MAX3293_14 [MAXIM]
20Mbps, 3.3V, SOT23 RS-485/RS-422 Transmitters;
| 型号： | MAX3293_14 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 20Mbps, 3.3V, SOT23 RS-485/RS-422 Transmitters |
| 文件： | 总11页 (文件大小：1843K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MAX3293–MAX3295
20Mbps, +3.3V, SOT23 RS-485/
RS-422 Transmitters
General Description
Features
The MAX3293/MAX3294/MAX3295 low-power, high-
speed transmitters for RS-485/RS-422 commu-
nication operate from a single +3.3V power supply.
These devices contain one differential transmitter.
The MAX3295 transmitter operates at data rates up
to 20Mbps, with an output skew of less than 5ns, and
a guaranteed driver propagation delay below 25ns.
The MAX3293 (250kbps) and MAX3294 (2.5Mbps) are
slew-rate limited to minimize EMI and reduce reflections
caused by improperly terminated cables.
● Space-Saving 6-Pin SOT23 Package
● 250kbps/2.5Mbps/20Mbps Data Rates Available
● Operate from a Single +3.3V Supply
● ESD Protection
±9kV–Human Body Model
● Slew-Rate Limited for Errorless Data Transmission
(MAX3293/MAX3294)
● 1µA Low-Current Shutdown Mode
● -7V to +12V Common-Mode Input Voltage Range
The MAX3293/MAX3294/MAX3295 output level is guar-
anteed at +1.5V with a standard 54Ω load, compliant
with RS-485 specifications. The transmitter draws 5mA
of supply current when unloaded, and 1µA in low-power
shutdown mode (DE = GND).
● Current Limiting and Thermal Shutdown for
Driver-Overload Protection
● Hot-Swap Inputs for Telecom Applications
● Automotive Temperature Range (-40°C to +125°C)
Hot-swap circuitry eliminates false transitions on the data
cable during circuit initialization or connection to a live
backplane, and short-circuit current limiting and ther-
mal-shutdown circuitry protect the driver against exces-
sive power dissipation.
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX3293AUT+T
MAX3294AUT+T
MAX3295AUT+T
MAX3295AUT/V+T
-40°C to +125°C 6 SOT23-6
-40°C to +125°C 6 SOT23-6
-40°C to +125°C 6 SOT23-6
-40°C to +125°C 6 SOT23-6
The MAX3293/MAX3294/MAX3295 are offered in a
6-pin SOT23 package, and are specified over the
automotive temperature range.
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
/V denotes automotive-qualified package.
Applications
● RS-485/RS-422 Communications
● Clock Distribution
● Telecom Equipment
● Automotive
● Security Equipment
● Point-of-Sale Equipment
● Industrial Control
Selector Guide
MAXIMUM
DATA RATE
(Mbps)
SLEW-
RATE
LIMITED
TOP
MARK
PART
ABNI or
ABVH
MAX3293AUT+T
MAX3294AUT+T
0.25
2.5
Yes
Yes
Typical Operating Circuit
ABNJ or
ABVI
120Ω
Z
DI
ABNK or
ABVJ
RO
D
R
MAX3295AUT+T
20
20
No
No
Y
DE
MAX3295AUT/V+T
+ACSB
MAX3293
MAX3294
MAX3295
MAX3280E
MAX3281E
MAX3283E
MAX3284E
Pin Configuration appears at end of data sheet.
19-2770; Rev 4; 12/14
MAX3293–MAX3295
20Mbps, +3.3V, SOT23 RS-485/
RS-422 Transmitters
Absolute Maximum Ratings
(All voltages referenced to GND, unless otherwise noted.)
