MAX13485EELA+ [MAXIM]
Line Transceiver, 1 Func, 1 Driver, 1 Rcvr, BICMOS, 2 X 2 MM, 0.80 MM HEIGHT, LEAD FREE, MICRO DFN-8;
| 型号： | MAX13485EELA+ |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Line Transceiver, 1 Func, 1 Driver, 1 Rcvr, BICMOS, 2 X 2 MM, 0.80 MM HEIGHT, LEAD FREE, MICRO DFN-8 驱动 信息通信管理 接口集成电路 驱动器 |
| 文件： | 总16页 (文件大小：254K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-0742; Rev 0; 1/07
Half-Duplex RS-485/RS-422 Transceivers in µDFN
5/MAX13486E
General Description
Features
The MAX13485E/MAX13486E +5V, half-duplex, 15ꢀV
ESD-protected RS-485 transceivers feature one driver
and one receiver. These devices include fail-safe circuitry,
guaranteeing a logic-high receiver output when receiver
inputs are open or shorted. The receiver outputs a logic-
high if all transmitters on a terminated bus are disabled
(high impedance). The MAX13485E/MAX13486E include
a hot-swap capability to eliminate false transitions on the
bus during power-up or live-insertion.
♦ +5V Operation
♦ True Fail-Safe Receiver While Maintaining
EIA/TIA-485 Compatibility
♦ Hot-Swappable for Telecom Applications
♦ Enhanced Slew-Rate Limiting Facilitates Error-
Free Data Transmission (MAX13485E)
♦ High-Speed Version (MAX13486E) Allows for
Transmission Speeds Up to 16Mbps
The MAX13485E features reduced slew-rate drivers
that minimize EMI and reduce reflections caused by
improperly terminated cables, allowing error-free trans-
mission up to 500ꢀbps. The MAX13486E driver slew
rate is not limited, allowing transmit speeds up to
16Mbps.
♦ Extended ESD Protection for RS-485/RS-422 I/O
Pins 15kV Using Human Body Model
♦ 1/4 Unit Load, Allowing Up to 128 Transceivers on
the Bus
♦ Available in Space-Saving 8-Pin μDFN or Industry
Standard 8-Pin SO Packages
The MAX13485E/MAX13486E feature a 1/4-unit load
receiver input impedance, allowing up to 128 transceivers
on the bus. These devices are intended for half-duplex
communications. All driver outputs are protected to 15ꢀV
ESD using the Human Body Model. The MAX13485E/
MAX13486E are available in 8-pin SO and space-saving
8-pin µDFN pacꢀages. The devices operate over the
extended -40°C to +85°C temperature range.
Ordering Information/
Selector Guide
PIN-
PACKAGE
SLEW-RATE
LIMITED
PKG
CODE
PART
MAX13485EELA+T 8 µDFN
MAX13485EESA+ 8 SO
MAX13486EELA+T 8 µDFN
MAX13486EESA+ 8 SO
+Denotes a lead-free pacꢀage.
Yes
Yes
No
L822-1
S8-2
Applications
L822-1
S8-2
Utility Meters
No
Industrial Controls
Industrial Motor Drives
Automated HVAC Systems
Note: All devices are specified over the -40°C to +85°C operating
temperature range.
Pin Configurations
TOP VIEW
V
B
7
A
6
GND
5
CC
8
MAX13485E
MAX13486E
DE
+
0.1μF
+
1
2
3
4
8
1
2
V
RO
RE
DE
DI
CC
D
R
DI
7
B
A
B
A
RO
RE
DE
DI
Rt
Rt
DFN
3
4
6
5
+
D
RO
R
RO
RE
DE
DI
1
2
3
4
R
8
7
6
5
V
B
A
CC
GND
SO
MAX13485E
MAX13486E
RE
D
GND
SO
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Half-Duplex RS-485/RS-422 Transceivers in µDFN
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND.)
