, Z)
DY
SW
CL (pF)
X
0/1
GND
15
X
1/0
VCC
15
X
0/1
GND
100
Y/Z
X
1/0
VCC
100
tZH(SHDN)
Y/Z
0
0/1
GND
100
tZL(SHDN)
Y/Z
0
1/0
VCC
100
FIGURE 3A. TEST CIRCUIT
OUTPUT HIGH
tHZ
VOH - 0.5V VOH
2.3V
0V
tZL
tZL(SHDN)
OUT (Y, Z)
tLZ
VCC
2.3V
OUTPUT LOW
VOL + 0.5V V
OL
FIGURE 3B. MEASUREMENT POINTS
FIGURE 3. RS-485 DRIVER ENABLE AND DISABLE TIMES
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11
FN6201.4
June 9, 2014
ISL81387, ISL41387
Test Circuits and Waveforms (Continued)
+1.5V
RXEN
VCC
15pF
A
0V
R
B
B
0V
RA
0V
-1.5V
tPLH
tPHL
VCC
SIGNAL
GENERATOR
RA
1.5V
1.5V
0V
FIGURE 4A. TEST CIRCUIT
FIGURE 4B. MEASUREMENT POINTS
FIGURE 4. RS-485 RECEIVER PROPAGATION DELAY
RXEN
A
R
SIGNAL
GENERATOR
1k
RA
VCC
SW
B
GND
ENABLED
RXEN
1.5V
3V
1.5V
15pF
0V
tZH
tZH(SHDN)
OUTPUT HIGH
tHZ
VOH - 0.5V VOH
FOR SHDN TESTS, SWITCH ON AND RXEN L- H SIMULTANEOUSLY
RA
1.5V
0V
PARAMETER
DEN
B
SW
tHZ
X
+1.5V
GND
tLZ
X
-1.5V
VCC
tZL
tZL(SHDN)
tZH
X
+1.5V
GND
RA
tZL
X
-1.5V
VCC
tZH(SHDN)
0
+1.5V
GND
tZL(SHDN)
0
-1.5V
VCC
tLZ
VCC
1.5V
VOL + 0.5V V
OUTPUT LOW
OL
FIGURE 5B. MEASUREMENT POINTS
FIGURE 5A. TEST CIRCUIT
FIGURE 5. RS-485 RECEIVER ENABLE AND DISABLE TIMES
3V
DEN
VCC
DY,Z
DY, Z
1.5V
1.5V
CL
Y, Z
0V
D
tDPHL
VO+
RL
SIGNAL
GENERATOR
tDPLH
OUT (Y, Z)
0V
0V
VO-
SKEW = |tDPHL - tDPLH|
FIGURE 6B. MEASUREMENT POINTS
FIGURE 6A. TEST CIRCUIT
FIGURE 6. RS-232 DRIVER PROPAGATION DELAY
3V
RXEN
VCC
A, B
A, B
R
1.3V
1.7V
0V
CL = 15pF
RA, RB
tRPLH
tRPHL
2.4V
RA, RB
SIGNAL
GENERATOR
0.8V
VOH
VOL
SKEW = |tRPHL - tRPLH|
FIGURE 7A. TEST CIRCUIT
FIGURE 7B. MEASUREMENT POINTS
FIGURE 7. RS-232 RECEIVER PROPAGATION DELAY
Submit Document Feedback
12
FN6201.4
June 9, 2014
ISL81387, ISL41387
Detailed Description
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 VCC
through a 1k resistor.
The ISL81387, ISL41387 port supports dual protocols:
RS-485, RS-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, RS-422 maximum distance of
4000’ (1220m). It is important to note that the ISL81387,
ISL41387 don’t follow the RS-485 convention whereby the
inverting I/O is labelled “B/Z”, and the non-inverting I/O is “A/Y”.
Thus, in the following application diagrams, the ISL81387,
ISL41387 A/Y (B/Z) pins connect to the B/Z (A/Y) pins of the
generic RS-485, RS-422 ICs.
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, RS-422 mode includes one Rx and one Tx. See
application note AN1378 for details on implementing a three pin,
selectable RS-232/ half duplex RS-485 port.
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.
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 on each bus.