Operating Temperature Ranges
Supply Voltage (V )............................................................+6V
DE, DI......................................................................-0.3V to +6V
Y, Z ........................................................................-7V to +12.5V
MAX32_ _AUT.............................................. -40°C to +125°C
Storage Temperature Range............................ -65°C to +160°C
Junction Temperature .....................................................+160°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow).......................................+260°C
CC
Maximum Continuous Power Dissipation (T = +70°C)
A
SOT23 (derate 8.2mW/°C above +70°C).................654.1mW
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
= +3.3V ±5%, T = T
to T
, unless otherwise noted. Typical values are at V
= +3.3V and T = +25°C.) (Notes 1, 2)
CC
A
MIN
MAX
CC A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
POWER SUPPLY
Supply Voltage
V
3.135
3.300
3.465
5
V
CC
Supply Current in Normal
Operation
I
No load, DI = V
or GND, DE = V
CC
mA
µA
Q
CC
Supply Current in Shutdown Mode
I
No load, DE = GND
1
10
SHDN
DRIVER
R = 50Ω (RS-422),
T ≤ +85°C
,
2.0
1.5
V
V
CC
CC
Figure 1, DE = V
DI = GND or V
A
CC
Differential Driver Output
V
V
OD
R = 27Ω (RS-485),
≤ +85°C
CC
T
A
Change in Magnitude of
Figure 1, R = 27Ω or 50Ω,
DE = V (Note 3)
∆
0.2
+3
V
V
V
VOD
Differential Output Voltage
CC
Driver Common-Mode
Output Voltage
Figure 1, R = 27Ω or 50Ω,
DE = V , DI = V or GND
V
-1
OC
CC
CC
Change in Magnitude of
Common-Mode Voltage
∆V
Figure 1, R = 27Ω or 50Ω (Note 3)
0.2
OC
DRIVER LOGIC
Input High Voltage
Input Low Voltage
Input Current
V
DE, DI
DE, DI
DE, DI
Y, Z
2.0
V
V
IH
V
0.8
+2
IL
I
-2
µA
IN
V
V
= +12V
= -7V
-20
+20
+20
IN
IN
DE = GND,
= GND or
Output Leakage
I
µA
O
V
CC
-20
+3.3V
(V
- 1V) ≤ V
≤ +12V, output high
+25
Driver Short-Circuit Foldback
Output Current
CC
OUT
I
mA
mA
OSFD
-7V ≤ V
0 ≤ V
≤ 1V, output high
-25
OUT
≤ +12V, output low
-250
Driver Short-Circuit
Output Current
OUT
I
OSD
-7V ≤ V
≤ V , output high
+250
OUT
CC
Thermal-Shutdown Threshold
Thermal-Shutdown Hysteresis
ESD Protection
T
160
40
°C
°C
kV
TS
T
TSH
Y, Z
Human Body Model
±9
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MAX3293–MAX3295
20Mbps, +3.3V, SOT23 RS-485/
RS-422 Transmitters
Switching Characteristics (MAX3293)
(V
= +3.3V ±5%, T = +25°C, unless otherwise noted. Typical values are at V
= +3.3V.)
CC
A
CC
PARAMETER
SYMBOL
CONDITIONS
MIN
400
400
400
400
TYP
MAX
1300
1300
1200
1200
UNITS
t
Figures 2, 3; R
= 54Ω,
PLH
DIFF
Driver Propagation Delay
ns
C = 50pF
L
t
PHL
t
Driver Differential Output Rise
or Fall Time
Figures 2, 3; R
= 54Ω,
R
DIFF
ns
ns
C = 50pF
L
t
F
Figures 2, 3; R
= 54Ω, C = 50pF,
L
DIFF
Driver-Output Skew
t
-400
+400
+100
SKEW
t
= | t
- t
| (Note 5)
SKEW
PLH PHL
Differential Driver-Output Skew
Maximum Data Rate
t
Figures 2, 3; R
Figures 2, 3; R
= 54Ω, C = 50pF
-100
250
ns
DSKEW
DIFF
L
= 54Ω, C = 50pF
kbps
DIFF
L
Figures 4, 5; S2 closed, R = 500Ω,
L
Driver Enable to Output High
Driver Enable to Output Low
Driver Disable Time from Low
Driver Disable Time from High
t
2000
2000
1000
1000
900
ns
ns
ns
ns
ns
ZH
C = 100pF
L
Figures 4, 5; S1 closed, R = 500Ω,
L
t
ZL
LZ
HZ
C = 100pF
L
Figures 4, 5; S1 closed, R = 500Ω,
L
t
C = 100pF
L
Figures 4, 5; S2 closed, R = 500Ω,
L
t
C = 100pF
L
Device-to-Device Propagation
Delay Matching
Same power supply, maximum temperature
difference between devices = +30°C (Note 5)
Switching Characteristics (MAX3294)
(V
= +3.3V ±5%, T = +25°C, unless otherwise noted. Typical values are at V
= +3.3V.)