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
V
CC
........................................................................................+6V
DE, RE, DI.................................................................-0.3V to +6V
A, B ..............................................................................-8V to 13V
Short-Circuit Duration (RO, A, B) to GND ..................Continuous
Continuous Power Dissipation (T = +70°C)
A
8-Pin SO (derate 5.9mW/°C above +70°C)..................471mW
8-Pin µDFN (derate 4.8mW/°C above +70°C) ..........380.6mW
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
CC
= +5V 5ꢁ, T = T
to T
, unless otherwise noted. Typical values are at V
= +5V and T = +25°C.) (Notes 1, 2)
CC A
A
MIN
MAX
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DRIVER
R
R
= 100Ω, Figure 1
2.0
1.5
V
V
DIFF
DIFF
CC
CC
Differential Driver Output
V
= 54Ω, Figure 1
V
OD
No load
Change in Magnitude of
Differential Output Voltage
5/MAX13486E
ΔV
R
R
R
= 100Ω or 54Ω, Figure 1 (Note 3)
= 100Ω or 54Ω, Figure 1
0.2
3
V
V
V
OD
DIFF
DIFF
DIFF
Driver Common-Mode Output
Voltage
V
CC
/ 2
V
OC
Change in Magnitude of
Common-Mode Voltage
ΔV
= 100Ω or 54Ω, Figure 1 (Note 3)
0.2
OC
Input-High Voltage
Input-Low Voltage
Input Current
V
DI, DE, RE
DI, DE, RE
DI, DE, RE
2.0
V
V
IH
V
0.8
1
IL
I
IN
µA
0V < V
< +12V
< 0V
+50
-250
20
+250
-50
OUT
Driver Short-Circuit Output
Current (Note 4)
I
mA
mA
OSD
-7V < V
OUT
(V
CC
- 1V) < V
< +12V
OUT
Driver Short-Circuit Foldbacꢀ
Output Current Note 3)
I
OSDF
-7V < V
< 0V
-20
OUT
RECEIVER
V
V
= +12V
= -7V
250
IN
IN
DE = GND, V
or +5V
= GND
CC
Input Current (A and B)
I
µA
A, B
-200
-200
Receiver-Differential-Threshold
Voltage
V
-7V < V
< +12V
CM
-50
mV
mV
V
TH
Receiver Input Hysteresis
ΔV
V
+ V = 0V
25
TH
A
B
V
-
CC
Output-High Voltage
V
I = -1.6mA, V - V > V
O A B TH
OH
1.5
2
_______________________________________________________________________________________
Half-Duplex RS-485/RS-422 Transceivers in µDFN
ELECTRICAL CHARACTERISTICS (continued)
5/MAX13486E
(V
CC
= +5V 5ꢁ, T = T
to T
, unless otherwise noted. Typical values are at V
= +5V and T = +25°C.) (Notes 1, 2)
CC A
A
MIN
MAX
PARAMETER
SYMBOL
CONDITIONS
= 1mA, V - V < -V
MIN
TYP
MAX
UNITS
Output-Low Voltage
V
I
0.4
V
OL
O
A
B
TH
Tri-State Output Current at
Receiver
I
0V < V < V
CC
1
µA
ꢀΩ
mA
OZR
O
Receiver Input Resistance
R
-7V < V
< +12V
48
7
IN
CM
RO
Receiver-Output Short-Circuit
Current
I
0V < V
< V
95
OSR
CC
POWER SUPPLY
Supply Voltage
V
4.75
5.25
4.5
10
V
CC
Supply Current
I
DE = 1, RE = 0, no load
DE = 0, RE = 1
mA
µA
CC
Shutdown Supply Current
ESD PROTECTION
I
SHDN
Air Gap Discharge IEC61000-4-2
(MAX13485E)
15
ESD Protection (A, B)
ꢀV
ꢀV
Human Body Model
Human Body Model
15
2
ESD Protection (All Other Pins)
SWITCHING CHARACTERISTICS—MAX13485E
(V
CC
= +5V 5ꢁ, T = T
to T
, unless otherwise noted. Typical values are at V
= +5V and T = +25°C.) (Note 1)
CC A
A
MIN
MAX
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DRIVER
t
t
200
200
250
250
1000
1000
900
DPLH
DPHL
Driver Propagation Delay
R
R
R
= 54Ω, C = 50pF, Figures 2 and 3
ns
ns
ns
DIFF
DIFF
DIFF
L
t
t
HL
Driver-Differential Output Rise or
Fall Time
= 54Ω, C = 50pF, Figures 2 and 3
L
900
LH
Driver-Differential Output Sꢀew
t
= 54Ω, C = 50pF, Figures 2 and 3
140
DSKEW
L
|t
- t
|
DPLH DPHL
Maximum Data Rate
500
ꢀbps
ns
Driver Enable to Output High
Driver Enable to Output Low
Driver Disable Time from High
Driver Disable Time from Low
t
Figures 4 and 5
Figures 4 and 5