Protocol selection is handled via the 485/232 logic pin.
+
GENERIC 1/2 DUPLEX 485 XCVR
+5V
+
DI
+5V
B
+
0.1µF
VCC
GND
VCC
RO
R
B/Z
RE
Tx/Rx
A/Y
DEN
DY
GENERIC 1/2 DUPLEX 485 XCVR
+5V
D
A
RXEN *
DE
R
0.1F
VCC
R
RE
0.1µF
ISL81387, ISL41387
RA
RO
D
DE
B/Z
Y
D
A/Y
Z
GND
RT
RT
DI
GND
*QFN ONLY,
CONNECT RXEN TO GND
FIGURE 8. TYPICAL HALF DUPLEX RS-485 NETWORK
+
GENERIC 422 Rx (SLAVE)
RO
RE
GENERIC FULL DUPLEX 422 XCVR (SLAVE)
0.1F
+5V
ISL81387 (MASTER)
1k
DY
0.1F
+5V
VCC
+
GND
B
D
RXEN
VCC
RT
Z
A
Y
B
RO
R
Z
RT
A
R
0.1F
A
VCC
DEN
RA
+5V
R
+
DI
B
D
Y
GND
GND
FIGURE 9. TYPICAL RS-422 NETWORK
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13
FN6201.4
June 9, 2014
ISL81387, ISL41387
ISL81387, ISL41387 Advantages
CHARGE PUMPS
These dual protocol ICs offer many parametric improvements
versus those offered on competing dual protocol devices. Some
of the major improvements are:
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 ICC is reduced significantly. Unlike
competing devices 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.
• 15kV Bus Pin ESD - Eases board level requirements
• 2.7V Diff VOUT - Better Noise immunity and/or distance
• Full fail-safe RS-485 Rx - Eliminates bus biasing
• Selectable RS-485 Data Rate - Up to 20Mbps, or slewrate
limited for low EMI and fewer termination issues
• High RS-232 Data Rate - >460kbps
• Lower Tx and Rx Skews - Wider, consistent bit widths
• Lower ICC - Max ICC is 2x to 4x lower than competition
• 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 standard required 3k to 7k
pull-down 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 “Low Power Shutdown (SHDN) Mode” on page 16), or
via the active low RXEN pin available on the QFN package option
(see “ISL41387 (QFN Package) Special Features” on page 17 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 (4V/µs
to 30V/µs) for a wide range of load capacitances. Tx inputs float
if left unconnected, and may cause ICC increases. For the best
results, connect 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 “Low Power Shutdown (SHDN) Mode” on page 16), or when
the 5V power supply is off.
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14
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 ISL81387, ISL41387 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, RS-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 15k minimum
input resistance.
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). Fail-safe with shorted, or terminated and undriven
inputs is accomplished by setting the Rx upper switching point at
FN6201.4
June 9, 2014
ISL81387, ISL41387
-40mV, thereby ensuring that the Rx recognizes a 0V differential
as a high level.
All the Rx outputs are short circuit protected, and are tri-statable
via the active high RXEN pin, or when the IC is shutdown (see
Tables 2 and 3, and “Low Power Shutdown (SHDN) Mode” on
page 16). ISL41387 (QFN) receiver outputs are also tri-statable
via an active low RXEN input (see “ISL41387 (QFN Package)
Special Features” on page 17 for more details).
For the ISL41387 (QFN), when using the active high RXEN
function, the RXEN pin may be left floating (internally pulled
high), or should be connected to VCC through a 1k resistor. If
using the active low RXEN, then the RXEN pin must be connected
to GND.
TX FEATURES
The RS-485, RS-422 driver is a differential output device that
delivers at least 2.2V across a 54 load (RS-485), and at least
2.5V across a 100 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 specification
requires that drivers survive worst case bus contentions
undamaged. The ISL81387, ISL41387 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 specification, 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°. 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
VCC through a 1k resistor. Drivers are also tri-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 “Data Rate, Cables and Terminations”
on page 15 and “RS-485 Slew Rate Limited Data Rates” on
page 17 for more information.
Receiver performance is the same for all three speed options.