CC
A
CC
PARAMETER
SYMBOL
CONDITIONS
MIN
24
TYP
MAX
70
UNITS
t
Figures 2, 3; R
= 54Ω,
PLH
DIFF
Driver Propagation Delay
ns
C = 50pF
L
t
24
70
PHL
t
10
70
Figures 2, 3; R
= 54Ω,
Driver Differential Output Rise or
Fall Time
R
DIFF
ns
ns
C = 50pF
L
t
10
70
F
Figures 2, 3; R
= 54Ω, C = 50pF,
L
| (Note 5)
DIFF
Driver-Output Skew
t
-40
+40
+6
SKEW
t
= | t
- t
SKEW
PLH PHL
Differential Driver-Output Skew
Maximum Data Rate
t
Figures 2, 3; R
Figures 2, 3; R
= 54Ω, C = 50pF
-6
ns
Mbps
ns
DSKEW
DIFF
L
= 54Ω, C = 50pF
2.5
DIFF
L
Figures 4, 5; S2 closed, R = 500Ω,
L
Driver Enable to Output High
t
400
400
100
100
46
ZH
C = 100pF
L
Figures 4, 5; S1 closed, R = 500Ω,
L
Driver Enable to Output Low
Driver Disable Time from Low
Driver Disable Time from High
t
ns
ns
ns
ns
ZL
LZ
HZ
C = 100pF
L
Figures 4, 5; S1 closed, R = 500Ω,
L
t
C = 100pF
L
Figures 4, 5; S2 closed, R = 500Ω,
C = 100pF
L
L
t
Same power supply, maximum temperature
difference between devices = +30°C (Note 5)
Device-to-Device Propagation
Delay Matching
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MAX3293–MAX3295
20Mbps, +3.3V, SOT23 RS-485/
RS-422 Transmitters
Switching Characteristics (MAX3295)
(V
= +3.3V ±5%, T = +25°C, unless otherwise noted. Typical values are at V
= +3.3V.)
CC
A
CC
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
25
UNITS
t
t
PLH
PHL
Driver Propagation Delay
Figures 2, 3; R
Figures 2, 3;
= 54Ω, CL = 50
pF
ns
DIFF
25
T
T
T
T
= -40°C to +125°C
< +85°C
18.5
15
A
A
A
A
t
R
Driver Differential Output Rise
or Fall Time
R
= 54Ω,
ns
DIFF
= -40°C to +125°C
< +85°C
18.5
15
C = 50pF
L
t
F
Figures 2, 3; R
= 54Ω, C = 50pF,
L
|
DIFF
- t
Driver-Output Skew
t
5
5
ns
ns
SKEW
t
= | t
SKEW
PLH PHL
Differential Driver-Output Skew
t
Figures 2, 3; R
Figures 2, 3; R
= 54Ω, C = 50pF
L
DSKEW
DIFF
= 54Ω, C = 50pF,
DIFF
L
20
16
T
≤ +85°C
Maximum Data Rate
Mbps
A
Figures 2, 3; R
= 54Ω, C = 50pF
L
DIFF
Figures 4, 5; S2 closed, R = 500Ω,
L
Driver Enable to Output High
Driver Enable to Output Low
Driver Disable Time from Low
Driver Disable Time from High
t
400
400
100
100
25
ns
ns
ns
ns
ns
ZH
C = 100pF
L
Figures 4, 5; S1 closed, R = 500Ω,
L
t
ZL
LZ
HZ
C = 100pF
L
Figures 4, 5; S1 closed, R = 500Ω,
L
t
C = 100pF
L
Figures 4, 5; S2 closed, R = 500Ω,
L
t
C = 100pF
L
Device-to-Device Propagation
Delay Matching
Same power supply, maximum temperature
difference between devices = +30°C (Note 5)
Note 1: Devices production tested at +25°C. Limits over the operating temperature range are guaranteed by design.