Figures 4 and 5
Figures 4 and 5
2500
2500
100
DZH
t
ns
DZL
t
ns
DHZ
t
100
ns
DLZ
Driver Enable from Shutdown to
Output High
t
Figures 4 and 5
Figures 4 and 5
5500
ns
DZH(SHDN)
Driver Enable from Shutdown to
Output Low
t
5500
700
ns
ns
DZL(SHDN)
Time to Shutdown
t
50
340
SHDN
RECEIVER
t
80
80
13
RPLH
RPHL
Receiver Propagation Delay
C = 15pF, Figures 6 and 7
ns
L
t
Receiver Output Sꢀew
Maximum Data Rate
t
C = 15pF, Figure 7
L
ns
RSKEW
500
ꢀbps
_______________________________________________________________________________________
3
Half-Duplex RS-485/RS-422 Transceivers in µDFN
SWITCHING CHARACTERISTICS—MAX13485E (continued)
(V
CC
= +5V 5ꢁ, T = T
to T
, unless otherwise noted. Typical values are at V
= +5V and T = +25°C.) (Note 1)
CC A
A
MIN
MAX
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
50
UNITS
ns
Receiver Enable to Output High
Receiver Enable to Output Low
t
Figure 8
Figure 8
Figure 8
Figure 8
RZH
t
50
ns
RZL
Receiver Disable Time from High
Receiver Disable Time from Low
t
50
ns
RHZ
t
50
ns
RLZ
Receiver Enable from Shutdown
to Output High
t
Figure 8
Figure 8
2200
ns
RZH(SHDN)
Receiver Enable from Shutdown
to Output Low
t
2200
700
ns
ns
RZL(SHDN)
Time to Shutdown
t
50
340
SHDN
SWITCHING CHARACTERISTICS—MAX13486E
(V
CC
= +5V 5ꢁ, T = T
to T
, unless otherwise noted. Typical values are at V
= +5V and T = +25°C.) (Note 1)
CC A
A
MIN
MAX
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
5/MAX13486E
DRIVER
t
t
50
50
15
15
DPLH
DPHL
Driver Propagation Delay
R
R
R
= 54Ω, C = 50pF, Figures 2 and 3
ns
ns
ns
DIFF
DIFF
DIFF
L
t
t
HL
Driver Differential Output Rise or
Fall Time
= 54Ω, C = 50pF, Figures 2 and 3
L
LH
Differential Driver Output Sꢀew
t
= 54Ω, C = 50pF, Figures 2 and 3
8
DSKEW
L
|t
- t
|
DPLH DPHL
Maximum Data Rate
16
Mbps
ns
Driver Enable to Output High
Driver Enable to Output Low
Driver Disable Time from High
Driver Disable Time from Low
t
Figures 4 and 5
Figures 4 and 5
Figures 4 and 5
Figures 4 and 5
50
50
50
50
DZH
t
ns
DZL
t
ns
DHZ
t
ns
DLZ
Driver Enable from Shutdown to
Output High
t
Figures 4 and 5
Figures 4 and 5
2200
ns
DZH(SHDN)
Driver Enable from Shutdown to
Output Low
t
2200
700
ns
ns
DZL(SHDN)
Time to Shutdown
t
50
16
340
SHDN
RECEIVER
t
80
80
13
RPLH
RPHL
Receiver Propagation Delay
C = 15pF, Figures 6 and 7
L
ns
t
Receiver Output Sꢀew
Maximum Data Rate
t
C = 15pF, Figure 7
L
ns
RSKEW
Mbps
4
_______________________________________________________________________________________
Half-Duplex RS-485/RS-422 Transceivers in µDFN
5/MAX13486E
SWITCHING CHARACTERISTICS—MAX13486E (continued)
(V
CC
= +5V 5ꢁ, T = T
to T
, unless otherwise noted. Typical values are at V
= +5V and T = +25°C.) (Note 1)
CC A
A
MIN
MAX
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
50
UNITS
ns
Receiver Enable to Output High
Receiver Enable to Output Low
t
Figure 8
Figure 8
Figure 8
Figure 8
RZH
t
50
ns
RZL
Receiver Disable Time from High
Receiver Disable Time from Low
t
50
ns
RHZ
t
50
ns
RLZ
Receiver Enable from Shutdown
to Output High
t
Figure 8
Figure 8
2200
ns
RZH(SHDN)
Receiver Enable from Shutdown
to Output Low
t
2200
700
ns
ns
RZL(SHDN)
Time to Shutdown
t
50
340
SHDN
Note 1: µDFN devices production tested at +25°C. Overtemperature limits are generated by design.
Note 2: All currents into the device are positive. All currents out of the device are negative. All voltages referred to device ground,
unless otherwise noted.
Note 3: ΔV
and ΔV
are the changes in V
and V
when the DI input changes states.