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15
DATA RATE, CABLES AND TERMINATIONS
RS-485, RS-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 20’ to
30’ (6m to 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 ISL81387,
ISL41387 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 “RS-485
Slew Rate Limited Data Rates” on page 17 for details.
Twisted pair is the cable of choice for RS-485, RS-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 “daisy-chaining”,
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
MAXIMUM STUB LENGTH
ft (m)
SLOW
350 to 500 (107 to 152)
MED
100 to 150 (30.5 to 46)
FAST
1 to 3 (0.3 to 0.9)
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 specification allows a
maximum of two terminations on a network, otherwise the Tx
output voltage may not meet the required VOD.
In point-to-point, or point-to-multipoint (RS-422) networks, the
main cable should be terminated in its characteristic impedance
(typically 120) 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.
FN6201.4
June 9, 2014
ISL81387, ISL41387
High ESD
All pins on the ISL81387, ISL41387 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. ISL81387,
ISL41387 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 6mmx6mm QFN is 80% smaller than a
28 Ld SOIC.
Flow-Through Pinouts
Even the ISL81387, ISL41387 pinouts are features, in that the
“flow-through” 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 flow-through nature of the
pinout..
CONNECTOR
ISL81387
A
B
Y
Z
R
On the ISL41387, the SHDN ICC increases as VL decreases. VL
powers each control pin input stage and sets its VOH at VL rather
than VCC. VCC powers the second stage, but the second stage
input isn’t driven to the rail, so some ICC current flows. See
Figure 20 for details.
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 ICC isn’t the greatest 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 Circuit” on page 6). 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 “Typical Operating Circuit” on page 6. These
loopback receivers are not standards compliant, so the loopback
mode can’t be used to implement a half-duplex RS-485
transceiver. See application note AN1378 for specific details on
implementing a three pin, half duplex dual protocol port.
RA
DY
D
UART
OR
ASIC
OR
µCONTROLLER
FIGURE 10. ILLUSTRATION OF FLOW-THROUGH PINOUT
Low Power Shutdown (SHDN) Mode
The ISL81387, ISL41387 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 VCC, and V- collapses
to GND.
All but 5µA of SHDN ICC current is due to control input (SPB,
SLEW) pull-up resistors (~20µA/resistor), so SHDN ICC varies
depending on the ISL81387, ISL41387 configuration. The
specification 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 ICC
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16
FN6201.4
June 9, 2014
ISL81387, ISL41387
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
controllers, 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 VOH
might not exceed the VIH of a 5V powered dual protocol input.
Connecting the VL pin to the power supply of the logic device (as
shown in Figure 11) limits the ISL41387’s Rx output VOH to VL
(see Figure 14), 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 controller eliminates
the need for a level shifter/translator between the two ICs.
VCC = +5V
RA
VCC = +2V
VOH = 5V
RXD
ESD
DIODE
VL values so the user can ascertain whether or not a particular VL
voltage meets his or her needs.
TABLE 5. VIH AND VIL vs VL FOR VCC = 5V
VL (V)
VIH (V)
VIL (V)
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
The VL supply current (IL) is typically less than 60µA, as shown in
Figures 19 and 20. All of the DC VL current is due to inputs with
internal pull-up resistors (SPB, SLEW, RXEN) being driven to the
low input state. The worst case IL current occurs when all three of
the inputs are low (see Figure 19), due to the IL through the
pull-up resistors. IIL through an input pull-up resistor is ~20µA, so
the IL in Figure 19 drops by about 40µA (at VL = 5V) when the
SPB is high and 232 mode disables the SLEW pin pull-up (middle
vs top curve). When all three inputs are driven high, IL drops to
~10nA, so to minimize power dissipation drive these inputs high
when unneeded (e.g., SPB isn’t used in RS-232 mode, so drive it
high).
Active Low Rx Enable (RXEN)
VIH  2V
DY
VOH  2V
TXD
GND
GND
ISL81387
UART/PROCESSOR
VCC = +5V
VCC = +2V
VL
RA
VOH = 2V
RXD
VIH = 0.9V
DY
VOH  2V
GND
ESD
DIODE
TXD
GND
ISL41387
UART/PROCESSOR
FIGURE 11. USING VL PIN TO ADJUST LOGIC LEVELS
VL can be anywhere from VCC down to 1.65V, but the input
switching points may not provide enough noise margin when
VL < 1.8V. Table 5 indicates typical VIH and VIL values for various
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17
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 pin. The active low function also simplifies
direction control, by allowing a single Tx/Rx 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 ISL81387, ISL41387 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 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
FN6201.4
June 9, 2014
ISL81387, ISL41387
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.