Note 2: All currents into the device are positive; all currents out of the device are negative. All voltages are referenced to device
ground, unless otherwise noted.
Note 3: ∆V
and ∆V
are the changes in V
and V , respectively, when the DI input changes state.
OD
OC
OD OC
Note 4: The maximum current applies to peak current just prior to foldback current limiting.
Note 5: Guaranteed by design; not production tested.
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MAX3293–MAX3295
20Mbps, +3.3V, SOT23 RS-485/
RS-422 Transmitters
Test Circuits and Timing Diagrams
Y
R
V
CC
S1
S2
R
L
OUTPUT
UNDER TEST
V
OD
R
C
V
L
OC
Z
Figure 1. Driver DC Test Load
Figure 4. Enable/Disable Timing Test Load
3V
DE
1.5V
1.5V
3V
0V
DE
t
t
, t
LZ
ZL(SHDN) ZL
C
C
L
L
Y
Y, Z
DI
R
DIFF
V
ID
V + 0.25V
OL
2.3V
OUTPUT NORMALLY LOW
OUTPUT NORMALLY HIGH
V
Z
OL
Y, Z
0V
2.3V
t
V
OH
- 0.25V
t
HZ
, t
ZH(SHDN) ZH
Figure 2. Driver Timing Test Circuit
Figure 5. Driver Enable and Disable Times
f = 1MHz, t 3ns, t 3ns
R
F
3V
0V
DI
1.5V
1.5V
t
t
PHL
PLH
1/2 V
O
Z
Y
V
O
1/2 V
O
V
= V (Y) - V (Z)
DIFF
V
0V
O
90%
90%
V
DIFF
10%
10%
-V
O
t
R
t
F
t
= | t
- t
|
SKEW
PLH PHL
Figure 3. Driver Propagation Delays
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MAX3293–MAX3295
20Mbps, +3.3V, SOT23 RS-485/
RS-422 Transmitters
Typical Operating Characteristics
(V
= +3.3V, T = +25°C, unless otherwise noted.)