OC
OD
OC
OD
Note 4: The short-circuit output current applied to peaꢀ current just prior to foldbacꢀ current limiting. The short-circuit foldbacꢀ
output current applies during current limiting to allow a recovery from bus contention.
Typical Operating Characteristics
(V
CC
= +5V, T = +25°C, unless otherwise noted.)
A
OUTPUT CURRENT vs. RECEIVER
OUTPUT HIGH VOLTAGE
OUTPUT CURRENT vs. RECEIVER
OUTPUT LOW VOLTAGE
SUPPLY CURRENT vs. TEMPERATURE
60
50
40
30
20
10
0
35
28
21
14
7
4.0
NO LOAD
3.8
3.6
3.4
3.2
3.0
0
0
1
2
3
4
5
0
1
2
3
4
5
-40
-15
10
35
60
85
OUTPUT LOW VOLTAGE (V)
OUTPUT HIGH VOLTAGE (V)
TEMPERATURE (°C)
_______________________________________________________________________________________
5
Half-Duplex RS-485/RS-422 Transceivers in µDFN
Typical Operating Characteristics (continued)
(V
CC
= +5V, T = +25°C, unless otherwise noted.)
A
RECEIVER OUTPUT HIGH
VOLTAGE vs. TEMPERATURE
0.5
RECEIVER OUTPUT LOW
VOLTAGE vs. TEMPERATURE
DIFFERENTIAL OUPUT CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
80
60
40
20
0
5.4
5.2
5.0
4.8
4.6
4.4
4.2
4.0
I
= 1mA
I
= 1mA
O
O
0.4
0.3
0.2
0.1
0
-40
-15
10
35
60
85
0
1
2
3
4
5
-40
-15
10
35
60
85
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
TEMPERATURE (°C)
OUTPUT CURRENT vs. TRANSMITTER
OUTPUT HIGH VOLTAGE
DRIVER-DIFFERENTIAL OUTPUT
VOLTAGE vs. TEMPERATURE
OUTPUT CURRENT vs. TRANSMITTER
OUTPUT LOW VOLTAGE
120
100
80
60
40
20
0
3.0
2.5
2.0
1.5
1.0
0.5
0
120
100
80
60
40
20
0
R
DIFF
= 54Ω
5/MAX13486E
-40
-15
10
35
60
85
-7 -6 -5 -4 -3 -2 -1
0
1
2
3
4
5
0
2
4
6
8
10
12
TEMPERATURE (°C)
OUTPUT HIGH VOLTAGE (V)
OUTPUT LOW VOLTAGE (V)
SHUTDOWN CURRENT
vs. TEMPERATURE
DRIVER PROPAGATION
vs. TEMPERATURE (MAX13485E)
DRIVER PROPAGATION DELAY
vs. TEMPERATURE (MAX13486E)
10
9
8
7
6
5
4
3
2
1
0
600
550
500
450
400
350
300
30
25
20
15
10
5
t
DPLH
t
DPHL
t
DPLH
t
DPHL
0
-40
-15
10
35
60
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
6
_______________________________________________________________________________________
Half-Duplex RS-485/RS-422 Transceivers in µDFN
5/MAX13486E
Typical Operating Characteristics (continued)
(V
CC
= +5V, T = +25°C, unless otherwise noted.)