1k
OR NC
ISL41387 +5V
+
RXEN *
RA
Tx/Rx
0.1µF
VCC
B
R
RXEN
A
DEN
Y
DY
Z
D
Evaluation Board
GND
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 evaluation board application
note for details and contact your sales rep for ordering
information.
ACTIVE HIGH RX ENABLE
ISL41387 +5V
+
0.1µF
VCC
RXEN
RA
R
B
RXEN *
A
DEN
Y
Tx/Rx
DY
D
Z
GND
* QFN ONLY
ACTIVE LOW RX ENABLE
FIGURE 12. USING ACTIVE LOW vs ACTIVE HIGH RX ENABLE
Typical Performance Curves
VCC = VL = 5V, TA = +25°C; Unless Otherwise Specified.
5
VOL, +25°C
HIGH OUTPUT VOLTAGE (V)
RECEIVER OUTPUT CURRENT (mA)
50
40
VOL, +85°C
30
20
VOH, +25°C
VOH, +85°C
10
4
3
IOH = -1mA
2
IOH = -8mA
1
IOH = -4mA
0
0
0
1
2
3
4
RECEIVER OUTPUT VOLTAGE (V)
5
FIGURE 13. RECEIVER OUTPUT CURRENT vs RECEIVER OUTPUT
VOLTAGE
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18
0
1
2
3
4
5
VL (V)
FIGURE 14. RECEIVER HIGH OUTPUT VOLTAGE vs LOGIC SUPPLY
VOLTAGE (VL) (QFN ONLY)
FN6201.4
June 9, 2014
ISL81387, ISL41387
Typical Performance Curves
VCC = VL = 5V, TA = +25°C; Unless Otherwise Specified. (Continued)
100
DIFFERENTIAL OUTPUT VOLTAGE (V)
3.6
DRIVER OUTPUT CURRENT (mA)
90
80
70
60
50
40
30
20
10
0
0
1
2
3
4
DIFFERENTIAL OUTPUT VOLTAGE (V)
3.5
RDIFF = 100
3.4
3.3
3.2
3.0
-40
5
85
75
4.0
RS-232, RXEN, RXEN, ON = X, DEN = VCC
Y OR Z = LOW
100
3.5
FULL TEMP RANGE
RS-232, RXEN, RXEN = X, ON = VCC, DEN = GND
3.0
ICC (mA)
50
0
Y OR Z = HIGH
-50
2.5
2.0
RS-485, HALF DUPLEX, DEN = VCC, RXEN, RXEN, ON = X
+25°C
+85°C
1.5
-100
-40°C
-7 -6
-4
-2
0
2
4
6
OUTPUT VOLTAGE (V)
8
10
1.0
-40
12
10m
100µ
RS-485, DEN = GND, RXEN, RXEN = X, ON = VCC
0
-25
50
25
75
85
FIGURE 18. SUPPLY CURRENT vs TEMPERATURE
500
NO LOAD
VIN = VL or GND
DEN, RXEN, ON = GND
1m
RS-485, FULL DUPLEX, DEN = VCC, RXEN, RXEN, ON = X
TEMPERATURE (°C)
FIGURE 17. RS-485, DRIVER OUTPUT CURRENT vs SHORT CIRCUIT
VOLTAGE
VL  VCC
VL > VCC
400
RS-485, SLEW, SPB, RXEN = GND
ICC AND IL (µA)
IL (A)
50
25
FIGURE 16. RS-485, DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs
TEMPERATURE
150
-150
0
-25
TEMPERATURE (°C)
FIGURE 15. RS-485, DRIVER OUTPUT CURRENT vs DIFFERENTIAL
OUTPUT VOLTAGE
OUTPUT CURRENT (mA)
RDIFF = 54
3.1
10µ
RS-232, RXEN = GND, SPB = VL
1µ
DEN, RXEN, DY, DZ/SLEW, ON = GND
NO LOAD
VIN = VL OR GND