A
CC
MAX3295
SHUTDOWN SUPPLY CURRENT
SUPPLY CURRENT vs. DATA RATE
vs. TEMPERATURE
SUPPLY CURRENT vs. TEMPERATURE
25
2.0
1.6
1.2
0.8
0.4
0
2.0
1.5
DE = V
NO LOAD
DE = GND
DE = V
CC
NO LOAD
NO SWITCHING
CC
T
= +85C
20
15
10
5
A
T
A
= +125C
1.0
0.5
0
T
= +25C
A
T
A
= -40C
0
0
5
10
DATA RATE (Mbps)
15
20
-40
-10
20
50
80
110
-40
-10
20
50
80
110
TEMPERATURE (C)
TEMPERATURE (C)
OUTPUT CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
DRIVER DIFFERENTIAL OUTPUT VOLTAGE
vs. TEMPERATURE
DRIVER-OUTPUT CURRENT
vs. DRIVER-OUTPUT LOW VOLTAGE
140
120
100
80
50
40
30
20
10
0
3.5
3.0
2.5
2.0
1.5
1.0
R
R
= 100Ω
= 54Ω
DIFF
DIFF
60
40
20
0
0
2
4
6
8
10
12
1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50
DIFFERENTIAL OUTPUT VOLTAGE (V)
-40
-10
20
50
80
110
OUTPUT LOW VOLTAGE (V)
TEMPERATURE (C)
DRIVER PROPAGATION DELAY
vs. TEMPERATURE
DRIVER-OUTPUT CURRENT
vs. DRIVER-OUTPUT HIGH VOLTAGE
OUTPUT SKEW vs. TEMPERATURE
40
30
4
20
R
= 54Ω
DIFF
C = 50pF
L
0
-20
-40
-60
-80
3
t
t
PHL
20
10
0
2
1
0
PLH
-100
-120
-7
-5
-3
-1
1
3
5
-40
-10
20
50
80
110
-40
-10
20
50
80
110
OUTPUT HIGH VOLTAGE (V)
TEMPERATURE (C)
TEMPERATURE (C)
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MAX3293–MAX3295
20Mbps, +3.3V, SOT23 RS-485/
RS-422 Transmitters
Typical Operating Characteristics (continued)
(V
= +3.3V, T = +25°C, unless otherwise noted.)
A
CC
UNLOADED DRIVER-OUTPUT
DRIVER PROPAGATION DELAY
WAVEFORM (f = 16Mbps)
ENABLE RESPONSE TIME
IN
MAX3293-95 toc10
MAX3293-95 toc11
MAX3293-95 toc12
DI
0V
DE
0V
Y-Z
0V
Y, Z
0V
Y, Z
0V
20ns/div
40ns/div
20ns/div
Y, Z: 1V/div
DI: 2V/div
Y, Z: 1V/div
Y, Z, DE: 2V/div
LOADED DRIVER-OUTPUT WAVEFORM
(f = 16Mbps)
IN
EYE DIAGRAM (f = 20Mbps)
IN
MAX3293-95 toc13
MAX3293-95 toc14
Y, Z
0V
Y, Z
0V
20ns/div
10ns/div
Y, Z: 500mV/div
Y, Z: 500mV/div
Pin Description
PIN
NAME
FUNCTION
Driver Input. A logic low on DI forces the noninverting output (Y) low and the inverting output (Z) high.
A logic high on DI forces the noninverting output (Y) high and the inverting output (Z) low.
1
DI
2
V
CC
Positive Supply. V
= +3.3V ±5%. Bypass V
to GND with a 0.1µF capacitor.
CC
CC
Driver Output Enable. Force DE high to enable driver. Pull DE low to disable the driver. Hot-swap
input, see the Hot-Swap Capability section.
3
DE
4
5
6
Z
GND
Y
Inverting RS-485/RS-422 Output
Ground
Noninverting RS-485/RS-422 Output
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MAX3293–MAX3295
20Mbps, +3.3V, SOT23 RS-485/
RS-422 Transmitters
cause coupling of V
improperly enable the driver.
or GND to DE. These factors could
CC
Detailed Description
The MAX3293/MAX3294/MAX3295 are low-power trans-
mitters for RS-485/RS-422 communication. The MAX3295
operates at data rates up to 20Mbps, the MAX3294 up
to 2.5Mbps (slew-rate limited), and the MAX3293 up to
250kbps (slew-rate limited). These devices are enabled
using an active-high driver enable (DE) input. When
disabled, outputs enter a high-impedance state, and the
supply current reduces to 1µA.
The MAX3293/MAX3294/MAX3295 eliminate all above
issues with hot-swap circuitry. When V
nal pulldown circuit holds DE low for approximately 10µs.