A
RECEIVER PROPAGATION
vs. TEMPERATURE (MAX13485E)
RECEIVER PROPAGATION
vs. TEMPERATURE (MAX13486E)
DRIVER PROPAGATION (500kbps)
(MAX13485E)
MAX13485/86E toc15
80
40
DI
2V/div
60
40
20
0
30
20
10
0
t
RPHL
t
RPLH
t
RPHL
A-B
5V/div
t
RPLH
-40
-15
10
35
60
85
-40
-15
10
35
60
85
400ns/div
TEMPERATURE (°C)
TEMPERATURE (°C)
DRIVER PROPAGATION (16Mbps)
(MAX13486E)
RECEIVER PROPAGATION (16Mbps)
(MAX13486E)
MAX13485/86E toc16
MAX13485/86E toc17
B
DI
2V/div
2V/div
A
2V/div
A-B
RO
5V/div
2V/div
10ns/div
10ns/div
_______________________________________________________________________________________
7
Half-Duplex RS-485/RS-422 Transceivers in µDFN
Test Circuits and Waveforms
A
5V
DE
R
DIFF
DIFF
2
A
B
DI
V
ID
R
DIFF
C
L
V
OD
C
L
R
V
OC
2
B
Figure 2. Driver Timing Test Circuit
Figure 1. Driver DC Test Load
f = 1MHz, t ≤ 3ns, t ≤ 3ns
LH
HL
V
CC
1.5V
DI
1.5V
5/MAX13486E
0
1/2 V
O
t
DPHL
t
DPLH
B
A
1/2 V
O
V
O
V
= V(A) - V(B)
DIFF
V
O
90%
90%
V
DIFF
0
10%
10%
-V
O
t
t
LH
HL
t
= |t
- t
|
DSKEW
DPLH DPHL
Figure 3. Driver Propagation Delays
8
_______________________________________________________________________________________
Half-Duplex RS-485/RS-422 Transceivers in µDFN
5/MAX13486E
Test Circuits and Waveforms (continued)
V
CC
DE
1.5V
1.5V
0
t
t
,t
DLZ
DZL(SHDN) DZL
A, B
V
+ 0.5V
+ 0.5V
OL
2.3V
2.3V
OUTPUT NORMALLY LOW
OUTPUT NORMALLY HIGH
V
OL
A, B
0
V
OH
t
,t
t
DZH(SHDN) DZH
DHZ
Figure 4. Driver Enable and Disable Times
V
CC
S1
S2
B
A
500Ω
OUTPUT
UNDER TEST
RECEIVER
OUTPUT
R
V
ID
ATE
C
L
Figure 5. Driver-Enable and -Disable-Timing Test Load
Figure 6. Receiver Propagation Delay Test Circuit
f = 1MHz, t ≤ 3ns, t ≤ 3ns
LH
HL
A
B
1V
-1V
t
t
RPHL
RPLH
V
V
OH
RO
1.5V
1.5V
t
= |t
- t
|
OL
RSKEW
RPHL RPLH
Figure 7. Receiver Propagation Delays
_______________________________________________________________________________________
9
Half-Duplex RS-485/RS-422 Transceivers in µDFN
Pin Description
PIN
NAME
FUNCTION
1
RO
Receiver Output
Receiver Output Enable. Drive RE low to enable RO. RO is high impedance when RE is high. Drive
RE high and DE low to enter low-power shutdown mode. RE is a hot-swap input (see the Hot-Swap
Capability section for more details).
2
RE
Driver Output Enable. Drive DE high to enable the driver outputs. These outputs are high-impedance
when DE is low. Drive RE high and DE low to enter low-power shutdown mode. DE is a hot-swap input
(see the Hot-Swap Capability section for more details).
3
4
DE
DI
Driver Input. Drive DI low to force noninverting output low and inverting output high. Drive DI high to
force noninverting output high and inverting output low (see the Function Tables).
5
6
7
8
GND
A
Ground
Noninverting Receiver Input and Noninverting Driver Output
Inverting Receiver Input and Inverting Driver Output
B
V
Positive Supply, V
= +5V 5ꢁ. Bypass V
to GND with a 0.1µF capacitor.
CC
CC
CC
Function Tables
5/MAX13486E
TRANSMITTING
OUTPUT
INPUT
RE
X
DE
1
DI
1
B
0
1
A
1
0
X
1
0
0
0
X
X
HIGH IMPEDANCE HIGH IMPEDANCE
SHUTDOWN
1
0
RECEIVING
INPUT
OUTPUT
RE
DE
A-B
> -50mV
< -200mV
OPEN/SHORT
X
RO
0
0
0
1
1
X
X
X
1
0
1
0
1
HIGH IMPEDANCE
SHUTDOWN
X
X = Don’t care, shutdown mode, driver, and receiver outputs
are in high impedance.