RXEN = VL
RS-232/RS-485 ICC
300
200
100n
100
RS-232, SPB, RXEN = VL OR
10n
RS-485, SLEW, SPB, RXEN = VL
1n
2
3
4
VL (V)
5
FIGURE 19. VL SUPPLY CURRENT vs VL VOLTAGE (QFN ONLY)
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19
6
0
2.0
SPB = VL
RS-232 IL
2.5
SPB = GND
RS-485 IL
3.0
3.5
VL (V)
4.0
4.5
5.0
FIGURE 20. VCC AND VL SHDN SUPPLY CURRENTS vs VL VOLTAGE
(QFN ONLY)
FN6201.4
June 9, 2014
ISL81387, ISL41387
Typical Performance Curves
VCC = VL = 5V, TA = +25°C; Unless Otherwise Specified. (Continued)
400
1700
RDIFF = 54, CL = 100pF
RDIFF = 54, CL = 100pF
350
|tPHLZ - tPLHY|
300
|tPLHZ - tPHLY|
1600
SKEW (ns)
PROPAGATION DELAY (ns)
1650
tDHL
1550
tDLH
1500
250
200
150
100
tDHL
1450
|tDLH - tDHL|
50
1400
-40
0
-25
50
25
75
85
-40
0
-25
TEMPERATURE (°C)
25
50
75
85
75
85
TEMPERATURE (°C)
FIGURE 21. RS-485, DRIVER PROPAGATION DELAY vs
TEMPERATURE (SLOW DATA RATE, QFN ONLY)
FIGURE 22. RS-485, DRIVER SKEW vs TEMPERATURE
(SLOW DATA RATE, QFN ONLY)
560
120
RDIFF = 54, CL = 100pF
RDIFF = 54, CL = 100pF
550
530
|tPHLZ - tPLHY|
80
SKEW (ns)
PROPAGATION DELAY (ns)
100
540
520
tDHL
510
tDLH
60
|tPLHZ - tPHLY|
500
40
tDHL
490
20
480
|tDLH - tDHL|
470
-40
-25
0
50
25
75
0
-40
85
0
25
TEMPERATURE (°C)
-25
TEMPERATURE (°C)
FIGURE 23. RS-485, DRIVER PROPAGATION DELAY vs
TEMPERATURE (MEDIUM DATA RATE)
FIGURE 24. RS-485, DRIVER SKEW vs TEMPERATURE
(MEDIUM DATA RATE)
2.5
40
RDIFF = 54, CL = 100pF
RDIFF = 54, CL = 100pF
2.0
35
|tDLH - tDHL|
SKEW (ns)
PROPAGATION DELAY (ns)
50
tDHL
30
tDLH
1.5
1.0
|tPLHZ - tPHLY|
25
0.5
20
-40
-25
0
25
50
TEMPERATURE (°C)
FIGURE 25. RS-485, DRIVER PROPAGATION DELAY vs
TEMPERATURE (FAST DATA RATE)
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20
75
85
|tPHLZ - tPLHY|
0
-40
-25
0
25
50
75
85
TEMPERATURE (°C)
FIGURE 26. RS-485, DRIVER SKEW vs TEMPERATURE (FAST DATA
RATE)
FN6201.4
June 9, 2014
ISL81387, ISL41387
0
RA
0
5
3
2
Y
Z
1
0
5
RA
0
5
4
Z
3
2
1
Y
0
TIME (400ns/DIV)
TIME (400ns/DIV)
0
5
RA
0
5
4
3
2
RECEIVER OUTPUT (V)
5
DRIVER INPUT (V)
RDIFF = 60, CL = 100pF
FIGURE 28. RS-485, DRIVER AND RECEIVER WAVEFORMS, HIGH TO
LOW (SLOW DATA RATE, QFN ONLY)
DRIVER OUTPUT (V)
DRIVER OUTPUT (V)
RECEIVER OUTPUT (V)
FIGURE 27. RS-485, DRIVER AND RECEIVER WAVEFORMS, LOW TO
HIGH (SLOW DATA RATE, QFN ONLY)