After the initial power-up sequence, the pulldown circuit
becomes transparent, resetting the hot-swap tolerable
input.
rises, an inter-
CC
The MAX3293/MAX3294/MAX3295 have a hot-swap input
structure that prevents disturbance on the differential signal
lines when a circuit board is plugged into a “hot” back-
plane (see the Hot-Swap Capability section). Drivers are
also short-circuit current limited and are protected against
excessive power dissipation by thermal-shutdown circuitry.
V
CC
10µs
TIMER
Driver
TIMER
The driver accepts a single-ended, logic-level input
(DI) and translates it to a differential RS-485/RS-422
level output (Y and Z). Driving DE high enables the
driver, while pulling DE low places the driver outputs
(Y and Z) into a high-impedance state (see Table 1).
Low-Power Shutdown
5.6kΩ
DE
EN
(HOT SWAP)
Force DE low to disable the MAX3293/MAX3294/
MAX3295. In shutdown mode, the device consumes a
maximum of 10µA of supply current.
2mA
100µA
M1
M2
Hot-Swap Capability
Hot-Swap Input
When circuit boards are inserted into a “hot” or pow-
ered backplane, disturbances to the enable can lead
to data errors. Upon initial circuit board insertion, the
processor undergoes its power-up sequence. During
this period, the output drivers are high impedance
and are unable to drive the DE input of the MAX3293/
MAX3294/MAX3295 to a defined logic level. Leakage
currents up to 10µA from the high-impedance out-
put could cause DE to drift to an incorrect logic state.
Additionally, parasitic circuit board capacitance could
Figure 6. Simplified Structure of the Driver Enable Input (DE)
DIFFERENTIAL POWER-UP GLITCH
(0.1V/µs)
2V/div
0V
V
CC
10mV/div
AC-COUPLED
Y
Z
Table 1. MAX3293/MAX3294/
MAX3295 (RS-485/RS-422) Transmitting
Function Table
10mV/div
AC-COUPLED
INPUTS
OUTPUTS
20mV/div
Y-Z
DE
0
DI
X
0
Y
Z
4µs/div
Shutdown
Shutdown
1
0
1
1
0
1
1
Figure 7. Differential Power-Up Glitch (0.1V/µs)
X = Don’t care.
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MAX3293–MAX3295
20Mbps, +3.3V, SOT23 RS-485/
RS-422 Transmitters
off. When M1 turns off, DE reverts to a standard,
Hot-Swap Input Circuitry
high-impedance CMOS input. Whenever V
below 1V, the hot-swap input is reset.
drops
CC
The MAX3293/MAX3294/MAX3295 enable input fea-
tures hot-swap capability. At the input, there are two
NMOS devices, M1 and M2 (Figure 6). When V
CC
Hot-Swap Line Transient
ramps from zero, an internal 10µs timer turns on
M2 and sets the SR latch, which also turns on M1.
Transistors M2, a 2mA current sink, and M1, a 100µA
current sink, pull DE to GND through a 5.6kΩ resistor.
M2 is designed to pull DE to the disabled state against
an external parasitic capacitance up to 100pF that may
drive DE high. After 10µs, the timer deactivates M2
while M1 remains on, holding DE low against three-
state leakages 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
During a hot-swap event when the driver is connected to
the line and is powered up, the driver must not cause the
differential signal to drop below 200mV. Figures 7, 8, and
9 show the results of the MAX3295 during power-up for
three different V
ramp rates (0.1V/µs, 1V/µs, and 10V/
CC
µs). The photos show the V
ramp, the single-ended
CC
signal on each side of the 100Ω termination, as well as
the differential signal across the termination.
ESD Protection
Human Body Model
Figure 10 shows the Human Body Model, and Figure 11
shows the current waveform it generates when discharged
into low impedance. This model consists of a 100pF capac-
itor charged to the ESD voltage of interest, which is then
discharged into the device through a 1.5kΩ resistor.