10 ______________________________________________________________________
Half-Duplex RS-485/RS-422 Transceivers in µDFN
5/MAX13486E
Test Circuits and Waveforms (continued)
S1
+1V
S3
V
CC
1kΩ
-1V
V
ID
CL
15pF
S2
GENERATOR
50Ω
S1 CLOSED
S2 OPEN
S3 = -1V
S1 OPEN
S2 CLOSED
S3 = +1V
V
CC
V
CC
V
/2
V
/2
CC
CC
RE
RE
0
0
t
, t
RZH RZH(SHDN)
t
, t
RZL RZL(SHDN)
V
OH
V
CC
RO
V
/2
OH
(V + V )/2
OL
CC
RO
0
V
OL
S1 CLOSED
S1 OPEN
S2 OPEN
S3 = -1V
S2 CLOSED
S3 = +1V
V
0
V
CC
CC
V
CC
/2
V
CC
/2
RE
0
RE
t
RLZ
t
RHZ
V
CC
V
OH
RO
0.25V
RO
V
OL
0.25V
0
Figure 8. Receiver Enable and Disable Times
__________________________________________________________________________
Half-Duplex RS-485/RS-422 Transceivers in µDFN
Detailed Description
The MAX13485E/MAX13486E half-duplex, high-speed
V
CC
transceivers for RS-485/RS-422 communication contain
one driver and one receiver. These devices feature fail-
safe circuitry that guarantees a logic-high receiver out-
put when receiver inputs are open or shorted, or when
they are connected to a terminated transmission line
with all drivers disabled (see the Fail-Safe section). The
MAX13485E/MAX13486E also feature a hot-swap capa-
bility allowing line insertion without erroneous data
transfer (see the Hot-Swap Capability section). The
MAX13485E features reduced slew-rate drivers that
minimize EMI and reduce reflections caused by
improperly terminated cables, allowing error-free trans-
mission up to 500ꢀbps. The MAX13486E driver slew
rate is not limited, maꢀing transmit speeds up to
16Mbps possible.
10μs
TIMER
SR LATCH
TIMER
5kΩ
DE
DE
(HOT SWAP)
Fail-Safe
The MAX13485E/MAX13486E guarantee a logic-high
receiver output when the receiver inputs are shorted or
open, or when they are connected to a terminated
transmission line with all drivers disabled. This is done by
setting the receiver input threshold between -50mV and
-200mV. If the differential receiver input voltage (A - B) is
greater than or equal to -50mV, RO is logic-high. If (A - B)
is less than or equal to -200mV, RO is logic-low. In the
case of a terminated bus with all transmitters disabled,
the receiver’s differential input voltage is pulled to 0V by
the termination. With the receiver thresholds of the
MAX13485E/MAX13486E, this results is a logic-high with
a 50mV minimum noise margin. Unliꢀe previous fail-safe
devices, the -50mV to -200mV threshold complies with
the 200mV EIA/TIA-485 standard.
100μA
500μA
M1
M2
5/MAX13486E
Figure 9. Simplified Structure of the Driver Enable Pin (DE)
When V
rises, an internal pulldown circuit holds DE
CC
low and RE high. After the initial power-up sequence,
the pulldown circuit becomes transparent, resetting the
hot-swap tolerable input.
Hot-Swap Input Circuitry
The enable inputs feature hot-swap capability. At the
input there are two nMOS devices, M1 and M2 (Figure
Hot-Swap Capability
9). When V
ramps from zero, an internal 7µs timer
CC
Hot-Swap Inputs
When circuit boards are inserted into a hot or powered
bacꢀplane, differential disturbances to the data bus
can lead to data errors. Upon initial circuit-board inser-
tion, the data communication processor undergoes its
own power-up sequence. During this period, the
processor’s logic-output drivers are high impedance
and are unable to drive the DE and RE inputs of these
devices to a defined logic level. Leaꢀage currents up to
10µA from the high impedance state of the proces-
sor’s logic drivers could cause standard CMOS enable
inputs of a transceiver to drift to an incorrect logic level.
Additionally, parasitic circuit-board capacitance could
turns on M2 and sets the SR latch, which also turns on
M1. Transistors M2, a 1.5mA current sinꢀ, and M1, a
500µA current sinꢀ, pull DE to GND through a 5ꢀΩ
resistor. M2 is designed to pull DE to the disabled state
against an external parasitic capacitance up to 100pF
that can drive DE high. After 7µs, the timer deactivates
M2 while M1 remains on, holding DE low against tri-
state leaꢀages that can drive DE high. M1 remains on
until an external source overcomes the required input
current. At this time, the SR latch resets and M1 turns
off. When M1 turns off, DE reverts to a standard high-
impedance CMOS input. Whenever V
1V, the hot-swap input is reset.
drops below
CC
cause coupling of V
or GND to the enable inputs.
CC
For RE there is a complementary circuit employing two
pMOS devices pulling RE to V
Without the hot-swap capability, these factors could
improperly enable the transceiver’s driver or receiver.
.