DY
Y
Z
1
0
RDIFF = 60, CL = 100pF
5
DY
5
RA
5
4
3
Z
2
1
Y
0
TIME (200ns/DIV)
5
0
RA
0
5
4
Y
3
2
Z
1
0
TIME (10ns/DIV)
FIGURE 31. RS-485, DRIVER AND RECEIVER WAVEFORMS,
LOW TO HIGH (FAST DATA RATE)
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RECEIVER OUTPUT (V)
RDIFF = 60, CL = 100pF
DRIVER INPUT (V)
FIGURE 30. RS-485, DRIVER AND RECEIVER WAVEFORMS,
HIGH TO LOW (MEDIUM DATA RATE)
DRIVER OUTPUT (V)
DRIVER OUTPUT (V)
RECEIVER OUTPUT (V)
FIGURE 29. RS-485, DRIVER AND RECEIVER WAVEFORMS,
LOW TO HIGH (MEDIUM DATA RATE)
5
21
0
0
TIME (200ns/DIV)
DY
0
DRIVER INPUT (V)
4
5
DY
RDIFF = 60, CL = 100pF
5
DY
5
0
RA
DRIVER INPUT (V)
5
RDIFF = 60, CL = 100pF
DRIVER INPUT (V)
5
RECEIVER OUTPUT (V)
RDIFF = 60, CL = 100pF
DY
DRIVER INPUT (V)
VCC = VL = 5V, TA = +25°C; Unless Otherwise Specified. (Continued)
DRIVER OUTPUT (V)
DRIVER OUTPUT (V)
RECEIVER OUTPUT (V)
Typical Performance Curves
0
5
4
Z
3
2
1
Y
0
TIME (10ns/DIV)
FIGURE 32. RS-485, DRIVER AND RECEIVER WAVEFORMS,
HIGH TO LOW (FAST DATA RATE)
FN6201.4
June 9, 2014
ISL81387, ISL41387
Typical Performance Curves
VCC = VL = 5V, TA = +25°C; Unless Otherwise Specified. (Continued)
7.5
VOUT+
5.0
2.5
ALL TOUTS LOADED WITH 3k TO GND
500kbps
0
1 TRANSMITTER AT 250kbps OR 500kbps,
OTHER TRANSMITTER AT 30kbps
-2.5
500kbps
-5.0
VOUT -
250kbps
-7.5
0
1000
2000
3000
4000
TRANSMITTER OUTPUT VOLTAGE (V)
250kbps
RS-232 REGION OF NONCOMPLIANCE
TRANSMITTER OUTPUT VOLTAGE (V)
7.5
5.0
VOUT+
2.5
OUTPUTS STATIC
ALL TOUTS LOADED WITH 3k TO GND
0
-2.5
-5.0
VOUT -
-7.5
-40
5000
0
25
TEMPERATURE (°C)
-25
LOAD CAPACITANCE (pF)
FIGURE 33. RS-232, TRANSMITTER OUTPUT VOLTAGE vs LOAD
CAPACITANCE
50
75
85
FIGURE 34. RS-232, TRANSMITTER OUTPUT VOLTAGE vs
TEMPERATURE
TRANSMITTER OUTPUT CURRENT (mA)
40
CL = 3500pF, 1 CHANNEL SWITCHING
30
5
Y or Z = LOW
DY
20
0
10
5
VOUT SHORTED TO GND
0
0
-10
-5
Y/A
-20
5
Y or Z = HIGH
-30
0
-40
-40
-25
0
25
TEMPERATURE (°C)
50
75
RA
85
FIGURE 35. RS-232, TRANSMITTER SHORT CIRCUIT CURRENT vs
TEMPERATURE
2s/DIV
FIGURE 36. RS-232, TRANSMITTER AND RECEIVER WAVEFORMS AT
250kbps
60
VIN = ±5V
CL = 1000pF, 1 CHANNEL SWITCHING
RECEIVER + DUTY CYCLE (%)
5
DY
0
5
0
Y/A
-5
5
RA
0
FULL TEMP RANGE
58
56
54
SR IN = 15V/µs
52
SR IN = 100V/µs
50
48
1s/DIV.