DIFFERENTIAL POWER-UP GLITCH
(1V/µs)
2V/div
0V
V
CC
100mV/div
AC-COUPLED
Y
Z
R
C
R
D
100mV/div
AC-COUPLED
1MΩ
1.5kΩ
DISCHARGE
RESISTANCE
CHARGE-CURRENT-
LIMIT RESISTOR
200mV/div
Y-Z
HIGH-
VOLTAGE
DC
DEVICE
UNDER
TEST
C
100pF
STORAGE
CAPACITOR
s
SOURCE
1µs/div
Figure 8. Differential Power-Up Glitch (1V/µs)
Figure 10. Human Body ESD Test
DIFFERENTIAL POWER-UP GLITCH
(10V/µs)
2V/div
0V
V
CC
I
r
I
100%
90%
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
P
AMPERES
50mV/div
Y
Z
AC-COUPLED
36.8%
50mV/div
AC-COUPLED
10%
0V
0V
TIME
Y-Z
t
RL
100mV/div
t
DL
CURRENT WAVEFORM
200ns/div
Figure 11. Current Waveform
Figure 9. Differential Power-Up Glitch (10V/µs)
Maxim Integrated
│ 9
www.maximintegrated.com
MAX3293–MAX3295
20Mbps, +3.3V, SOT23 RS-485/
RS-422 Transmitters
Reduced EMI and Reflections
Driver-Output Protection
(MAX3293/MAX3294)
Two mechanisms prevent excessive output current and
power dissipation caused by faults or by bus contention.
The first, a foldback current limit on the output stage,
provides immediate protection against short circuits over
the whole common-mode voltage range (see the Typical
Operating Characteristics). The second, a thermal-shut-
down circuit, forces the driver outputs into a high-imped-
ance state if the die temperature exceeds +160°C.
The MAX3293/MAX3294 are slew-rate limited, minimizing
EMI and reducing reflections caused by improperly ter-
minated cables. Figure 12 shows Fourier analysis of the
MAX3295 transmitting a 125kHz signal. High-frequency
harmonics with large amplitudes are evident. Figure 13
shows the same information, but for the slew-rate-limited
MAX3293, transmitting the same signal. The high-fre-
quency harmonics have much lower amplitudes, and the
potential for EMI is significantly reduced.
Chip Information
PROCESS: BiCMOS
To minimize reflections, the line should be terminated at
both ends in its characteristic impedance, and stub lengths
off the main line should be kept as short as possible. The
slew-rate-limited MAX3293 and MAX3294 are more toler-
ant of imperfect termination.
DRIVER-OUTPUT WAVEFORM AND
FFT PLOT OF MAX3295
DRIVER-OUTPUT WAVEFORM AND
FFT PLOT OF MAX3293
10dB/div
10dB/div
Figure 13. Driver-Output Waveform and FFT Plot of MAX3293
Transmitting a 125kHz Signal
Figure 12. Driver-Output Waveform and FFT Plot of MAX3295
Transmitting a 125kHz Signal
Pin Configuration
Package Information
For the latest package outline information and land patterns
(footprints), go to www.maximintegrated.com/packages. Note
that a “+”, “#”, or “-” in the package code indicates RoHS status
only. Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
TOP VIEW
+
DI
1
2
3
6
5
4
Y
MAX3293
MAX3294
MAX3295
V
CC
GND
Z
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERNNO.
DE
6 SOT23
U6CN+2
21-0058
90-0175
SOT23-6
Maxim Integrated
│ 10
www.maximintegrated.com
MAX3293–MAX3295
20Mbps, +3.3V, SOT23 RS-485/
RS-422 Transmitters
Revision History
REVISION REVISION
PAGES
CHANGED
DESCRIPTION
NUMBER
DATE
3
4
3/11
Added lead-free parts to the Ordering Information and Selector Guide tables
Added MAX3295AUT/V+T to Ordering Information
1
1
12/14
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
©
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
2014 Maxim Integrated Products, Inc.
│ 11
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