CC
12 ______________________________________________________________________________________
Half-Duplex RS-485/RS-422 Transceivers in µDFN
5/MAX13486E
R
R
C
R
D
R
D
C
1MΩ
50MΩ TO 100MΩ
1500Ω
330Ω
DISCHARGE
RESISTANCE
CHARGE-CURRENT
LIMIT RESISTOR
DISCHARGE
RESISTANCE
CHARGE-CURRENT
LIMIT RESISTOR
HIGH-
VOLTAGE
DC
DEVICE
UNDER
TEST
HIGH-
VOLTAGE
DC
DEVICE
UNDER
TEST
C
s
150pF
STORAGE
CAPACITOR
C
s
100pF
STORAGE
CAPACITOR
SOURCE
SOURCE
Figure 10c. IEC 61000-4-2 ESD Test Model
Figure 10a. Human Body ESD Test Model
I
100%
90%
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
I
100%
90%
I
P
r
AMPS
36.8%
10%
0
10%
TIME
0
t = 0.7ns TO 1ns
t
r
RL
t
30ns
t
DL
60ns
CURRENT WAVEFORM
Figure 10d. IEC 61000-4-2 ESD Generator Current Waveform
Figure 10b. Human Body Current Waveform
ESD Test Conditions
ESD performance depends on a variety of conditions.
Contact Maxim for a reliability report that documents
test setup, test methodology, and test results.
+15V ESD Protection
As with all Maxim devices, ESD-protection structures
are incorporated on all pins to protect against electro-
static discharges encountered during handling and
assembly. The driver outputs and receiver inputs of the
MAX13485E/MAX13486E have extra protection against
static electricity. Maxim’s engineers have developed
state-of-the-art structures to protect these pins against
ESD of 15ꢀV without damage. The ESD structures
withstand high ESD in all states: normal operation, shut-
down, and powered down. After an ESD event, the
MAX13485E/MAX13486E ꢀeep worꢀing without latchup
or damage.
Human Body Model
Figure 10a shows the Human Body Model, and Figure
10b shows the current waveform it generates when dis-
charged into a low impedance. This model consists of
a 100pF capacitor charged to the ESD voltage of inter-
est, which is then discharged into the test device
through a 1.5ꢀΩ resistor.
IEC 61000-4-2
The IEC 61000-4-2 standard covers ESD testing and
performance of finished equipment. However, it does
not specifically refer to integrated circuits. The
MAX13485E/MAX13486E help equipment designs to
meet IEC 61000-4-2, without the need for additional
ESD-protection components.
ESD protection can be tested in various ways. The trans-
mitter outputs and receiver inputs of the MAX13485E/
MAX13486E are characterized for protection to the follow-
ing limits:
•
•
15ꢀV using the Human Body Model
15ꢀV using the Air Gap Discharge Method specified
in IEC 61000-4-2 (MAX13485E only)
The major difference between tests done using the
Human Body Model and IEC 61000-4-2 is higher peaꢀ
current in IEC 61000-4-2 because series resistance is
lower in the IEC 61000-4-2 model. Hence, the ESD
______________________________________________________________________________________ 13
Half-Duplex RS-485/RS-422 Transceivers in µDFN
DI
D
DI
DE
D
R
R
t
t
DE
RO
RE
RO
RE
R
R
R
R
MAX13485E
MAX13486E
D
D
DI
DE
RO RE
DI
DE
RO RE
Figure 11. Typical Half-Duplex RS-485 Networꢀ
withstand voltage measured to IEC 61000-4-2 is gener-
ally lower than that measured using the Human Body
Model. Figure 10c shows the IEC 61000-4-2 model,
and Figure 10d shows the current waveform for the IEC
61000-4-2 ESD Contact Discharge test.
Low-Power Shutdown Mode
Low-power shutdown mode is initiated by bringing both
RE high and DE low. In shutdown, the devices draw a
maximum of 10µA of supply current.
5/MAX13486E
RE and DE can be driven simultaneously. The devices
are guaranteed not to enter shutdown if RE is high and
DE is low for less than 50ns. If the inputs are in this
state for at least 700ns, the devices are guaranteed to
enter shutdown.
Machine Model
The machine model for ESD tests all pins using a 200pF
storage capacitor and zero discharge resistance.
The objective is to emulate the stress caused when I/O
pins are contacted by handling equipment during test
and assembly. Of course, all pins require this protec-
tion, not just RS-485 inputs and outputs.
Enable times t
and t (see the Switching Character-
ZL
ZH
istics) assume the devices were not in a low-power shut-
down state. Enable times t and t
ZH(SHDN)
ZL(SHDN)
assume the devices were in shutdown state. It taꢀes dri-
vers and receivers longer to become enabled from low-
The air-gap test involves approaching the device with a
charged probe. The contact-discharge method connects
the probe to the device before the probe is energized.
power shutdown mode (t
, t
ZH ZL
) than from
ZH(SHDN) ZL(SHDN)
driver-/receiver-disable mode (t , t ).
Applications Information
Line Length
The RS-485/RS-422 standard covers line lengths up to
4000ft.