50
500
1000
1500
2000
DATA RATE (kbps)
FIGURE 37. RS-232, TRANSMITTER AND RECEIVER WAVEFORMS AT
500kbps
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22
FIGURE 38. RS-232, RECEIVER OUTPUT +DUTY CYCLE vs DATA RATE
FN6201.4
June 9, 2014
ISL81387, ISL41387
Typical Performance Curves
800
700
2 TRANSMITTERS AT +25°C
600
1 TRANSMITTER AT +25°C
500
400
300
200
1 TRANSMITTER AT +85°C
2 TRANSMITTERS AT +85°C
100
VOUT+
5.0
+25°C
+85°C
2.5
2 TRANSMITTERS SWITCHING
0
ALL TOUTS LOADED WITH 5k TO GND, CL = 1000pF
-2.5
+85°C
-5.0
VOUT -
+25°C
RS-232 REGION OF NONCOMPLIANCE
ALL TOUTS LOADED WITH 5k TO GND
900
DATA RATE (kbps)
7.5
VOUT 4V
1000
TRANSMITTER OUTPUT VOLTAGE (V)
1100
VCC = VL = 5V, TA = +25°C; Unless Otherwise Specified. (Continued)
-7.5
100
1000
2000
3000
LOAD CAPACITANCE (pF)
4000
5000
0
100
200
300
400
500
600
700
800
DATA RATE (kbps)
FIGURE 39. RS-232, TRANSMITTER MAXIMUM DATA RATE vs LOAD
CAPACITANCE
FIGURE 40. RS-232, TRANSMITTER OUTPUT VOLTAGE vs DATA RATE
100
450
2 TRANSMITTERS SWITCHING
400
ALL TOUTS LOADED WITH 3k TO GND, CL = 1000pF
FAST
10
JITTER (%)
350
SKEW (ns)
MED
SLOW
+85°C
300
250
1
+25°C
200
150
50
DOUBLE TERM’ED WITH 121
0.1
150
250
350
450
550
650
750
32 100
200
300
400
DATA RATE (kbps)
500
600
700
800
900 1000
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
100
100
SLOW
SLOW
MED
MED
FAST
1
JITTER (%)
10
JITTER (%)
10
FAST
1
DOUBLE TERM’ED WITH 121
0.1
32 100
200
300
400
500
600
700
800
900 1000
DATA RATE (kbps)
FIGURE 43. RS-485, TRANSMITTER JITTER vs DATA RATE WITH 1000’
CAT-5 CABLE
Submit Document Feedback
23
DOUBLE TERM’ED WITH 121
0.1
32 100
200
300
400
500
600
700
800
900 1000
DATA RATE (kbps)
FIGURE 44. RS-485, TRANSMITTER JITTER vs DATA RATE WITH 350’
CAT-5 CABLE
FN6201.4
June 9, 2014
ISL81387, ISL41387
Die Characteristics
TRANSISTOR COUNT:
SUBSTRATE AND QFN THERMAL PAD POTENTIAL
(POWERED UP):
2490
PROCESS:
BiCMOS
GND
Revision History
The revision history provided is for informational purposes only and is believed to be accurate, but not warranted. Please go to the web to make sure that
you have the latest revision.
DATE
REVISION
May 12, 2014
FN6201.4
CHANGE
Reformatted entire datasheet to Intersil lastest template. Added Revision History
Page 1:
- Changed 20µA to 35µA in paragraph 4.
- Added Related Literature
Updated Note 17
Figure 14 added QFN ONLY to figure name.
Figure 19 Removed RS-232 from figure name.
Figure 20 Changed Y-axis units from mA to µA.
Figures 23, 24, 29, and 30 removed QFN ONLY from the Figure name.
Replaced POD on page 26 to latest revision.
About Intersil
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address some of the largest markets within the industrial and infrastructure, mobile computing and high-end consumer markets.
For the most updated datasheet, application notes, related documentation and related parts, please see the respective product
information page found at www.intersil.com.
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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
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For information regarding Intersil Corporation and its products, see www.intersil.com
Submit Document Feedback
24
FN6201.4
June 9, 2014
ISL81387, ISL41387
Package Outline Drawing
L40.6x6
40 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE
Rev 3, 10/06
4X 4.5
6.00
36X 0.50
A
B
31
6
PIN 1
INDEX AREA
6
PIN #1 INDEX AREA
40
30
1
6.00
4 . 10 ± 0 . 15
21
10
0.15
(4X)
11
20
0.10 M C A B
TOP VIEW
40X 0 . 4 ± 0 . 1
4 0 . 23 +0 . 07 / -0 . 05
BOTTOM VIEW
SEE DETAIL "X"
0.10 C
0 . 90 ± 0 . 1
( 5 . 8 TYP )
(
C
BASE PLANE
SEATING PLANE
0.08 C
SIDE VIEW
4 . 10 )
( 36X 0 . 5 )
C
0 . 2 REF
5
( 40X 0 . 23 )
0 . 00 MIN.
0 . 05 MAX.
( 40X 0 . 6 )
DETAIL "X"
TYPICAL RECOMMENDED LAND PATTERN
NOTES:
1. Dimensions are in millimeters.
Dimensions in ( ) for Reference Only.
2. Dimensioning and tolerancing conform to AMSE Y14.5m-1994.
3. Unless otherwise specified, tolerance : Decimal ± 0.05
4. Dimension b applies to the metallized terminal and is measured
between 0.15mm and 0.30mm from the terminal tip.
5. Tiebar shown (if present) is a non-functional feature.
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.
Submit Document Feedback
25
FN6201.4
June 9, 2014
ISL81387, ISL41387
Package Outline Drawing
M20.3
20 LEAD WIDE BODY SMALL OUTLINE PLASTIC PACKAGE (SOIC)
Rev 3, 2/11
20
INDEX
AREA
7.60
7.40
1
2
10.65
10.00
0.25 (0.10) M B M
3
3
TOP VIEW
SEATING PLANE
2
13.00
12.60
2.65
2.35
5
0.40
0.75
1.27
BSC
0.49
0.35
7
0.25 (0.10) M
0.25
0.30
MAX
C A M B S
1.27
x 45°
8°
MAX
0.10 (0.004)
SIDE VIEW
DETAIL "X"
0.32
0.23
NOTES:
1. Dimensioning and tolerancing per ASME Y14.5M-1994.
(0.60)
1.27 BSC
2. Dimension 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.
20
(2.00)
3. Dimension does not include interlead lash or protrusions. Interlead
flash and protrusions shall not exceed 0.25mm (0.010 inch) per side.
4. The chamfer on the body is optional. If it is not present, a visual
index feature must be located within the crosshatched area.
(9.40mm)
5. Dimension is the length of terminal for soldering to a substrate.
6. Terminal numbers are shown for reference only.
7. The lead width as measured 0.36mm (0.14 inch) or greater above
the seating plane, shall not exceed a maximum value of 0.61mm
(0.024 inch)
8. Controlling dimension: MILLIMETER.
1
2
3
9. Dimensions in ( ) for reference only.
TYPICAL RECOMMENDED LAND PATTERN
Submit Document Feedback
26
10. JEDEC reference drawing number: MS-013-AC.
FN6201.4
June 9, 2014
ISL81387, ISL41387
Shrink Small Outline Plastic Packages (SSOP)
N
INDEX
AREA
H
0.25(0.010) M
M20.209
B M
(JEDEC MO-150-AE ISSUE B)
20 LEAD SHRINK SMALL OUTLINE PLASTIC PACKAGE
E
1
2
3
0.25
0.010
SEATING PLANE
-A-
INCHES
GAUGE
PLANE
-B-
A
D
-C-

e
A2
A1
B
0.25(0.010) M
L
C
0.10(0.004)
C A M
B S
SYMBOL
MIN
MAX
A
0.068
0.078
1.73
1.99
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
NOTES
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
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
8 deg.
0 deg.

1. Symbols are defined in the “MO Series Symbol List” in Section 2.2
of Publication Number 95.
MAX
A1
N
NOTES:
MILLIMETERS
MIN
20
0 deg.
6
20
7
8 deg.
Rev. 3 11/02
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.
Submit Document Feedback
27
FN6201.4
June 9, 2014
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