128 Transceivers on the Bus
The standard RS-485 receiver input impedance is 12ꢀΩ
(1-unit load), and the standard driver can drive up to
32-unit loads. The MAX13485E/MAX13486E have a 1/4-
unit load receiver input impedance (48ꢀΩ), allowing up
to 128 transceivers to be connected in parallel on one
communication line. Any combination of these devices,
as well as other RS-485 transceivers with a total of 32-
unit loads or fewer, can be connected to the line.
Typical Applications
The MAX13485E/MAX13486E transceivers are
designed for half-duplex, bidirectional data communi-
cations on multipoint bus transmission lines. Figure 11
shows typical networꢀ applications circuits. To mini-
mize reflections, terminate the line at both ends in its
characteristic impedance, and ꢀeep stub lengths off
the main line as short as possible. The slew-rate-limited
MAX13485E is more tolerant of imperfect termination.
Reduced EMI and Reflections
The MAX13485E features reduced slew-rate drivers
that minimize EMI and reduce reflections caused by
improperly terminated cables, allowing error-free data
transmission up to 500ꢀbps.
Chip Information
PROCESS: BiCMOS
14 ______________________________________________________________________________________
Half-Duplex RS-485/RS-422 Transceivers in µDFN
5/MAX13486E
Package Information
(The pacꢀage drawing(s) in this data sheet may not reflect the most current specifications. For the latest pacꢀage outline information,
go to www.maxim-ic.com/packages.)
INCHES
MILLIMETERS
DIM
A
MIN
MAX
0.069
0.010
0.019
0.010
MIN
1.35
0.10
0.35
0.19
MAX
1.75
0.25
0.49
0.25
0.053
0.004
0.014
0.007
N
A1
B
C
e
0.050 BSC
1.27 BSC
E
0.150
0.228
0.016
0.157
0.244
0.050
3.80
5.80
0.40
4.00
6.20
1.27
E
H
H
L
VARIATIONS:
INCHES
1
MILLIMETERS
DIM
D
MIN
MAX
0.197
0.344
0.394
MIN
4.80
8.55
9.80
MAX
5.00
N
8
MS012
AA
TOP VIEW
0.189
0.337
0.386
D
8.75 14
10.00 16
AB
D
AC
D
C
A
B
0∞-8∞
e
A1
L
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, .150" SOIC
APPROVAL
DOCUMENT CONTROL NO.
REV.
1
21-0041
B
1
______________________________________________________________________________________ 15
Half-Duplex RS-485/RS-422 Transceivers in µDFN
Package Information (continued)
(The pacꢀage drawing(s) in this data sheet may not reflect the most current specifications. For the latest pacꢀage outline information,
go to www.maxim-ic.com/packages.)
A
b
D
e
N
XXXX
XXXX
XXXX
SOLDER
MASK
COVERAGE
E
PIN 1
0.10x45∞
L
L1
1
SAMPLE
MARKING
PIN 1
INDEX AREA
A
A
7
(N/2 -1) x e)
C
L
C
L
b
L
L
A
e
e
A2
EVEN TERMINAL
ODD TERMINAL
A1
5/MAX13486E
PACKAGE OUTLINE,
6, 8, 10L uDFN, 2x2x0.80 mm
1
-DRAWING NOT TO SCALE-
21-0164
A
2
COMMON DIMENSIONS
SYMBOL
MIN.
0.70
0.15
0.020
1.95
1.95
0.30
NOM.
MAX.
A
0.75
0.20
0.025
2.00
2.00
0.40
0.80
0.25
0.035
2.05
2.05
0.50
A1
A2
D
-
E
L
L1
0.10 REF.
PACKAGE VARIATIONS
PKG. CODE
L622-1
N
6
e
b
(N/2 -1) x e
0.65 BSC
0.50 BSC
0.40 BSC
0.30±0.05 1.30 REF.
0.25±0.05 1.50 REF.
0.20±0.03 1.60 REF.
L822-1
8
L1022-1
10
PACKAGE OUTLINE,
6, 8, 10L uDFN, 2x2x0.80 mm
2
21-0164
A
-DRAWING NOT TO SCALE-
2
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2007 Maxim Integrated Products
is a registered trademarꢀ of Maxim Integrated Products, Inc.
Boblet
相关型号：
MAX13486EELA+
Line Transceiver, 1 Func, 1 Driver, 1 Rcvr, BICMOS, 2 X 2 MM, 0.80 MM HEIGHT, LEAD FREE, MICRO DFN-8
MAXIM
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